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Gao X, Bian T, Gao P, Ge X, Zhang Y, Han J, Guo X, Zhou L, Yang H. Fidelity Characterization of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus and NADC30-like Strain. Viruses 2024; 16:797. [PMID: 38793678 PMCID: PMC11125636 DOI: 10.3390/v16050797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
The porcine reproductive and respiratory syndrome virus (PRRSV) has significantly impacted the global pork industry for over three decades. Its high mutation rates and frequent recombination greatly intensifies its epidemic and threat. To explore the fidelity characterization of Chinese highly pathogenic PRRSV JXwn06 and the NADC30-like strain CHsx1401, self-recombination and mutation in PAMs, MARC-145 cells, and pigs were assessed. In vitro, CHsx1401 displayed a higher frequency of recombination junctions and a greater diversity of junction types than JXwn06. In vivo, CHsx1401 exhibited fewer junction types yet maintained a higher junction frequency. Notably, JXwn06 showed more accumulation of mutations. To pinpoint the genomic regions influencing their fidelity, chimeric viruses were constructed, with the exchanged nsp9-10 regions between JXwn06 and CHsx1401. The SJn9n10 strain, which incorporates JXwn06's nsp9-10 into the CHsx1401 genome, demonstrated reduced sensitivity to nucleotide analogs compared to CHsx1401. Conversely, compared with JXwn06, the JSn9n10 strain showed increased sensitivity to these inhibitors. The swapped nsp9-10 also influences the junction frequency and accumulated mutations as their donor strains. The results indicate a propensity for different types of genetic variations between these two strains and further highlight the nsp9-10 region as a critical determinant of their fidelity.
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Affiliation(s)
- Xiang Gao
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Ting Bian
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Peng Gao
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Xinna Ge
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Yongning Zhang
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Jun Han
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Xin Guo
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Lei Zhou
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
| | - Hanchun Yang
- National Key Laboratory of Veterinary Public Health Safety, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China; (X.G.)
- Key Laboratory of Animal Epidemiology of Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing 100094, China
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Wang M, Wang L, Leng P, Guo J, Zhou H. Drugs targeting structural and nonstructural proteins of the chikungunya virus: A review. Int J Biol Macromol 2024; 262:129949. [PMID: 38311132 DOI: 10.1016/j.ijbiomac.2024.129949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 01/26/2024] [Accepted: 02/01/2024] [Indexed: 02/06/2024]
Abstract
Chikungunya virus (CHIKV) is a single positive-stranded RNA virus of the Togaviridae family and Alphavirus genus, with a typical lipid bilayer envelope structure, and is the causative agent of human chikungunya fever (CHIKF). The U.S. Food and Drug Administration has recently approved the first chikungunya vaccine, Ixchiq; however, vaccination rates are low, and CHIKF is prevalent owing to its periodic outbreaks. Thus, developing effective anti-CHIKV drugs in clinical settings is imperative. Viral proteins encoded by the CHIKV genome play vital roles in all stages of infection, and developing therapeutic agents that target these CHIKV proteins is an effective strategy to improve CHIKF treatment efficacy and reduce mortality rates. Therefore, in the present review article, we aimed to investigate the basic structure, function, and replication cycle of CHIKV and comprehensively outline the current status and future advancements in anti-CHIKV drug development, specifically targeting nonstructural (ns) proteins, including nsP1, nsP2, nsP3, and nsP4 and structural proteins such as capsid (C), E3, E2, 6K, and E1.
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Affiliation(s)
- Mengke Wang
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Lidong Wang
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Ping Leng
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Jinlin Guo
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Hao Zhou
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China; Chongqing Key Laboratory of Sichuan-Chongqing Co-construction for Diagnosis and Treatment of Infectious Diseases Integrated Traditional Chinese and Western Medicine, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400016, China.
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Hodoameda P, Ebel GD, Mukhopadhyay S, Clem RJ. Extreme infectious titer variability in individual Aedes aegypti mosquitoes infected with Sindbis virus is associated with both differences in virus population structure and dramatic disparities in specific infectivity. PLoS Pathog 2024; 20:e1012047. [PMID: 38412195 PMCID: PMC10923411 DOI: 10.1371/journal.ppat.1012047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 03/08/2024] [Accepted: 02/13/2024] [Indexed: 02/29/2024] Open
Abstract
Variability in how individuals respond to pathogens is a hallmark of infectious disease, yet the basis for individual variation in host response is often poorly understood. The titer of infectious virus among individual mosquitoes infected with arboviruses is frequently observed to vary by several orders of magnitude in a single experiment, even when the mosquitoes are highly inbred. To better understand the basis for this titer variation, we sequenced populations of Sindbis virus (SINV) obtained from individual infected Aedes aegypti mosquitoes that, despite being from a highly inbred laboratory colony, differed in their titers of infectious virus by approximately 10,000-fold. We observed genetic differences between these virus populations that indicated the virus present in the midguts of low titer mosquitoes was less fit than that of high titer mosquitoes, possibly due to founder effects that occurred during midgut infection. Furthermore, we found dramatic differences in the specific infectivity or SI (the ratio of infectious units/viral genome equivalents) between these virus populations, with the SI of low titer mosquitoes being up to 10,000-fold lower than that of high titer mosquitoes. Despite having similar amounts of viral genomes, low titer mosquitoes appeared to contain less viral particles, suggesting that viral genomes were packaged into virions less efficiently than in high titer mosquitoes. Finally, antibiotic treatment, which has been shown to suppress mosquito antiviral immunity, caused an increase in SI. Our results indicate that the extreme variation that is observed in SINV infectious titer between individual Ae. aegypti mosquitoes is due to both genetic differences between virus populations and to differences in the proportion of genomes that are packaged into infectious particles.
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Affiliation(s)
- Peter Hodoameda
- Division of Biology, Kansas State University, Manhattan, Kansas United States of America
| | - Gregory D. Ebel
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado United States of America
| | - Suchetana Mukhopadhyay
- Department of Biology, Indiana University, Bloomington, Indiana United States of America
| | - Rollie J. Clem
- Division of Biology, Kansas State University, Manhattan, Kansas United States of America
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Martin MF, Bonaventure B, McCray NE, Peersen OB, Rozen-Gagnon K, Stapleford KA. Distinct chikungunya virus polymerase palm subdomains contribute to virus replication and virion assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.15.575630. [PMID: 38293111 PMCID: PMC10827052 DOI: 10.1101/2024.01.15.575630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Alphaviruses encode an error-prone RNA-dependent RNA polymerase (RdRp), nsP4, required for genome synthesis, yet how the RdRp functions in the complete alphavirus life cycle is not well-defined. Previous work using chikungunya virus (CHIKV) has established the importance of the nsP4 residue cysteine 483 in maintaining viral genetic fidelity. Given the location of residue C483 in the nsP4 palm domain, we hypothesized that other residues within this domain and surrounding subdomains would also contribute to polymerase function. To test this hypothesis, we designed a panel of nsP4 variants via homology modeling based on the Coxsackievirus B3 3 polymerase. We rescued each variant in both mammalian and mosquito cells and discovered that the palm domain and ring finger subdomain contribute to polymerase host-specific replication and genetic stability. Surprisingly, in mosquito cells, these variants in the ring finger and palm domain were replication competent and produced viral structural proteins, but they were unable to produce infectious progeny, indicating a yet uncharacterized role for the polymerase in viral assembly. Finally, we have identified additional residues in the nsP4 palm domain that influence the genetic diversity of the viral progeny, potentially via an alteration in NTP binding and/or discrimination by the polymerase. Taken together, these studies highlight that distinct nsP4 subdomains regulate multiple processes of the alphavirus life cycle, placing nsP4 in a central role during the switch from RNA synthesis to packaging and assembly.
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Affiliation(s)
- Marie-France Martin
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Boris Bonaventure
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Nia E. McCray
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Olve B. Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | | | - Kenneth A. Stapleford
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
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Avadhanula V, Agustinho DP, Menon VK, Chemaly RF, Shah DP, Qin X, Surathu A, Doddapaneni H, Muzny DM, Metcalf GA, Cregeen SJ, Gibbs RA, Petrosino JF, Sedlazeck FJ, Piedra PA. Inter and intra-host diversity of RSV in hematopoietic stem cell transplant adults with normal and delayed viral clearance. Virus Evol 2023; 10:vead086. [PMID: 38361816 PMCID: PMC10868550 DOI: 10.1093/ve/vead086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 12/05/2023] [Accepted: 12/22/2023] [Indexed: 02/17/2024] Open
Abstract
Respiratory syncytial virus (RSV) infection in immunocompromised individuals often leads to prolonged illness, progression to severe lower respiratory tract infection, and even death. How the host immune environment of the hematopoietic stem cell transplant (HCT) adults can affect viral genetic variation during an acute infection is not understood well. In the present study, we performed whole genome sequencing of RSV/A or RSV/B from samples collected longitudinally from HCT adults with normal (<14 days) and delayed (≥14 days) RSV clearance who were enrolled in a ribavirin trial. We determined the inter-host and intra-host genetic variation of RSV and the effect of mutations on putative glycosylation sites. The inter-host variation of RSV is centered in the attachment (G) and fusion (F) glycoprotein genes followed by polymerase (L) and matrix (M) genes. Interestingly, the overall genetic variation was constant between normal and delayed clearance groups for both RSV/A and RSV/B. Intra-host variation primarily occurred in the G gene followed by non-structural protein (NS1) and L genes; however, gain or loss of stop codons and frameshift mutations appeared only in the G gene and only in the delayed viral clearance group. Potential gain or loss of O-linked glycosylation sites in the G gene occurred both in RSV/A and RSV/B isolates. For RSV F gene, loss of N-linked glycosylation site occurred in three RSV/B isolates within an antigenic epitope. Both oral and aerosolized ribavirin did not cause any mutations in the L gene. In summary, prolonged viral shedding and immune deficiency resulted in RSV variation, especially in structural mutations in the G gene, possibly associated with immune evasion. Therefore, sequencing and monitoring of RSV isolates from immunocompromised patients are crucial as they can create escape mutants that can impact the effectiveness of upcoming vaccines and treatments.
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Affiliation(s)
| | | | - Vipin Kumar Menon
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Roy F Chemaly
- Departments of Infectious Diseases, Infection Control & Employee Health, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Dimpy P Shah
- Department of Population Health Sciences, Mays Cancer Center, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Xiang Qin
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Anil Surathu
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030,USA
| | - Harshavardhan Doddapaneni
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Donna M Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ginger A Metcalf
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sara Javornik Cregeen
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030,USA
| | - Richard A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Joseph F Petrosino
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030,USA
| | - Fritz J Sedlazeck
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Computer Science, Rice University, Houston, TX 77030, USA
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030,USA
| | - Pedro A Piedra
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030,USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
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6
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Perkovic M, Gawletta S, Hempel T, Brill S, Nett E, Sahin U, Beissert T. A trans-amplifying RNA simplified to essential elements is highly replicative and robustly immunogenic in mice. Mol Ther 2023; 31:1636-1646. [PMID: 36694464 PMCID: PMC10277886 DOI: 10.1016/j.ymthe.2023.01.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 12/14/2022] [Accepted: 01/19/2023] [Indexed: 01/25/2023] Open
Abstract
Trans-amplifying RNA (taRNA) is a split-vector derivative of self-amplifying RNA (saRNA) and a promising vaccine platform. taRNA combines a non-replicating mRNA encoding an alphaviral replicase and a transreplicon (TR) RNA coding for the antigen. Upon translation, the replicase amplifies the antigen-coding TR, thereby requiring minimal amounts of TR for immunization. TR amplification by the replicase follows a complex mechanism orchestrated by genomic and subgenomic promoters (SGPs) and generates genomic and subgenomic amplicons whereby only the latter are translated into therapeutic proteins. This complexity merits simplification to improve the platform. Here, we eliminated the SGP and redesigned the 5' untranslated region to shorten the TR (STR), thereby enabling translation of the remaining genomic amplicon. We then applied a directed evolution approach to select for faster replicating STRs. The resulting evolved STR (eSTR) had acquired A-rich 5' extensions, which improved taRNA expression thanks to accelerated replication. Consequently, we reduced the minimal required TR amount by more than 10-fold without losing taRNA expression in vitro. Accordingly, eSTR-immunized mice developed greater antibody titers to taRNA-encoded influenza HA than TR-immunized mice. In summary, this work points the way for further optimization of taRNA by combining rational design and directed evolution.
