1
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Stapleton JT. Human Pegivirus Type 1: A Common Human Virus That Is Beneficial in Immune-Mediated Disease? Front Immunol 2022; 13:887760. [PMID: 35707535 PMCID: PMC9190258 DOI: 10.3389/fimmu.2022.887760] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/03/2022] [Indexed: 12/25/2022] Open
Abstract
Two groups identified a novel human flavivirus in the mid-1990s. One group named the virus hepatitis G virus (HGV) and the other named it GB Virus type C (GBV-C). Sequence analyses found these two isolates to be the same virus, and subsequent studies found that the virus does not cause hepatitis despite sharing genome organization with hepatitis C virus. Although HGV/GBV-C infection is common and may cause persistent infection in humans, the virus does not appear to directly cause any other known disease state. Thus, the virus was renamed “human pegivirus 1” (HPgV-1) for “persistent G” virus. HPgV-1 is found primarily in lymphocytes and not hepatocytes, and several studies found HPgV-1 infection associated with prolonged survival in people living with HIV. Co-infection of human lymphocytes with HPgV-1 and HIV inhibits HIV replication. Although three viral proteins directly inhibit HIV replication in vitro, the major effects of HPgV-1 leading to reduced HIV-related mortality appear to result from a global reduction in immune activation. HPgV-1 specifically interferes with T cell receptor signaling (TCR) by reducing proximal activation of the lymphocyte specific Src kinase LCK. Although TCR signaling is reduced, T cell activation is not abolished and with sufficient stimulus, T cell functions are enabled. Consequently, HPgV-1 is not associated with immune suppression. The HPgV-1 immunomodulatory effects are associated with beneficial outcomes in other diseases including Ebola virus infection and possibly graft-versus-host-disease following stem cell transplantation. Better understanding of HPgV-1 immune escape and mechanisms of inflammation may identify novel therapies for immune-based diseases.
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Affiliation(s)
- Jack T. Stapleton
- Medicine Service, Iowa City Veterans Administration Healthcare, Iowa City, IA, United States
- Departments of Internal Medicine, Microbiology & Immunology, University of Iowa, Iowa City, IA, United States
- *Correspondence: Jack T. Stapleton,
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2
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Samadi M, Salimi V, Haghshenas MR, Miri SM, Mohebbi SR, Ghaemi A. Clinical and molecular aspects of human pegiviruses in the interaction host and infectious agent. Virol J 2022; 19:41. [PMID: 35264187 PMCID: PMC8905790 DOI: 10.1186/s12985-022-01769-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/16/2022] [Indexed: 12/11/2022] Open
Abstract
Background Human pegivirus 1 (HPgV-1) is a Positive-sense single-stranded RNA (+ ssRNA) virus, discovered in 1995 as a Flaviviridae member, and the closest human virus linked to HCV. In comparison to HCV, HPgV-1 seems to be lymphotropic and connected to the viral group that infects T and B lymphocytes. HPgV-1 infection is not persuasively correlated to any known human disease; nevertheless, multiple studies have reported a connection between chronic HPgV-1 infection and improved survival in HPgV-1/HIV co-infected patients with a delayed and favorable impact on HIV infection development. While the process has not been thoroughly clarified, different mechanisms for these observations have been proposed. HPgV-1 is categorized into seven genotypes and various subtypes. Infection with HPgV-1 is relatively common globally. It can be transferred parenterally, sexually, and through vertical ways, and thereby its co-infection with HIV and HCV is common. In most cases, the clearance of HPgV-1 from the body can be achieved by developing E2 antibodies after infection. Main body In this review, we thoroughly discuss the current knowledge and recent advances in understanding distinct epidemiological, molecular, and clinical aspects of HPgV-1. Conclusion Due to the unique characteristics of the HPgV-1, so advanced research on HPgV-1, particularly in light of HIV co-infection and other diseases, should be conducted to explore the essential mechanisms of HIV clearance and other viruses and thereby suggest novel strategies for viral therapy in the future.
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Affiliation(s)
- Mehdi Samadi
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.,Department of Microbiology, Molecular and Cell-Biology Research Center, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Vahid Salimi
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Haghshenas
- Department of Microbiology, Molecular and Cell-Biology Research Center, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Seyed Mohammad Miri
- Department of Virology, Pasteur Institute of Iran, P.O. Box: 1316943551, Tehran, Iran
| | - Seyed Reza Mohebbi
- Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir Ghaemi
- Department of Virology, Pasteur Institute of Iran, P.O. Box: 1316943551, Tehran, Iran.