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Affiliation(s)
- Mario Perkovic
- TRON - Translational Oncology, Johannes Gutenberg University, Freiligrathstrasse 12, 55131 Mainz, Germany
| | - Stefanie Gawletta
- TRON - Translational Oncology, Johannes Gutenberg University, Freiligrathstrasse 12, 55131 Mainz, Germany
| | - Tina Hempel
- TRON - Translational Oncology, Johannes Gutenberg University, Freiligrathstrasse 12, 55131 Mainz, Germany
| | - Silke Brill
- TRON - Translational Oncology, Johannes Gutenberg University, Freiligrathstrasse 12, 55131 Mainz, Germany
| | - Evelin Nett
- TRON - Translational Oncology, Johannes Gutenberg University, Freiligrathstrasse 12, 55131 Mainz, Germany
| | - Ugur Sahin
- TRON - Translational Oncology, Johannes Gutenberg University, Freiligrathstrasse 12, 55131 Mainz, Germany; BioNTech SE, An der Goldgrube 12, 55131 Mainz, Germany.
| | - Tim Beissert
- TRON - Translational Oncology, Johannes Gutenberg University, Freiligrathstrasse 12, 55131 Mainz, Germany.
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Xiong D, Zhang X, Yu J, Wei H. Distribution of intra‐host variations and mutations in the genomes of SARS‐CoV‐2 and their implications on detection and therapeutics. MedComm (Beijing) 2022; 3:e186. [DOI: 10.1002/mco2.186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 10/25/2022] [Accepted: 10/27/2022] [Indexed: 12/03/2022] Open
Affiliation(s)
- Dongyan Xiong
- CAS Key Laboratory of Special Pathogens and Biosafety Center for Biosafety Mega‐Science Wuhan Institute of Virology Chinese Academy of Sciences Wuhan China
- CAS Key Laboratory of Special Pathogens and Biosafety University of Chinese Academy of Sciences Beijing China
| | - Xiaoxu Zhang
- CAS Key Laboratory of Special Pathogens and Biosafety Center for Biosafety Mega‐Science Wuhan Institute of Virology Chinese Academy of Sciences Wuhan China
| | - Junping Yu
- CAS Key Laboratory of Special Pathogens and Biosafety Center for Biosafety Mega‐Science Wuhan Institute of Virology Chinese Academy of Sciences Wuhan China
- CAS Key Laboratory of Special Pathogens and Biosafety University of Chinese Academy of Sciences Beijing China
| | - Hongping Wei
- CAS Key Laboratory of Special Pathogens and Biosafety Center for Biosafety Mega‐Science Wuhan Institute of Virology Chinese Academy of Sciences Wuhan China
- CAS Key Laboratory of Special Pathogens and Biosafety University of Chinese Academy of Sciences Beijing China
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Campagnola G, Govindarajan V, Pelletier A, Canard B, Peersen OB. The SARS-CoV nsp12 Polymerase Active Site Is Tuned for Large-Genome Replication. J Virol 2022; 96:e0067122. [PMID: 35924919 PMCID: PMC9400494 DOI: 10.1128/jvi.00671-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/06/2022] [Indexed: 01/18/2023] Open
Abstract
Positive-strand RNA viruses replicate their genomes using virally encoded RNA-dependent RNA polymerases (RdRP) with a common active-site structure and closure mechanism upon which replication speed and fidelity can evolve to optimize virus fitness. Coronaviruses (CoV) form large multicomponent RNA replication-transcription complexes containing a core RNA synthesis machine made of the nsp12 RdRP protein with one nsp7 and two nsp8 proteins as essential subunits required for activity. We show that assembly of this complex can be accelerated 5-fold by preincubation of nsp12 with nsp8 and further optimized with the use of a novel nsp8L7 heterodimer fusion protein construct. Using rapid kinetics methods, we measure elongation rates of up to 260 nucleotides (nt)/s for the core replicase, a rate that is unusually fast for a viral polymerase. To address the origin of this fast rate, we examined the roles of two CoV-specific residues in the RdRP active site: Ala547, which replaces a conserved glutamate above the bound NTP, and Ser759, which mutates the palm domain GDD sequence to SDD. Our data show that Ala547 allows for a doubling of replication rate, but this comes at a fidelity cost that is mitigated by using a SDD sequence in the palm domain. Our biochemical data suggest that fixation of mutations in polymerase motifs F and C played a key role in nidovirus evolution by tuning replication rate and fidelity to accommodate their large genomes. IMPORTANCE Replicating large genomes represents a challenge for RNA viruses because fast RNA synthesis is needed to escape innate immunity defenses, but faster polymerases are inherently low-fidelity enzymes. Nonetheless, the coronaviruses replicate their ≈30-kb genomes using the core polymerase structure and mechanism common to all positive-strand RNA viruses. The classic explanation for their success is that the large-genome nidoviruses have acquired an exonuclease-based repair system that compensates for the high polymerase mutation rate. In this work, we establish that the nidoviral polymerases themselves also play a key role in maintaining genome integrity via mutations at two key active-site residues that enable very fast replication rates while maintaining typical mutation rates. Our findings further demonstrate the evolutionary plasticity of the core polymerase platform by showing how it has adapted during the expansion from short-genome picornaviruses to long-genome nidoviruses.
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Affiliation(s)
- Grace Campagnola
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Vishnu Govindarajan
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Annelise Pelletier
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Bruno Canard
- Centre National de la Recherche Scientifique, Aix-Marseille Université CNRS UMR 7257, AFMB, Marseille, France
| | - Olve B. Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, Colorado, USA
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9
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Bifani AM, Siriphanitchakorn T, Choy MM. Intra-Host Diversity of Dengue Virus in Mosquito Vectors. Front Cell Infect Microbiol 2022; 12:888804. [PMID: 35811685 PMCID: PMC9256930 DOI: 10.3389/fcimb.2022.888804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/03/2022] [Indexed: 11/13/2022] Open
Abstract
Dengue virus (DENV) is the most common arbovirus, causing a significant burden on both the economy and global healthcare systems. The virus is transmitted by Aedes species of mosquitoes as a swarm of closely related virus genomes, collectively referred to as a quasispecies. The level of genomic diversity within this quasispecies varies as DENV moves through various ecological niches within its transmission cycle. Here, the factors that influence the level of DENV quasispecies diversity during the course of infection in the mosquito vectors are reviewed.
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10
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LoMascolo NJ, Cruz-Pulido YE, Mounce BC. Bisacodyl Limits Chikungunya Virus Replication In Vitro and Is Broadly Antiviral. Antimicrob Agents Chemother 2022; 66:e0029222. [PMID: 35652314 PMCID: PMC9211418 DOI: 10.1128/aac.00292-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/10/2022] [Indexed: 11/20/2022] Open
Abstract
Identifying novel antivirals requires significant time and resource investment, and the continuous threat of viruses to human health necessitates commitment to antiviral identification and development. Developing antivirals requires years of research and validation, and recent outbreaks have highlighted the need for preparedness in counteracting pandemics. One way to facilitate development is to repurpose molecules already used clinically. By screening such compounds, we can accelerate antiviral development. Here, we screened compounds from the National Institutes of Health's Developmental Therapeutic Program for activity against chikungunya virus, an alphavirus that is responsible for a significant outbreak in the Americas in 2013. Using this library, we identified several compounds with known antiviral activity, as well as several novel antivirals. Given its favorable in vitro activity and well-described in vivo activity, as well as its broad availability, we focused on bisacodyl, a laxative used for the treatment of constipation, for follow-up studies. We find that bisacodyl inhibits chikungunya virus infection in a variety of cell types, over a range of concentrations, and over several rounds of replication. We find that bisacodyl does not disrupt chikungunya virus particles or interfere with their ability to attach to cells, but, instead, bisacodyl inhibits virus replication. Finally, we find that bisacodyl is broadly antiviral against a variety of RNA viruses, including enteroviruses, flaviviruses, bunyaviruses, and alphaviruses; however, it exhibited no activity against the DNA virus vaccinia virus. Together, these data highlight the power of compound screening to identify novel antivirals and suggest that bisacodyl may hold promise as a broad-spectrum antiviral.
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Affiliation(s)
- Natalie J. LoMascolo
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
- Infectious Diseases and Immunology Research Institute, Maywood, Illinois, USA
| | - Yazmin E. Cruz-Pulido
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
| | - Bryan C. Mounce
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois, USA
- Infectious Diseases and Immunology Research Institute, Maywood, Illinois, USA
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11
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Caldwell HS, Pata JD, Ciota AT. The Role of the Flavivirus Replicase in Viral Diversity and Adaptation. Viruses 2022; 14:1076. [PMID: 35632818 PMCID: PMC9143365 DOI: 10.3390/v14051076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 02/04/2023] Open
Abstract
Flaviviruses include several emerging and re-emerging arboviruses which cause millions of infections each year. Although relatively well-studied, much remains unknown regarding the mechanisms and means by which these viruses readily alternate and adapt to different hosts and environments. Here, we review a subset of the different aspects of flaviviral biology which impact host switching and viral fitness. These include the mechanism of replication and structural biology of the NS3 and NS5 proteins, which reproduce the viral genome; rates of mutation resulting from this replication and the role of mutational frequency in viral fitness; and the theory of quasispecies evolution and how it contributes to our understanding of genetic and phenotypic plasticity.
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Affiliation(s)
- Haley S. Caldwell
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA;
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
| | - Janice D. Pata
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
- Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Alexander T. Ciota
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA;
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
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12
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Hung SJ, Tsai HP, Wang YF, Ko WC, Wang JR, Huang SW. Assessment of the Risk of Severe Dengue Using Intrahost Viral Population in Dengue Virus Serotype 2 Patients via Machine Learning. Front Cell Infect Microbiol 2022; 12:831281. [PMID: 35223554 PMCID: PMC8866709 DOI: 10.3389/fcimb.2022.831281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 01/10/2022] [Indexed: 11/13/2022] Open
Abstract
Dengue virus, a positive-sense single-stranded RNA virus, continuously threatens human health. Although several criteria for evaluation of severe dengue have been recently established, the ability to prognose the risk of severe outcomes for dengue patients remains limited. Mutant spectra of RNA viruses, including single nucleotide variants (SNVs) and defective virus genomes (DVGs), contribute to viral virulence and growth. Here, we determine the potency of intrahost viral population in dengue patients with primary infection that progresses into severe dengue. A total of 65 dengue virus serotype 2 infected patients in primary infection including 17 severe cases were enrolled. We utilized deep sequencing to directly define the frequency of SNVs and detection times of DVGs in sera of dengue patients and analyzed their associations with severe dengue. Among the detected SNVs and DVGs, the frequencies of 9 SNVs and the detection time of 1 DVG exhibited statistically significant differences between patients with dengue fever and those with severe dengue. By utilizing the detected frequencies/times of the selected SNVs/DVG as features, the machine learning model showed high average with a value of area under the receiver operating characteristic curve (AUROC, 0.966 ± 0.064). The elevation of the frequency of SNVs at E (nucleotide position 995 and 2216), NS2A (nucleotide position 4105), NS3 (nucleotide position 4536, 4606), and NS5 protein (nucleotide position 7643 and 10067) and the detection times of the selected DVG that had a deletion junction in the E protein region (nucleotide positions of the junction: between 969 and 1022) increased the possibility of dengue patients for severe dengue. In summary, we demonstrated the detected frequencies/times of SNVs/DVG in dengue patients associated with severe disease and successfully utilized them to discriminate severe patients using machine learning algorithm. The identified SNVs and DVGs that are associated with severe dengue will expand our understanding of intrahost viral population in dengue pathogenesis.
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Affiliation(s)
- Su-Jhen Hung
- National Mosquito-Borne Diseases Control Research Center, National Health Research Institutes, Tainan, Taiwan
| | - Huey-Pin Tsai
- Department of Pathology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ya-Fang Wang
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
| | - Wen-Chien Ko
- Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jen-Ren Wang
- Department of Pathology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Tainan, Taiwan
- Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
| | - Sheng-Wen Huang
- National Mosquito-Borne Diseases Control Research Center, National Health Research Institutes, Tainan, Taiwan
- *Correspondence: Sheng-Wen Huang,
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13
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Jurković M, Slović A, Forčić D, Ivančić-Jelečki J, Košutić-Gulija T, Jagušić M. Influence of Ribavirin on Mumps Virus Population Diversity. Viruses 2021; 13:2535. [PMID: 34960805 PMCID: PMC8706638 DOI: 10.3390/v13122535] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/07/2021] [Accepted: 12/12/2021] [Indexed: 12/26/2022] Open
Abstract
Frequent mumps outbreaks in vaccinated populations and the occurrence of neurological complications (e.g., aseptic meningitis or encephalitis) in patients with mumps indicate the need for the development of more efficient vaccines as well as specific antiviral therapies. RNA viruses are genetically highly heterogeneous populations that exist on the edge of an error threshold, such that additional increases in mutational burden can lead to extinction of the virus population. Deliberate modulation of their natural mutation rate is being exploited as an antiviral strategy and a possibility for rational vaccine design. The aim of this study was to examine the ability of ribavirin, a broad-spectrum antiviral agent, to introduce mutations in the mumps virus (MuV) genome and to investigate if resistance develops during long-term in vitro exposure to ribavirin. An increase in MuV population heterogeneity in the presence of ribavirin has been observed after one passage in cell culture, as well as a bias toward C-to-U and G-to-A transitions, which have previously been defined as ribavirin-related. At higher ribavirin concentration, MuV loses its infectivity during serial passaging and does not recover. At low ribavirin concentration, serial passaging leads to a more significant increase in population diversity and a stronger bias towards ribavirin-related transitions, independently of viral strain or cell culture. In these conditions, the virus retains its initial growth capacity, without development of resistance at a whole-virus population level.
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Affiliation(s)
| | | | | | | | | | - Maja Jagušić
- Centre for Research and Knowledge Transfer in Biotechnology, University of Zagreb, Rockefellerova 10, 10000 Zagreb, Croatia; (M.J.); (A.S.); (D.F.); (J.I.-J.); (T.K.-G.)
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14
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Enhancing the Antiviral Potency of Nucleobases for Potential Broad-Spectrum Antiviral Therapies. Viruses 2021; 13:v13122508. [PMID: 34960780 PMCID: PMC8705664 DOI: 10.3390/v13122508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/29/2021] [Accepted: 12/08/2021] [Indexed: 11/16/2022] Open
Abstract
Broad-spectrum antiviral therapies hold promise as a first-line defense against emerging viruses by blunting illness severity and spread until vaccines and virus-specific antivirals are developed. The nucleobase favipiravir, often discussed as a broad-spectrum inhibitor, was not effective in recent clinical trials involving patients infected with Ebola virus or SARS-CoV-2. A drawback of favipiravir use is its rapid clearance before conversion to its active nucleoside-5′-triphosphate form. In this work, we report a synergistic reduction of flavivirus (dengue, Zika), orthomyxovirus (influenza A), and coronavirus (HCoV-OC43 and SARS-CoV-2) replication when the nucleobases favipiravir or T-1105 were combined with the antimetabolite 6-methylmercaptopurine riboside (6MMPr). The 6MMPr/T-1105 combination increased the C-U and G-A mutation frequency compared to treatment with T-1105 or 6MMPr alone. A further analysis revealed that the 6MMPr/T-1105 co-treatment reduced cellular purine nucleotide triphosphate synthesis and increased conversion of the antiviral nucleobase to its nucleoside-5′-monophosphate, -diphosphate, and -triphosphate forms. The 6MMPr co-treatment specifically increased production of the active antiviral form of the nucleobases (but not corresponding nucleosides) while also reducing levels of competing cellular NTPs to produce the synergistic effect. This in-depth work establishes a foundation for development of small molecules as possible co-treatments with nucleobases like favipiravir in response to emerging RNA virus infections.
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15
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Domingo E, García-Crespo C, Lobo-Vega R, Perales C. Mutation Rates, Mutation Frequencies, and Proofreading-Repair Activities in RNA Virus Genetics. Viruses 2021; 13:1882. [PMID: 34578463 PMCID: PMC8473064 DOI: 10.3390/v13091882] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/06/2021] [Accepted: 09/17/2021] [Indexed: 12/29/2022] Open
Abstract
The error rate displayed during template copying to produce viral RNA progeny is a biologically relevant parameter of the replication complexes of viruses. It has consequences for virus-host interactions, and it represents the first step in the diversification of viruses in nature. Measurements during infections and with purified viral polymerases indicate that mutation rates for RNA viruses are in the range of 10-3 to 10-6 copying errors per nucleotide incorporated into the nascent RNA product. Although viruses are thought to exploit high error rates for adaptation to changing environments, some of them possess misincorporation correcting activities. One of them is a proofreading-repair 3' to 5' exonuclease present in coronaviruses that may decrease the error rate during replication. Here we review experimental evidence and models of information maintenance that explain why elevated mutation rates have been preserved during the evolution of RNA (and some DNA) viruses. The models also offer an interpretation of why error correction mechanisms have evolved to maintain the stability of genetic information carried out by large viral RNA genomes such as the coronaviruses.
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Affiliation(s)
- Esteban Domingo
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain;
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Carlos García-Crespo
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain;
| | - Rebeca Lobo-Vega
- Department of Clinical Microbiology, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Av. Reyes Católicos 2, 28040 Madrid, Spain;
| | - Celia Perales
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, 28049 Madrid, Spain;
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Department of Clinical Microbiology, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Av. Reyes Católicos 2, 28040 Madrid, Spain;
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16
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Trompet E, Temblador A, Gillemot S, Topalis D, Snoeck R, Andrei G. An MHV-68 Mutator Phenotype Mutant Virus, Confirmed by CRISPR/Cas9-Mediated Gene Editing of the Viral DNA Polymerase Gene, Shows Reduced Viral Fitness. Viruses 2021; 13:v13060985. [PMID: 34073189 PMCID: PMC8227558 DOI: 10.3390/v13060985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/11/2021] [Accepted: 05/24/2021] [Indexed: 12/04/2022] Open
Abstract
Drug resistance studies on human γ-herpesviruses are hampered by the absence of an in vitro system that allows efficient lytic viral replication. Therefore, we employed murine γ-herpesvirus-68 (MHV-68) that efficiently replicates in vitro as a model to study the antiviral resistance of γ-herpesviruses. In this study, we investigated the mechanism of resistance to nucleoside (ganciclovir (GCV)), nucleotide (cidofovir (CDV), HPMP-5azaC, HPMPO-DAPy) and pyrophosphate (foscarnet (PFA)) analogues and the impact of these drug resistance mutations on viral fitness. Viral fitness was determined by dual infection competition assays, where MHV-68 drug-resistant viral clones competed with the wild-type virus in the absence and presence of antivirals. Using next-generation sequencing, the composition of the viral populations was determined at the time of infection and after 5 days of growth. Antiviral drug resistance selection resulted in clones harboring mutations in the viral DNA polymerase (DP), denoted Y383SGCV, Q827RHPMP-5azaC, G302WPFA, K442TPFA, G302W+K442TPFA, C297WHPMPO-DAPy and C981YCDV. Without antiviral pressure, viral clones Q827RHPMP-5azaC, G302WPFA, K442TPFA and G302W+K442TPFA grew equal to the wild-type virus. However, in the presence of antivirals, these mutants had a growth advantage over the wild-type virus that was moderately to very strongly correlated with antiviral resistance. The Y383SGCV mutant was more fit than the wild-type virus with and without antivirals, except in the presence of brivudin. The C297W and C981Y changes were associated with a mutator phenotype and had a severely impaired viral fitness in the absence and presence of antivirals. The mutator phenotype caused by C297W in MHV-68 DP was validated by using a CRISPR/Cas9 genome editing approach.
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17
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Development of a Genetically Stable Live Attenuated Influenza Vaccine Strain Using an Engineered High-Fidelity Viral Polymerase. J Virol 2021; 95:JVI.00493-21. [PMID: 33827947 DOI: 10.1128/jvi.00493-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 12/28/2022] Open
Abstract
RNA viruses demonstrate a vast range of variants, called quasispecies, due to error-prone replication by viral RNA-dependent RNA polymerase. Although live attenuated vaccines are effective in preventing RNA virus infection, there is a risk of reversal to virulence after their administration. To test the hypothesis that high-fidelity viral polymerase reduces the diversity of influenza virus quasispecies, resulting in inhibition of reversal of the attenuated phenotype, we first screened for a high-fidelity viral polymerase using serial virus passages under selection with a guanosine analog ribavirin. Consequently, we identified a Leu66-to-Val single amino acid mutation in polymerase basic protein 1 (PB1). The high-fidelity phenotype of PB1-L66V was confirmed using next-generation sequencing analysis and biochemical assays with the purified influenza viral polymerase. As expected, PB1-L66V showed at least two-times-lower mutation rates and decreased misincorporation rates, compared to the wild type (WT). Therefore, we next generated an attenuated PB1-L66V virus with a temperature-sensitive (ts) phenotype based on FluMist, a live attenuated influenza vaccine (LAIV) that can restrict virus propagation by ts mutations, and examined the genetic stability of the attenuated PB1-L66V virus using serial virus passages. The PB1-L66V mutation prevented reversion of the ts phenotype to the WT phenotype, suggesting that the high-fidelity viral polymerase could contribute to generating an LAIV with high genetic stability, which would not revert to the pathogenic virus.IMPORTANCE The LAIV currently in use is prescribed for actively immunizing individuals aged 2 to 49 years. However, it is not approved for infants and elderly individuals, who actually need it the most, because it might prolong virus propagation and cause an apparent infection in these individuals, due to their weak immune systems. Recently, reversion of the ts phenotype of the LAIV strain currently in use to a pathogenic virus was demonstrated in cultured cells. Thus, the generation of mutations associated with enhanced virulence in LAIV should be considered. In this study, we isolated a novel influenza virus strain with a Leu66-to-Val single amino acid mutation in PB1 that displayed a significantly higher fidelity than the WT. We generated a novel LAIV candidate strain harboring this mutation. This strain showed higher genetic stability and no ts phenotype reversion. Thus, our high-fidelity strain might be useful for the development of a safer LAIV.
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18
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Attenuated dengue viruses are genetically more diverse than their respective wild-type parents. NPJ Vaccines 2021; 6:76. [PMID: 34017007 PMCID: PMC8138019 DOI: 10.1038/s41541-021-00340-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 03/31/2021] [Indexed: 11/09/2022] Open
Abstract
Dengue poses a significant burden of individual health, health systems and the economy in dengue endemic regions. As such, dengue vaccine development has been an active area of research. Previous studies selected attenuated vaccine candidates based on plaque size. However, these candidates led to mixed safety outcome in clinical trials, suggesting it is insufficiently informative as an indicator of dengue virus (DENV) attenuation. In this study, we examined the genome diversity of wild-type DENVs and their attenuated derivatives developed by Mahidol University and tested in phase 1 clinical trials. We found that the attenuated DENVs, in particular the strain under clinical development by Takeda Vaccines, DENV2 PDK53, showed significantly higher genome diversity than its wild-type parent, DENV2 16681. The determinant of genomic diversity was intrinsic to the PDK53 genome as infectious clone of PDK53 showed greater genomic diversity after a single in vitro passage compared to 16681 infectious clone. Similar trends were observed with attenuated DENV1 and DENV4, both of which were shown to be attenuated clinically, but not DENV3 that was not adequately attenuated clinically. Taken together, evidence presented here suggests that genome diversity could be developed into a marker of DENV attenuation.
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19
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Hucke FIL, Bugert JJ. Current and Promising Antivirals Against Chikungunya Virus. Front Public Health 2020; 8:618624. [PMID: 33384981 PMCID: PMC7769948 DOI: 10.3389/fpubh.2020.618624] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 11/19/2020] [Indexed: 12/21/2022] Open
Abstract
Chikungunya virus (CHIKV) is the causative agent of chikungunya fever (CHIKF) and is categorized as a(n) (re)emerging arbovirus. CHIKV has repeatedly been responsible for outbreaks that caused serious economic and public health problems in the affected countries. To date, no vaccine or specific antiviral therapies are available. This review gives a summary on current antivirals that have been investigated as potential therapeutics against CHIKF. The mode of action as well as possible compound targets (viral and host targets) are being addressed. This review hopes to provide critical information on the in vitro efficacies of various compounds and might help researchers in their considerations for future experiments.
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20
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Two Sides of a Coin: a Zika Virus Mutation Selected in Pregnant Rhesus Macaques Promotes Fetal Infection in Mice but at a Cost of Reduced Fitness in Nonpregnant Macaques and Diminished Transmissibility by Vectors. J Virol 2020; 94:JVI.01605-20. [PMID: 32999034 PMCID: PMC7925200 DOI: 10.1128/jvi.01605-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 09/24/2020] [Indexed: 01/05/2023] Open
Abstract
Although Zika virus infection of pregnant women can result in congenital Zika syndrome, the factors that cause the syndrome in some but not all infected mothers are still unclear. We identified a mutation that was present in some ZIKV genomes in experimentally inoculated pregnant rhesus macaques and their fetuses. Although we did not find an association between the presence of the mutation and fetal death, we performed additional studies with ZIKV with the mutation in nonpregnant macaques, pregnant mice, and mosquitoes. We observed that the mutation increased the ability of the virus to infect mouse fetuses but decreased its capacity to produce high levels of virus in the blood of nonpregnant macaques and to be transmitted by mosquitoes. This study shows that mutations in mosquito-borne viruses like ZIKV that increase fitness in pregnant vertebrates may not spread in outbreaks when they compromise transmission via mosquitoes and fitness in nonpregnant hosts. Although fetal death is now understood to be a severe outcome of congenital Zika syndrome, the role of viral genetics is still unclear. We sequenced Zika virus (ZIKV) from a rhesus macaque fetus that died after inoculation and identified a single intrahost substitution, M1404I, in the ZIKV polyprotein, located in nonstructural protein 2B (NS2B). Targeted sequencing flanking position 1404 in 9 additional macaque mothers and their fetuses identified M1404I at a subconsensus frequency in the majority (5 of 9, 56%) of animals and some of their fetuses. Despite its repeated presence in pregnant macaques, M1404I has occurred rarely in humans since 2015. Since the primary ZIKV transmission cycle is human-mosquito-human, mutations in one host must be retained in the alternate host to be perpetuated. We hypothesized that ZIKV I1404 increases viral fitness in nonpregnant macaques and pregnant mice but is less efficiently transmitted by vectors, explaining its low frequency in humans during outbreaks. By examining competitive fitness relative to that of ZIKV M1404, we observed that ZIKV I1404 produced lower viremias in nonpregnant macaques and was a weaker competitor in tissues. In pregnant wild-type mice, ZIKV I1404 increased the magnitude and rate of placental infection and conferred fetal infection, in contrast to ZIKV M1404, which was not detected in fetuses. Although infection and dissemination rates were not different, Aedes aegypti mosquitoes transmitted ZIKV I1404 more poorly than ZIKV M1404. Our data highlight the complexity of arbovirus mutation-fitness dynamics and suggest that intrahost ZIKV mutations capable of augmenting fitness in pregnant vertebrates may not necessarily spread efficiently via mosquitoes during epidemics. IMPORTANCE Although Zika virus infection of pregnant women can result in congenital Zika syndrome, the factors that cause the syndrome in some but not all infected mothers are still unclear. We identified a mutation that was present in some ZIKV genomes in experimentally inoculated pregnant rhesus macaques and their fetuses. Although we did not find an association between the presence of the mutation and fetal death, we performed additional studies with ZIKV with the mutation in nonpregnant macaques, pregnant mice, and mosquitoes. We observed that the mutation increased the ability of the virus to infect mouse fetuses but decreased its capacity to produce high levels of virus in the blood of nonpregnant macaques and to be transmitted by mosquitoes. This study shows that mutations in mosquito-borne viruses like ZIKV that increase fitness in pregnant vertebrates may not spread in outbreaks when they compromise transmission via mosquitoes and fitness in nonpregnant hosts.
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21
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Fu JYL, Chua CL, Vythilingam I, Sulaiman WYW, Wong HV, Chan YF, Sam IC. An amino acid change in nsP4 of chikungunya virus confers fitness advantage in human cell lines rather than in Aedes albopictus. J Gen Virol 2020; 100:1541-1553. [PMID: 31613205 DOI: 10.1099/jgv.0.001338] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chikungunya virus (CHIKV) has caused large-scale epidemics of fever, rash and arthritis since 2004. This unprecedented re-emergence has been associated with mutations in genes encoding structural envelope proteins, providing increased fitness in the secondary vector Aedes albopictus. In the 2008-2013 CHIKV outbreaks across Southeast Asia, an R82S mutation in non-structural protein 4 (nsP4) emerged early in Malaysia or Singapore and quickly became predominant. To determine whether this nsP4-R82S mutation provides a selective advantage in host cells, which may have contributed to the epidemic, the fitness of infectious clone-derived CHIKV with wild-type nsP4-82R and mutant nsP4-82S were compared in Ae. albopictus and human cell lines. Viral infectivity, dissemination and transmission in Ae. albopictus were not affected by the mutation when the two variants were tested separately. In competition, the nsP4-82R variant showed an advantage over nsP4-82S in dissemination to the salivary glands, but only in late infection (10 days). In human rhabdomyosarcoma (RD) and embryonic kidney (HEK-293T) cell lines coinfected at a 1 : 1 ratio, wild-type nsP4-82R virus was rapidly outcompeted by nsP4-82S virus as early as one passage (3 days). In conclusion, the nsP4-R82S mutation provides a greater selective advantage in human cells than in Ae. albopictus, which may explain its apparent natural selection during CHIKV spread in Southeast Asia. This is an unusual example of a naturally occurring mutation in a non-structural protein, which may have facilitated epidemic transmission of CHIKV.
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Affiliation(s)
- Jolene Yin Ling Fu
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Chong Long Chua
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Indra Vythilingam
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Wan Yusoff Wan Sulaiman
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Hui Vern Wong
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Yoke Fun Chan
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - I-Ching Sam
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
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22
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Abstract
The evolutionary dynamics of a virus can differ within hosts and across populations. Studies of within-host evolution provide an important link between experimental studies of virus evolution and large-scale phylodynamic analyses. They can determine the extent to which global processes are recapitulated on local scales and how accurately experimental infections model natural ones. They may also inform epidemiologic models of disease spread and reveal how host-level dynamics contribute to a virus's evolution at a larger scale. Over the last decade, advances in viral sequencing have enabled detailed studies of viral genetic diversity within hosts. I review how within-host diversity is sampled, measured, and expressed, and how comparative studies of viral diversity can be leveraged to elucidate a virus's evolutionary dynamics. These concepts are illustrated with detailed reviews of recent research on the within-host evolution of influenza virus, dengue virus, and cytomegalovirus.
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Affiliation(s)
- Adam S Lauring
- Division of Infectious Diseases, Department of Internal Medicine, and Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA;
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23
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Patterson EI, Khanipov K, Swetnam DM, Walsdorf S, Kautz TF, Thangamani S, Fofanov Y, Forrester NL. Measuring Alphavirus Fidelity Using Non-Infectious Virus Particles. Viruses 2020; 12:v12050546. [PMID: 32429270 PMCID: PMC7291308 DOI: 10.3390/v12050546] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/06/2020] [Accepted: 05/13/2020] [Indexed: 01/17/2023] Open
Abstract
Mutations are incorporated into the genomes of RNA viruses at an optimal frequency and altering this precise frequency has been proposed as a strategy to create live-attenuated vaccines. However, determining the effect of specific mutations that alter fidelity has been difficult because of the rapid selection of the virus population during replication. By deleting residues of the structural polyprotein PE2 cleavage site, E3Δ56-59, in Venezuelan equine encephalitis virus (VEEV) TC-83 vaccine strain, non-infectious virus particles were used to assess the effect of single mutations on mutation frequency without the interference of selection that results from multiple replication cycles. Next-generation sequencing analysis revealed a significantly lower frequency of transversion mutations and overall mutation frequency for the fidelity mutants compared to VEEV TC-83 E3Δ56-59. We demonstrate that deletion of the PE2 cleavage site halts virus infection while making the virus particles available for downstream sequencing. The conservation of the site will allow the evaluation of suspected fidelity mutants across alphaviruses of medical importance.
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Affiliation(s)
- Edward I. Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
- Centre for Neglected Tropical Diseases, Departments of Vector Biology and Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Correspondence:
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA; (K.K.); (Y.F.)
| | - Daniele M. Swetnam
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616, USA;
| | - Samantha Walsdorf
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
| | - Tiffany F. Kautz
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA;
| | - Saravanan Thangamani
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
| | - Yuriy Fofanov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA; (K.K.); (Y.F.)
| | - Naomi L. Forrester
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA; (S.W.); (S.T.); (N.L.F.)
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Quasispecies dynamics in disease prevention and control. VIRUS AS POPULATIONS 2020. [PMCID: PMC7153035 DOI: 10.1016/b978-0-12-816331-3.00008-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Medical interventions to prevent and treat viral disease constitute evolutionary forces that may modify the genetic composition of viral populations that replicate in an infected host and influence the genomic composition of those viruses that are transmitted and progress at the epidemiological level. Given the adaptive potential of viruses in general and the RNA viruses in particular, the selection of viral mutants that display some degree of resistance to inhibitors or vaccines is a tangible challenge. Mutant selection may jeopardize control of the viral disease. Strategies intended to minimize vaccination and treatment failures are proposed and justified based on fundamental features of viral dynamics explained in the preceding chapters. The recommended use of complex, multiepitopic vaccines, and combination therapies as early as possible after initiation of infection falls under the general concept that complexity cannot be combated with simplicity. It also follows that sociopolitical action to interrupt virus replication and spread as soon as possible is as important as scientifically sound treatment designs to control viral disease on a global scale.
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Abstract
Genetic variation is a necessity of all biological systems. Viruses use all known mechanisms of variation; mutation, several forms of recombination, and segment reassortment in the case of viruses with a segmented genome. These processes are intimately connected with the replicative machineries of viruses, as well as with fundamental physical-chemical properties of nucleotides when acting as template or substrate residues. Recombination has been viewed as a means to rescue viable genomes from unfit parents or to produce large modifications for the exploration of phenotypic novelty. All types of genetic variation can act conjointly as blind processes to provide the raw materials for adaptation to the changing environments in which viruses must replicate. A distinction is made between mechanistically unavoidable and evolutionarily relevant mutation and recombination.
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RNA-Dependent RNA Polymerase Speed and Fidelity are not the Only Determinants of the Mechanism or Efficiency of Recombination. Genes (Basel) 2019; 10:genes10120968. [PMID: 31775299 PMCID: PMC6947342 DOI: 10.3390/genes10120968] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/14/2019] [Accepted: 11/21/2019] [Indexed: 01/05/2023] Open
Abstract
Using the RNA-dependent RNA polymerase (RdRp) from poliovirus (PV) as our model system, we have shown that Lys-359 in motif-D functions as a general acid in the mechanism of nucleotidyl transfer. A K359H (KH) RdRp derivative is slow and faithful relative to wild-type enzyme. In the context of the KH virus, RdRp-coding sequence evolves, selecting for the following substitutions: I331F (IF, motif-C) and P356S (PS, motif-D). We have evaluated IF-KH, PS-KH, and IF-PS-KH viruses and enzymes. The speed and fidelity of each double mutant are equivalent. Each exhibits a unique recombination phenotype, with IF-KH being competent for copy-choice recombination and PS-KH being competent for forced-copy-choice recombination. Although the IF-PS-KH RdRp exhibits biochemical properties within twofold of wild type, the virus is impaired substantially for recombination in cells. We conclude that there are biochemical properties of the RdRp in addition to speed and fidelity that determine the mechanism and efficiency of recombination. The interwoven nature of speed, fidelity, the undefined property suggested here, and recombination makes it impossible to attribute a single property of the RdRp to fitness. However, the derivatives described here may permit elucidation of the importance of recombination on the fitness of the viral population in a background of constant polymerase speed and fidelity.
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Chikungunya virus populations experience diversity- dependent attenuation and purifying intra-vector selection in Californian Aedes aegypti mosquitoes. PLoS Negl Trop Dis 2019; 13:e0007853. [PMID: 31751338 PMCID: PMC6894883 DOI: 10.1371/journal.pntd.0007853] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 12/05/2019] [Accepted: 10/16/2019] [Indexed: 12/15/2022] Open
Abstract
Chikungunya virus (Togaviridae, Alphavirus; CHIKV) is a mosquito-borne global health threat that has been transmitted transiently in the southeastern United States. A primary CHIKV mosquito vector, Aedes aegypti, was recently established in the populous state of California, but the vector competence of Californian mosquitoes is unknown. Explosive CHIKV epidemics since 2004 have been associated with the acquisition of mosquito-adaptive mutations that enhance transmission by Ae. aegypti or Ae. albopictus. As a highly mutable RNA virus, CHIKV has the potential for extensive and rapid genetic diversification in vertebrate hosts and mosquito vectors. We previously demonstrated that expansion of CHIKV diversity in cell culture allows for greater adaptability to novel selection pressures, and that CHIKV fidelity variants are able to diversify more than wildtype (WT) CHIKV in mice. The evolution of intra-vector CHIKV populations and the correlation between CHIKV population diversity and infectivity and transmissibility in mosquitoes has not yet been studied. Here, we address these gaps in knowledge via experimental infection of Ae. aegypti from California with WT and fidelity variant CHIKV. We show that Ae. aegypti from California are highly competent vectors for CHIKV. We also report that CHIKV fidelity variants diversify more than WT in mosquitoes and exhibit attenuated infectivity at the level of the midgut. Furthermore, we demonstrate that intra-vector populations of CHIKV are subjected to purifying selection in mosquito bodies, and sequences of non-coding CHIKV regions are highly conserved. These findings will inform public health risk assessment for CHIKV in California and improve our understanding of constraints to CHIKV evolution in mosquitoes. Chikungunya virus (CHIKV) is transmitted by Aedes aegypti mosquitoes and has caused explosive epidemics in Asia and the Americas since 2004. During mosquito infection, the CHIKV genome replicates with a high mutation rate to produce virus populations with high genetic diversity that facilitate virus evolution. With this study, we address three gaps in knowledge: 1) are Ae. aegypti mosquitoes from Los Angeles, California, capable of transmitting CHIKV, 2) what effect does increased CHIKV population diversity have on virus infection and transmission by mosquitoes, and 3) are there constraints to CHIKV evolution in mosquitoes? We use oral infection of Ae. aegypti mosquitoes originating from Los Angeles, California to demonstrate high laboratory transmission competence of CHIKV. We also show that oral infection of mosquitoes with CHIKV variants that produce more diverse populations are less able to infect mosquitoes than wildtype CHIKV populations. Lastly, our study provides evidence of genome-wide and regional constraints to CHIKV evolution within Ae. aegypti mosquitoes. Our results will inform public health risk assessments for potential CHIKV introduction in southern California and advance our understanding of the role of mosquitoes in CHIKV evolution.
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Tyr82 Amino Acid Mutation in PB1 Polymerase Induces an Influenza Virus Mutator Phenotype. J Virol 2019; 93:JVI.00834-19. [PMID: 31462570 DOI: 10.1128/jvi.00834-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 08/19/2019] [Indexed: 01/16/2023] Open
Abstract
In various positive-sense single-stranded RNA viruses, a low-fidelity viral RNA-dependent RNA polymerase (RdRp) confers attenuated phenotypes by increasing the mutation frequency. We report a negative-sense single-stranded RNA virus RdRp mutant strain with a mutator phenotype. Based on structural data of RdRp, rational targeting of key residues, and screening of fidelity variants, we isolated a novel low-fidelity mutator strain of influenza virus that harbors a Tyr82-to-Cys (Y82C) single-amino-acid substitution in the PB1 polymerase subunit. The purified PB1-Y82C polymerase indeed showed an increased frequency of misincorporation compared with the wild-type PB1 in an in vitro biochemical assay. To further investigate the effects of position 82 on PB1 polymerase fidelity, we substituted various amino acids at this position. As a result, we isolated various novel mutators other than PB1-Y82C with higher mutation frequencies. The structural model of influenza virus polymerase complex suggested that the Tyr82 residue, which is located at the nucleoside triphosphate entrance tunnel, may influence a fidelity checkpoint. Interestingly, although the PB1-Y82C variant replicated with wild-type PB1-like kinetics in tissue culture, the 50% lethal dose of the PB1-Y82C mutant was 10 times lower than that of wild-type PB1 in embryonated chicken eggs. In conclusion, our data indicate that the Tyr82 residue of PB1 has a crucial role in regulating polymerase fidelity of influenza virus and is closely related to attenuated pathogenic phenotypes in vivo IMPORTANCE Influenza A virus rapidly acquires antigenic changes and antiviral drug resistance, which limit the effectiveness of vaccines and drug treatments, primarily owing to its high rate of evolution. Virus populations formed by quasispecies can contain resistance mutations even before a selective pressure is applied. To study the effects of the viral mutation spectrum and quasispecies, high- and low-fidelity variants have been isolated for several RNA viruses. Here, we report the discovery of a low-fidelity RdRp variant of influenza A virus that contains a substitution at Tyr82 in PB1. Viruses containing the PB1-Y82C substitution showed growth kinetics and viral RNA synthesis levels similar to those of the wild-type virus in cell culture; however, they had significantly attenuated phenotypes in a chicken egg infection experiment. These data demonstrated that decreased RdRp fidelity attenuates influenza A virus in vivo, which is a desirable feature for the development of safer live attenuated vaccine candidates.
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Cifuente JO, Moratorio G. Evolutionary and Structural Overview of Human Picornavirus Capsid Antibody Evasion. Front Cell Infect Microbiol 2019; 9:283. [PMID: 31482072 PMCID: PMC6710328 DOI: 10.3389/fcimb.2019.00283] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 07/24/2019] [Indexed: 11/13/2022] Open
Abstract
Picornaviruses constitute one of the most relevant viral groups according to their impact on human and animal health. Etiologic agents of a broad spectrum of illnesses with a clinical presentation that ranges from asymptomatic to fatal disease, they have been the cause of uncountable epidemics throughout history. Picornaviruses are small naked RNA-positive single-stranded viruses that include some of the most important pillars in the development of virology, comprising poliovirus, rhinovirus, and hepatitis A virus. Picornavirus infectious particles use the fecal-oral or respiratory routes as primary modes of transmission. In this regard, successful viral spread relies on the capability of viral capsids to (i) shelter the viral genome, (ii) display molecular determinants for cell receptor recognition, (iii) facilitate efficient genome delivery, and (iv) escape from the immune system. Importantly, picornaviruses display a substantial amount of genetic variability driven by both mutation and recombination. Therefore, the outcome of their replication results in the emergence of a genetically diverse cloud of individuals presenting phenotypic variance. The host humoral response against the capsid protein represents the most active immune pressure and primary weapon to control the infection. Since the preservation of the capsid function is deeply rooted in the virus evolutionary dynamics, here we review the current structural evidence focused on capsid antibody evasion mechanisms from that perspective.
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Affiliation(s)
| | - Gonzalo Moratorio
- Laboratorio de Virología Molecular, Centro de Investigaciones Nucleares, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.,Laboratorio de Inmunovirología, Institut Pasteur de Montevideo, Montevideo, Uruguay
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Liu J, Swevers L, Kolliopoulou A, Smagghe G. Arboviruses and the Challenge to Establish Systemic and Persistent Infections in Competent Mosquito Vectors: The Interaction With the RNAi Mechanism. Front Physiol 2019; 10:890. [PMID: 31354527 PMCID: PMC6638189 DOI: 10.3389/fphys.2019.00890] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 06/27/2019] [Indexed: 12/15/2022] Open
Abstract
Arboviruses are capable to establish long-term persistent infections in mosquitoes that do not affect significantly the physiology of the insect vectors. Arbovirus infections are controlled by the RNAi machinery via the production of viral siRNAs and the formation of RISC complexes targeting viral genomes and mRNAs. Engineered arboviruses that contain cellular gene sequences can therefore be transformed to "viral silencing vectors" for studies of gene function in reverse genetics approaches. More specifically, "ideal" viral silencing vectors must be competent to induce robust RNAi effects while other interactions with the host immune system should be kept at a minimum to reduce non-specific effects. Because of their inconspicuous nature, arboviruses may approach the "ideal" viral silencing vectors in insects and it is therefore worthwhile to study the mechanisms by which the interactions with the RNAi machinery occur. In this review, an analysis is presented of the antiviral RNAi response in mosquito vectors with respect to the major types of arboviruses (alphaviruses, flaviviruses, bunyaviruses, and others). With respect to antiviral defense, the exo-RNAi pathway constitutes the major mechanism while the contribution of both miRNAs and viral piRNAs remains a contentious issue. However, additional mechanisms exist in mosquitoes that are capable to enhance or restrict the efficiency of viral silencing vectors such as the amplification of RNAi effects by DNA forms, the existence of incorporated viral elements in the genome and the induction of a non-specific systemic response by Dicer-2. Of significance is the observation that no major "viral suppressors of RNAi" (VSRs) seem to be encoded by arboviral genomes, indicating that relatively tight control of the activity of the RNA-dependent RNA polymerase (RdRp) may be sufficient to maintain the persistent character of arbovirus infections. Major strategies for improvement of viral silencing vectors therefore are proposed to involve engineering of VSRs and modifying of the properties of the RdRp. Because of safety issues (pathogen status), however, arbovirus-based silencing vectors are not well suited for practical applications, such as RNAi-based mosquito control. In that case, related mosquito-specific viruses that also establish persistent infections and may cause similar RNAi responses may represent a valuable alternative solution.
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Affiliation(s)
- Jisheng Liu
- School of Life Sciences, Guangzhou University, Guangzhou, China
| | - Luc Swevers
- Institute of Biosciences and Applications, National Centre of Scientific Research “Demokritos”, Athens, Greece
| | - Anna Kolliopoulou
- Institute of Biosciences and Applications, National Centre of Scientific Research “Demokritos”, Athens, Greece
| | - Guy Smagghe
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Defective viral genomes are key drivers of the virus-host interaction. Nat Microbiol 2019; 4:1075-1087. [PMID: 31160826 PMCID: PMC7097797 DOI: 10.1038/s41564-019-0465-y] [Citation(s) in RCA: 182] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 04/23/2019] [Indexed: 12/12/2022]
Abstract
Viruses survive often harsh host environments, yet we know little about the strategies they utilize to adapt and subsist given their limited genomic resources. We are beginning to appreciate the surprising versatility of viral genomes and how replication-competent and -defective virus variants can provide means for adaptation, immune escape and virus perpetuation. This Review summarizes current knowledge of the types of defective viral genomes generated during the replication of RNA viruses and the functions that they carry out. We highlight the universality and diversity of defective viral genomes during infections and discuss their predicted role in maintaining a fit virus population, their impact on human and animal health, and their potential to be harnessed as antiviral tools. This Review describes recent findings on the biogenesis and the role of defective viral genomes during replication of RNA viruses and discusses their impact on viral dynamics and evolution.
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Atovaquone Inhibits Arbovirus Replication through the Depletion of Intracellular Nucleotides. J Virol 2019; 93:JVI.00389-19. [PMID: 30894466 DOI: 10.1128/jvi.00389-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 03/13/2019] [Indexed: 12/11/2022] Open
Abstract
Arthropod-borne viruses represent a significant public health threat worldwide, yet there are few antiviral therapies or prophylaxes targeting these pathogens. In particular, the development of novel antivirals for high-risk populations such as pregnant women is essential to prevent devastating disease such as that which was experienced with the recent outbreak of Zika virus (ZIKV) in the Americas. One potential avenue to identify new and pregnancy-acceptable antiviral compounds is to repurpose well-known and widely used FDA-approved drugs. In this study, we addressed the antiviral role of atovaquone, an FDA Pregnancy Category C drug and pyrimidine biosynthesis inhibitor used for the prevention and treatment of parasitic infections. We found that atovaquone was able to inhibit ZIKV and chikungunya virus virion production in human cells and that this antiviral effect occurred early during infection at the initial steps of viral RNA replication. Moreover, we were able to complement viral replication and virion production with the addition of exogenous pyrimidine nucleosides, indicating that atovaquone functions through the inhibition of the pyrimidine biosynthesis pathway to inhibit viral replication. Finally, using an ex vivo human placental tissue model, we found that atovaquone could limit ZIKV infection in a dose-dependent manner, providing evidence that atovaquone may function as an antiviral in humans. Taken together, these studies suggest that atovaquone could be a broad-spectrum antiviral drug and a potential attractive candidate for the prophylaxis or treatment of arbovirus infection in vulnerable populations, such as pregnant women and children.IMPORTANCE The ability to protect vulnerable populations such as pregnant women and children from Zika virus and other arbovirus infections is essential to preventing the devastating complications induced by these viruses. One class of antiviral therapies may lie in known pregnancy-acceptable drugs that have the potential to mitigate arbovirus infections and disease, yet this has not been explored in detail. In this study, we show that the common antiparasitic drug atovaquone inhibits arbovirus replication through intracellular nucleotide depletion and can impair ZIKV infection in an ex vivo human placental explant model. Our study provides a novel function for atovaquone and highlights that the rediscovery of pregnancy-acceptable drugs with potential antiviral effects can be the key to better addressing the immediate need for treating viral infections and preventing potential birth complications and future disease.
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Riemersma KK, Steiner C, Singapuri A, Coffey LL. Chikungunya Virus Fidelity Variants Exhibit Differential Attenuation and Population Diversity in Cell Culture and Adult Mice. J Virol 2019; 93:e01606-18. [PMID: 30429348 PMCID: PMC6340026 DOI: 10.1128/jvi.01606-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 11/05/2018] [Indexed: 12/31/2022] Open
Abstract
Chikungunya virus (CHIKV) is a reemerging global health threat that produces debilitating arthritis in people. Like other RNA viruses with high mutation rates, CHIKV produces populations of genetically diverse genomes within a host. While several known CHIKV mutations influence disease severity in vertebrates and transmission by mosquitoes, the role of intrahost diversity in chikungunya arthritic disease has not been studied. In this study, high- and low-fidelity CHIKV variants, previously characterized by altered in vitro population mutation frequencies, were used to evaluate how intrahost diversity influences clinical disease, CHIKV replication, and antibody neutralization in immunocompetent adult mice inoculated in the rear footpads. Both high- and low-fidelity mutations were hypothesized to attenuate CHIKV arthritic disease, replication, and neutralizing antibody levels compared to wild-type (WT) CHIKV. Unexpectedly, high-fidelity mutants elicited more severe arthritic disease than the WT despite comparable CHIKV replication, whereas a low-fidelity mutant produced attenuated disease and replication. Serum antibody developed against both high- and low-fidelity CHIKV exhibited reduced neutralization of WT CHIKV. Using next-generation sequencing (NGS), the high-fidelity mutations were demonstrated to be genetically stable but produced more genetically diverse populations than WT CHIKV in mice. This enhanced diversification was subsequently reproduced after serial in vitro passage. The NGS results contrast with previously reported population diversities for fidelity variants, which focused mainly on part of the E1 gene, and highlight the need for direct measurements of mutation rates to clarify CHIKV fidelity phenotypes.IMPORTANCE CHIKV is a reemerging global health threat that elicits debilitating arthritis in humans. There are currently no commercially available CHIKV vaccines. Like other RNA viruses, CHIKV has a high mutation rate and is capable of rapid intrahost diversification during an infection. In other RNA viruses, virus population diversity associates with disease progression; however, potential impacts of intrahost viral diversity on CHIKV arthritic disease have not been studied. Using previously characterized CHIKV fidelity variants, we addressed whether CHIKV population diversity influences the severity of arthritis and host antibody response in an arthritic mouse model. Our findings show that CHIKV populations with greater genetic diversity can cause more severe disease and stimulate antibody responses with reduced neutralization of low-diversity virus populations in vitro The discordant high-fidelity phenotypes in this study highlight the complexity of inferring replication fidelity indirectly from population diversity.
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Affiliation(s)
- Kasen K Riemersma
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Cody Steiner
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Anil Singapuri
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Lark L Coffey
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, California, USA
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Zhao W, Wang Q, Xu Z, Liu R, Cui F. Immune responses induced by different genotypes of the disease-specific protein of Rice stripe virus in the vector insect. Virology 2019; 527:122-131. [PMID: 30500711 DOI: 10.1016/j.virol.2018.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/15/2018] [Accepted: 11/17/2018] [Indexed: 01/25/2023]
Abstract
Persistent plant viruses circulate between host plants and vector insects, possibly leading to the genetic divergence in viral populations. We analyzed the single nucleotide polymorphisms (SNPs) of Rice stripe virus (RSV) when it incubated in the small brown planthopper and rice. Two SNPs, which lead to nonsynonymous substitutions in the disease-specific protein (SP) of RSV, produced three genotypes, i.e., GG, AA and GA. The GG type mainly existed in the early infection period of RSV in the planthoppers and was gradually substituted by the other two genotypes during viral transmission. The two SNPs did not affect the interactions of SP with rice PsbP or with RSV coat protein. The GG genotype of SP induced stronger immune responses than those of the other two genotypes in the pattern recognition molecule and immune-responsive effector pathways. These findings demonstrated the population variations of RSV during the circulation between the vector insect and host plant.
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Affiliation(s)
- Wan Zhao
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qianshuo Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui 230601, China
| | - Zhongtian Xu
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai 201602, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Renyi Liu
- Center for Agroforestry Mega Data Science and FAFU-UCR Joint Center for Horticultural Biology and Metabolomics, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Feng Cui
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
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Muñoz-Medina JE, Garcia-Knight MA, Sanchez-Flores A, Monroy-Muñoz IE, Grande R, Esbjörnsson J, Santacruz-Tinoco CE, González-Bonilla CR. Evolutionary analysis of the Chikungunya virus epidemic in Mexico reveals intra-host mutational hotspots in the E1 protein. PLoS One 2018; 13:e0209292. [PMID: 30550577 PMCID: PMC6294367 DOI: 10.1371/journal.pone.0209292] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 12/03/2018] [Indexed: 12/22/2022] Open
Abstract
The epidemic potential of Chikungunya virus (CHIKV) was recently made evident by its introduction and rapid expansion in the Caribbean and the Americas. We sought to gain a detailed understanding of the dynamics of the epidemic in Mexico, the country with the highest number of confirmed CHIKV cases in the Americas, and to characterise viral evolution at the population and intra-host level. Analysis of the spatiotemporal distribution of 2,739 diagnosed cases in Mexico from December 2014 to December 2015 showed a rapid nationwide expansion of the epidemic with focalisation in the South West of the country. We sequenced the envelope glycoprotein 1 gene (E1) from 25 patients using the Illumina MiSeq platform and report synonymous and non-synonymous consensus mutations. Bayesian phylogenetic analysis using 249 Asian lineage E1 sequences gave updated estimates of nucleotide substitution rates for E1 and time to most recent common ancestor of major lineages. The analysis indicates phylogenetically-related emergent Latin American clusters in South Western Mexico, Nicaragua and Honduras and transmission of American strains in the Pacific islands. Detailed analysis showed that intra-host changes in E1 mainly occurred in two variable regions (E1:189-220 and E1:349-358) in domains II and III, respectively, in residues involved in inter and intra-envelope spike interactions. At the population level, this study sheds light on the introduction and evolutionary dynamics of CHIKV in the Americas. At the intra-host level, this study identifies mutational hotspots of the E1 protein with implications for understanding the relationship between the CHIKV quasispecies, viral fitness and pathogenesis.
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Affiliation(s)
- José Esteban Muñoz-Medina
- Laboratorio Central de Epidemiología, Centro Médico Nacional “La Raza”, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Miguel Antonio Garcia-Knight
- Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Alejandro Sanchez-Flores
- Unidad Universitaria de Secuenciación Masiva y Bioinformática, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Irma Eloísa Monroy-Muñoz
- Laboratorio de Genómica, Departamento de Genética y Genómica Humana, Instituto Nacional de Perinatología “Isidro Espinosa de los Reyes”, Mexico City, México
| | - Ricardo Grande
- Unidad Universitaria de Secuenciación Masiva y Bioinformática, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Joakim Esbjörnsson
- Systems Virology, Department of Laboratory Medicine, Lund University, Lund, Sweden
- NDM Research Building, Nuffield Department Medicine, University of Oxford, Oxford, United Kingdom
| | - Clara Esperanza Santacruz-Tinoco
- Laboratorio Central de Epidemiología, Centro Médico Nacional “La Raza”, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - César Raúl González-Bonilla
- División de Laboratorios de Vigilancia e Investigación Epidemiológica, Instituto Mexicano del Seguro Social, Mexico City, Mexico
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RNA Virus Fidelity Mutants: A Useful Tool for Evolutionary Biology or a Complex Challenge? Viruses 2018; 10:v10110600. [PMID: 30388745 PMCID: PMC6267201 DOI: 10.3390/v10110600] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 12/30/2022] Open
Abstract
RNA viruses replicate with low fidelity due to the error-prone nature of the RNA-dependent RNA polymerase, which generates approximately one mutation per round of genome replication. Due to the large population sizes produced by RNA viruses during replication, this results in a cloud of closely related virus variants during host infection, of which small increases or decreases in replication fidelity have been shown to result in virus attenuation in vivo, but not typically in vitro. Since the discovery of the first RNA virus fidelity mutants during the mid-aughts, the field has exploded with the identification of over 50 virus fidelity mutants distributed amongst 7 RNA virus families. This review summarizes the current RNA virus fidelity mutant literature, with a focus upon the definition of a fidelity mutant as well as methods to confirm any mutational changes associated with the fidelity mutant. Due to the complexity of such a definition, in addition to reports of unstable virus fidelity phenotypes, the future translational utility of these mutants and applications for basic science are examined.
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Abstract
With the advent of advanced sequencing technology, studies of RNA viruses have shown that genetic diversity can contribute to both attenuation and virulence and the paradigm is that this is controlled by the error-prone RNA-dependent RNA polymerase (RdRp). Since wild-type yellow fever virus (YFV) strain Asibi has genetic diversity typical of a wild-type RNA virus, while 17D virus vaccine has limited diversity, it provides a unique opportunity to investigate RNA population theory in the context of a well-characterized live attenuated vaccine. Utilizing infectious clone-derived viruses, we show that genetic diversity of RNA viruses is complex and that multiple genes, including structural genes and NS2B and NS4B genes also contribute to genetic diversity. We suggest that the replication complex as a whole, rather than only RdRp, drives genetic diversity, at least for YFV. One paradigm to explain the complexity of viral RNA populations is that the low fidelity of the RNA-dependent RNA polymerase (RdRp) drives high mutation rates and consequently genetic diversity. Like most RNA viruses, wild-type yellow fever virus (YFV) replication is error-prone due to the lack of proofreading by the virus-encoded RdRp. However, there is evidence that replication of the live attenuated YF vaccine virus 17D, derived from wild-type strain Asibi, is less error-prone than wild-type RNA viruses. Recent studies comparing the genetic diversity of wild-type Asibi and 17D vaccine virus found that wild-type Asibi has the typical heterogeneous population of an RNA virus, while there is limited intra- and interpopulation variability of 17D vaccine virus. Utilizing chimeric and mutant infectious clone-derived viruses, we show that high and low genetic diversity profiles of wild-type Asibi virus and vaccine virus 17D, respectively, are multigenic. Introduction of either structural (pre-membrane and envelope) genes or NS2B or NS4B substitutions into the Asibi and 17D backbone resulted in altered variant population, nucleotide diversity, and mutation frequency compared to the parental viruses. Additionally, changes in genetic diversity of the chimeric and mutant viruses correlated with the phenotype of multiplication kinetics in human alveolar A549 cells. Overall, the paradigm that only the error-prone RdRp controls genetic diversity needs to be expanded to address the role of other genes in genetic diversity, and we hypothesize that it is the replication complex as a whole and not the RdRp alone that controls genetic diversity.
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Dolan PT, Whitfield ZJ, Andino R. Mechanisms and Concepts in RNA Virus Population Dynamics and Evolution. Annu Rev Virol 2018; 5:69-92. [PMID: 30048219 DOI: 10.1146/annurev-virology-101416-041718] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
RNA viruses are unique in their evolutionary capacity, exhibiting high mutation rates and frequent recombination. They rapidly adapt to environmental changes, such as shifts in immune pressure or pharmacological challenge. The evolution of RNA viruses has been brought into new focus with the recent developments of genetic and experimental tools to explore and manipulate the evolutionary dynamics of viral populations. These studies have uncovered new mechanisms that enable viruses to overcome evolutionary challenges in the environment and have emphasized the intimate relationship of viral populations with evolution. Here, we review some of the emerging viral and host mechanisms that underlie the evolution of RNA viruses. We also discuss new studies that demonstrate that the relationship between evolutionary dynamics and virus biology spans many spatial and temporal scales, affecting transmission dynamics within and between hosts as well as pathogenesis.
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Affiliation(s)
- Patrick T Dolan
- Department of Biology, Stanford University, Stanford, California 94305, USA.,Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA;
| | - Zachary J Whitfield
- Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA;
| | - Raul Andino
- Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA;
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Fitzsimmons WJ, Woods RJ, McCrone JT, Woodman A, Arnold JJ, Yennawar M, Evans R, Cameron CE, Lauring AS. A speed-fidelity trade-off determines the mutation rate and virulence of an RNA virus. PLoS Biol 2018; 16:e2006459. [PMID: 29953453 PMCID: PMC6040757 DOI: 10.1371/journal.pbio.2006459] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/11/2018] [Accepted: 06/12/2018] [Indexed: 11/18/2022] Open
Abstract
Mutation rates can evolve through genetic drift, indirect selection due to genetic hitchhiking, or direct selection on the physicochemical cost of high fidelity. However, for many systems, it has been difficult to disentangle the relative impact of these forces empirically. In RNA viruses, an observed correlation between mutation rate and virulence has led many to argue that their extremely high mutation rates are advantageous because they may allow for increased adaptability. This argument has profound implications because it suggests that pathogenesis in many viral infections depends on rare or de novo mutations. Here, we present data for an alternative model whereby RNA viruses evolve high mutation rates as a byproduct of selection for increased replicative speed. We find that a poliovirus antimutator, 3DG64S, has a significant replication defect and that wild-type (WT) and 3DG64S populations have similar adaptability in 2 distinct cellular environments. Experimental evolution of 3DG64S under selection for replicative speed led to reversion and compensation of the fidelity phenotype. Mice infected with 3DG64S exhibited delayed morbidity at doses well above the lethal level, consistent with attenuation by slower growth as opposed to reduced mutational supply. Furthermore, compensation of the 3DG64S growth defect restored virulence, while compensation of the fidelity phenotype did not. Our data are consistent with the kinetic proofreading model for biosynthetic reactions and suggest that speed is more important than accuracy. In contrast with what has been suggested for many RNA viruses, we find that within-host spread is associated with viral replicative speed and not standing genetic diversity. Why organisms have different mutation rates is a longstanding question in evolutionary biology. The polymerases of RNA viruses generally lack proofreading activity and exhibit extremely high mutation rates. Because most mutations are deleterious and mutation rates are typically tuned by natural selection, we asked why RNA viruses haven’t evolved a polymerase with a lower mutation rate. We used experimental evolution and a murine infection model to show that RNA virus mutation rates may actually be too high and are not necessarily adaptive. Rather, our data indicate that viral mutation rates have evolved to be higher as a result of selection for viruses with faster replication kinetics. We suggest that viruses have high mutation rates, not because they facilitate adaptation but because it is hard to be both fast and accurate and these viruses have prioritized speed over fidelity.
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Affiliation(s)
- William J. Fitzsimmons
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Robert J. Woods
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - John T. McCrone
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Andrew Woodman
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Jamie J. Arnold
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Madhumita Yennawar
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Richard Evans
- Department of Epidemiology, University of Michigan, Ann Arbor, Michigan United States of America
| | - Craig E. Cameron
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Adam S. Lauring
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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40
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Abstract
Reproduction of RNA viruses is typically error-prone due to the infidelity of their replicative machinery and the usual lack of proofreading mechanisms. The error rates may be close to those that kill the virus. Consequently, populations of RNA viruses are represented by heterogeneous sets of genomes with various levels of fitness. This is especially consequential when viruses encounter various bottlenecks and new infections are initiated by a single or few deviating genomes. Nevertheless, RNA viruses are able to maintain their identity by conservation of major functional elements. This conservatism stems from genetic robustness or mutational tolerance, which is largely due to the functional degeneracy of many protein and RNA elements as well as to negative selection. Another relevant mechanism is the capacity to restore fitness after genetic damages, also based on replicative infidelity. Conversely, error-prone replication is a major tool that ensures viral evolvability. The potential for changes in debilitated genomes is much higher in small populations, because in the absence of stronger competitors low-fit genomes have a choice of various trajectories to wander along fitness landscapes. Thus, low-fit populations are inherently unstable, and it may be said that to run ahead it is useful to stumble. In this report, focusing on picornaviruses and also considering data from other RNA viruses, we review the biological relevance and mechanisms of various alterations of viral RNA genomes as well as pathways and mechanisms of rehabilitation after loss of fitness. The relationships among mutational robustness, resilience, and evolvability of viral RNA genomes are discussed.
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41
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Kautz TF, Guerbois M, Khanipov K, Patterson EI, Langsjoen RM, Yun R, Warmbrod KL, Fofanov Y, Weaver SC, Forrester NL. Low-fidelity Venezuelan equine encephalitis virus polymerase mutants to improve live-attenuated vaccine safety and efficacy. Virus Evol 2018; 4:vey004. [PMID: 29593882 PMCID: PMC5841381 DOI: 10.1093/ve/vey004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During RNA virus replication, there is the potential to incorporate mutations that affect virulence or pathogenesis. For live-attenuated vaccines, this has implications for stability, as replication may result in mutations that either restore the wild-type phenotype via reversion or compensate for the attenuating mutations by increasing virulence (pseudoreversion). Recent studies have demonstrated that altering the mutation rate of an RNA virus is an effective attenuation tool. To validate the safety of low-fidelity mutations to increase vaccine attenuation, several mutations in the RNA-dependent RNA-polymerase (RdRp) were tested in the live-attenuated Venezuelan equine encephalitis virus vaccine strain, TC-83. Next generation sequencing after passage in the presence of mutagens revealed a mutant containing three mutations in the RdRp, TC-83 3x, to have decreased replication fidelity, while a second mutant, TC-83 4x displayed no change in fidelity, but shared many phenotypic characteristics with TC-83 3x. Both mutants exhibited increased, albeit inconsistent attenuation in an infant mouse model, as well as increased immunogenicity and complete protection against lethal challenge of an adult murine model compared with the parent TC-83. During serial passaging in a highly permissive model, the mutants increased in virulence but remained less virulent than the parent TC-83. These results suggest that the incorporation of low-fidelity mutations into the RdRp of live-attenuated vaccines for RNA viruses can confer increased immunogenicity whilst showing some evidence of increased attenuation. However, while in theory such constructs may result in more effective vaccines, the instability of the vaccine phenotype decreases the likelihood of this being an effective vaccine strategy.
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Affiliation(s)
- Tiffany F Kautz
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | - Mathilde Guerbois
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Edward I Patterson
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Rose M Langsjoen
- Institute for Translational Sciences, University of Texas Medical Branch, Galveston, TX, USA
| | - Ruimei Yun
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Kelsey L Warmbrod
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Yuriy Fofanov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Scott C Weaver
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA.,Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Naomi L Forrester
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
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42
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Poirier EZ, Goic B, Tomé-Poderti L, Frangeul L, Boussier J, Gausson V, Blanc H, Vallet T, Loyd H, Levi LI, Lanciano S, Baron C, Merkling SH, Lambrechts L, Mirouze M, Carpenter S, Vignuzzi M, Saleh MC. Dicer-2-Dependent Generation of Viral DNA from Defective Genomes of RNA Viruses Modulates Antiviral Immunity in Insects. Cell Host Microbe 2018; 23:353-365.e8. [PMID: 29503180 PMCID: PMC5857290 DOI: 10.1016/j.chom.2018.02.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 11/08/2017] [Accepted: 02/07/2018] [Indexed: 12/21/2022]
Abstract
The RNAi pathway confers antiviral immunity in insects. Virus-specific siRNA responses are amplified via the reverse transcription of viral RNA to viral DNA (vDNA). The nature, biogenesis, and regulation of vDNA are unclear. We find that vDNA produced during RNA virus infection of Drosophila and mosquitoes is present in both linear and circular forms. Circular vDNA (cvDNA) is sufficient to produce siRNAs that confer partially protective immunity when challenged with a cognate virus. cvDNAs bear homology to defective viral genomes (DVGs), and DVGs serve as templates for vDNA and cvDNA synthesis. Accordingly, DVGs promote the amplification of vDNA-mediated antiviral RNAi responses in infected Drosophila. Furthermore, vDNA synthesis is regulated by the DExD/H helicase domain of Dicer-2 in a mechanism distinct from its role in siRNA generation. We suggest that, analogous to mammalian RIG-I-like receptors, Dicer-2 functions like a pattern recognition receptor for DVGs to modulate antiviral immunity in insects.
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Affiliation(s)
- Enzo Z Poirier
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; University of Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, 75013 Paris, France
| | - Bertsy Goic
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Lorena Tomé-Poderti
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Lionel Frangeul
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Jérémy Boussier
- Institut Pasteur, Immunobiology of Dendritic Cells, Institut National de la Santé et de la Recherche Médicale, U1223, 75015 Paris, France
| | - Valérie Gausson
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Hervé Blanc
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France; Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Thomas Vallet
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Hyelee Loyd
- Department of Animal Science, Iowa State University, Ames, IA 50010, USA
| | - Laura I Levi
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Sophie Lanciano
- Institut de Recherche pour le Développement, DIADE, Université de Montpellier, Université de Perpignan, LGDP, 66860 Perpignan, France
| | - Chloé Baron
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France
| | - Sarah H Merkling
- Institut Pasteur, Insect-Virus Interactions, Centre National de la Recherche Scientifique URA 3012, 75015 Paris, France
| | - Louis Lambrechts
- Institut Pasteur, Insect-Virus Interactions, Centre National de la Recherche Scientifique URA 3012, 75015 Paris, France
| | - Marie Mirouze
- Institut de Recherche pour le Développement, DIADE, Université de Montpellier, Université de Perpignan, LGDP, 66860 Perpignan, France
| | - Susan Carpenter
- Department of Animal Science, Iowa State University, Ames, IA 50010, USA
| | - Marco Vignuzzi
- Institut Pasteur, Viral Populations and Pathogenesis, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France.
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR 3569, 75015 Paris, France.
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43
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Patterson EI, Khanipov K, Rojas MM, Kautz TF, Rockx-Brouwer D, Golovko G, Albayrak L, Fofanov Y, Forrester NL. Mosquito bottlenecks alter viral mutant swarm in a tissue and time-dependent manner with contraction and expansion of variant positions and diversity. Virus Evol 2018; 4:vey001. [PMID: 29479479 PMCID: PMC5814806 DOI: 10.1093/ve/vey001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Viral diversity is theorized to play a significant role during virus infections, particularly for arthropod-borne viruses (arboviruses) that must infect both vertebrate and invertebrate hosts. To determine how viral diversity influences mosquito infection and dissemination Culex taeniopus mosquitoes were infected with the Venezuelan equine encephalitis virus endemic strain 68U201. Bodies and legs/wings of the mosquitoes were collected individually and subjected to multi-parallel sequencing. Virus sequence diversity was calculated for each tissue. Greater diversity was seen in mosquitoes with successful dissemination versus those with no dissemination. Diversity across time revealed that bottlenecks influence diversity following dissemination to the legs/wings, but levels of diversity are restored by Day 12 post-dissemination. Specific minority variants were repeatedly identified across the mosquito cohort, some in nearly every tissue and time point, suggesting that certain variants are important in mosquito infection and dissemination. This study demonstrates that the interaction between the mosquito and the virus results in changes in diversity and the mutational spectrum and may be essential for successful transition of the bottlenecks associated with arbovirus infection.
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Affiliation(s)
- Edward I Patterson
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0610, USA
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555-0617, USA
| | - Mark M Rojas
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555-0617, USA
| | - Tiffany F Kautz
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0610, USA
| | - Dedeke Rockx-Brouwer
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0610, USA
| | - Georgiy Golovko
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555-0617, USA
| | - Levent Albayrak
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555-0617, USA
| | - Yuriy Fofanov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555-0617, USA
| | - Naomi L Forrester
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0610, USA
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44
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Nonstructural Proteins of Alphavirus-Potential Targets for Drug Development. Viruses 2018; 10:v10020071. [PMID: 29425115 PMCID: PMC5850378 DOI: 10.3390/v10020071] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 02/02/2018] [Accepted: 02/06/2018] [Indexed: 12/31/2022] Open
Abstract
Alphaviruses are enveloped, positive single-stranded RNA viruses, typically transmitted by arthropods. They often cause arthralgia or encephalitic diseases in infected humans and there is currently no targeted antiviral treatment available. The re-emergence of alphaviruses in Asia, Europe, and the Americas over the last decade, including chikungunya and o'nyong'nyong viruses, have intensified the search for selective inhibitors. In this review, we highlight key molecular determinants within the alphavirus replication complex that have been identified as viral targets, focusing on their structure and functionality in viral dissemination. We also summarize recent structural data of these viral targets and discuss how these could serve as templates to facilitate structure-based drug design and development of small molecule inhibitors.
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45
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Abstract
The role of intra-host genetic diversity in dengue viral populations remains a topic of debate, particularly the impact on transmission of changes in this diversity. Several approaches have been taken to increasing and decreasing the genetic diversity of populations of RNA viruses and have drawn what appear to be contradictory conclusions. A 2-6 fold increase in genetic diversity of a wild type population of dengue virus serotype 1(DENV1) and of an infectious clone population derived from the wild type population, produced by treatment with nucleotide analogue 5 fluorouracil (5FU), drove the populations to extinction. Removal of 5FU immediately prior to extinction, resulted in a return to pre-treatment levels of fitness and genetic diversity, albeit with novel single nucleotide polymorphisms. These observations support the concept that DENV populations exist on fitness peaks determined by their transmission requirements and either an increase or a decrease in genetic diversity may result in a loss of fitness.
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46
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Carrasco-Hernandez R, Jácome R, López Vidal Y, Ponce de León S. Are RNA Viruses Candidate Agents for the Next Global Pandemic? A Review. ILAR J 2017; 58:343-358. [PMID: 28985316 PMCID: PMC7108571 DOI: 10.1093/ilar/ilx026] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 07/14/2017] [Accepted: 07/15/2017] [Indexed: 12/16/2022] Open
Abstract
Pathogenic RNA viruses are potentially the most important group involved in zoonotic disease transmission, and they represent a challenge for global disease control. Their biological diversity and rapid adaptive rates have proved to be difficult to overcome and to anticipate by modern medical technology. Also, the anthropogenic change of natural ecosystems and the continuous population growth are driving increased rates of interspecies contacts and the interchange of pathogens that can develop into global pandemics. The combination of molecular, epidemiological, and ecological knowledge of RNA viruses is therefore essential towards the proper control of these emergent pathogens. This review outlines, throughout different levels of complexity, the problems posed by RNA viral diseases, covering some of the molecular mechanisms allowing them to adapt to new host species-and to novel pharmaceutical developments-up to the known ecological processes involved in zoonotic transmission.
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Affiliation(s)
- R Carrasco-Hernandez
- R. Carrasco-Hernandez, PhD, is a postdoctoral research fellow at the Microbiome Laboratory in the Postgraduate Division of the Faculty of Medicine at the Universidad Nacional Autónoma de México, CDMX
| | - Rodrigo Jácome
- Rodrigo Jácome, MD, PhD, is a postdoctoral research fellow at the Microbiome Laboratory in the Postgraduate Division of the Faculty of Medicine at the Universidad Nacional Autónoma de México, CDMX
| | - Yolanda López Vidal
- Yolanda López-Vidal, MD, PhD, is an associate professor “C” and is responsible for the Program of Microbial Molecular Immunology in the Department of Microbiology and Parasitology of the Faculty of Medicine at the Universidad Nacional Autónoma de México, CDMX
| | - Samuel Ponce de León
- Samuel Ponce-de-León, MD, MSc, is an associate professor “C”, is responsible for the Microbiome Laboratory and Coordinator of the University Program for Health Research of the Faculty of Medicine at the Universidad Nacional Autónoma de México, CDMX
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47
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Barr KL. Vertical transmission of positive-sense single-stranded RNA viruses in plants as a model for arboviral induced teratogenesis. Curr Opin Virol 2017; 27:42-47. [PMID: 29172070 DOI: 10.1016/j.coviro.2017.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/06/2017] [Accepted: 11/09/2017] [Indexed: 11/25/2022]
Abstract
Teratogenic viruses have increased public health importance with the emergence of Zika virus and a recent decline in rubella virus vaccination. Of the seven viruses known to cause birth defects in humans, three are mosquito-borne pathogens. Ethical oversight, compliance, rising costs, and the need for specialized training slow the pace of study of these human pathogens compared to study of similar teratogenic viruses in plants. Plant viruses have served as models for human viruses which can be applied to animal systems. This review describes the similar features of plant and animal teratogenic arboviruses and the common systems and barriers that are encountered during vertical transmission in the host.
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Affiliation(s)
- Kelli L Barr
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, United States.
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48
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Graepel KW, Lu X, Case JB, Sexton NR, Smith EC, Denison MR. Proofreading-Deficient Coronaviruses Adapt for Increased Fitness over Long-Term Passage without Reversion of Exoribonuclease-Inactivating Mutations. mBio 2017; 8:e01503-17. [PMID: 29114026 PMCID: PMC5676041 DOI: 10.1128/mbio.01503-17] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/10/2017] [Indexed: 12/31/2022] Open
Abstract
The coronavirus (CoV) RNA genome is the largest among the single-stranded positive-sense RNA viruses. CoVs encode a proofreading 3'-to-5' exoribonuclease within nonstructural protein 14 (nsp14-ExoN) that is responsible for CoV high-fidelity replication. Alanine substitution of ExoN catalytic residues [ExoN(-)] in severe acute respiratory syndrome-associated coronavirus (SARS-CoV) and murine hepatitis virus (MHV) disrupts ExoN activity, yielding viable mutant viruses with defective replication, up to 20-fold-decreased fidelity, and increased susceptibility to nucleoside analogues. To test the stability of the ExoN(-) genotype and phenotype, we passaged MHV-ExoN(-) 250 times in cultured cells (P250), in parallel with wild-type MHV (WT-MHV). Compared to MHV-ExoN(-) P3, MHV-ExoN(-) P250 demonstrated enhanced replication and increased competitive fitness without reversion at the ExoN(-) active site. Furthermore, MHV-ExoN(-) P250 was less susceptible than MHV-ExoN(-) P3 to multiple nucleoside analogues, suggesting that MHV-ExoN(-) was under selection for increased replication fidelity. We subsequently identified novel amino acid changes within the RNA-dependent RNA polymerase and nsp14 of MHV-ExoN(-) P250 that partially accounted for the reduced susceptibility to nucleoside analogues. Our results suggest that increased replication fidelity is selected in ExoN(-) CoVs and that there may be a significant barrier to ExoN(-) reversion. These results also support the hypothesis that high-fidelity replication is linked to CoV fitness and indicate that multiple replicase proteins could compensate for ExoN functions during replication.IMPORTANCE Uniquely among RNA viruses, CoVs encode a proofreading exoribonuclease (ExoN) in nsp14 that mediates high-fidelity RNA genome replication. Proofreading-deficient CoVs with disrupted ExoN activity [ExoN(-)] either are nonviable or have significant defects in replication, RNA synthesis, fidelity, fitness, and virulence. In this study, we showed that ExoN(-) murine hepatitis virus can adapt during long-term passage for increased replication and fitness without reverting the ExoN-inactivating mutations. Passage-adapted ExoN(-) mutants also demonstrate increasing resistance to nucleoside analogues that is explained only partially by secondary mutations in nsp12 and nsp14. These data suggest that enhanced resistance to nucleoside analogues is mediated by the interplay of multiple replicase proteins and support the proposed link between CoV fidelity and fitness.
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Affiliation(s)
- Kevin W Graepel
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Xiaotao Lu
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - James Brett Case
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Nicole R Sexton
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Everett Clinton Smith
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Biology, the University of the South, Sewanee, Tennessee, USA
| | - Mark R Denison
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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Abstract
Influenza A virus (IAV) continues to pose an enormous and unpredictable global public health threat, largely due to the continual evolution of escape from preexisting immunity and the potential for zoonotic emergence. Understanding how the unique genetic makeup and structure of IAV populations influences their transmission and evolution is essential for developing more-effective vaccines, therapeutics, and surveillance capabilities. Owing to their mutation-prone replicase and unique genome organization, IAV populations exhibit enormous amounts of diversity both in terms of sequence and functional gene content. Here, I review what is currently known about the genetic and genomic diversity present within IAV populations and how this diversity may shape the replicative and evolutionary dynamics of these viruses.
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Arbovirus Adaptation: Roles in Transmission and Emergence. CURRENT CLINICAL MICROBIOLOGY REPORTS 2017. [DOI: 10.1007/s40588-017-0068-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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