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3
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Yu Y, Wan Z, Wang JH, Yang X, Zhang C. Review of human pegivirus: Prevalence, transmission, pathogenesis, and clinical implication. Virulence 2022; 13:324-341. [PMID: 35132924 PMCID: PMC8837232 DOI: 10.1080/21505594.2022.2029328] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Human pegivirus (HPgV-1), previously known as GB virus C (GBV-C) or hepatitis G virus (HGV), is a single-stranded positive RNA virus belonging to the genus Pegivirus of the Flaviviridae family. It is transmitted by percutaneous injuries (PIs), contaminated blood and/or blood products, sexual contact, and vertical mother-to-child transmission. It is widely prevalent in general population, especially in high-risk groups. HPgV-1 viremia is typically cleared within the first 1–2 years of infection in most healthy individuals, but may persist for longer periods of time in immunocompromised individuals and/or those co-infected by other viruses. A large body of evidences indicate that HPgV-1 persistent infection has a beneficial clinical effect on many infectious diseases, such as acquired immunodeficiency syndrome (AIDS) and hepatitis C. The beneficial effects seem to be related to a significant reduction of immune activation, and/or the inhabitation of co-infected viruses (e.g. HIV-1). HPgV-1 has a broad cellular tropism for lymphoid and myeloid cells, and preferentially replicates in bone marrow and spleen without cytopathic effect, implying a therapeutic potential. The paper aims to summarize the natural history, prevalence and distribution characteristics, and pathogenesis of HPgV-1, and discuss its association with other human viral diseases, and potential use in therapy as a biovaccine or viral vector.
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Affiliation(s)
- Yaqi Yu
- College of Life Sciences, Henan Normal University, Xinxiang, China.,Shanghai Public Health Clinical Center, Fudan University, Shanghai, China
| | - Zhenzhou Wan
- Medical Laboratory of Taizhou Fourth People's Hospital, Taizhou, China
| | - Jian-Hua Wang
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Xianguang Yang
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Chiyu Zhang
- Shanghai Public Health Clinical Center, Fudan University, Shanghai, China
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4
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Arhab Y, Bulakhov AG, Pestova TV, Hellen CU. Dissemination of Internal Ribosomal Entry Sites (IRES) Between Viruses by Horizontal Gene Transfer. Viruses 2020; 12:v12060612. [PMID: 32512856 PMCID: PMC7354566 DOI: 10.3390/v12060612] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/01/2020] [Accepted: 06/02/2020] [Indexed: 12/19/2022] Open
Abstract
Members of Picornaviridae and of the Hepacivirus, Pegivirus and Pestivirus genera of Flaviviridae all contain an internal ribosomal entry site (IRES) in the 5'-untranslated region (5'UTR) of their genomes. Each class of IRES has a conserved structure and promotes 5'-end-independent initiation of translation by a different mechanism. Picornavirus 5'UTRs, including the IRES, evolve independently of other parts of the genome and can move between genomes, most commonly by intratypic recombination. We review accumulating evidence that IRESs are genetic entities that can also move between members of different genera and even between families. Type IV IRESs, first identified in the Hepacivirus genus, have subsequently been identified in over 25 genera of Picornaviridae, juxtaposed against diverse coding sequences. In several genera, members have either type IV IRES or an IRES of type I, II or III. Similarly, in the genus Pegivirus, members contain either a type IV IRES or an unrelated type; both classes of IRES also occur in members of the genus Hepacivirus. IRESs utilize different mechanisms, have different factor requirements and contain determinants of viral growth, pathogenesis and cell type specificity. Their dissemination between viruses by horizontal gene transfer has unexpectedly emerged as an important facet of viral evolution.
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Chu L, Jin M, Feng C, Wang X, Zhang D. A highly divergent hepacivirus-like flavivirus in domestic ducks. J Gen Virol 2019; 100:1234-1240. [PMID: 31282853 DOI: 10.1099/jgv.0.001298] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Using random amplification and reverse transcription-PCR, a novel RNA virus was detected in sera of domestic ducks. The full genome of the virus was determined for three strains, identifying the first hepacivirus-like flavivirus in birds. The virus, that we tentatively named duck hepacivirus-like virus (DuHV), possesses several unique molecular features, such as possession of the largest hepacivirus-like polyprotein gene and a Pegivirus A-like internal ribosome entry site. Sequence comparisons and phylogenetic and sliding-window analyses indicated that DuHV is most closely related to, but highly divergent from, the known hepaciviruses. DuHV was detected in 69.7 % of 185 serum samples from four duck species and in 31 of 33 flocks from five provinces of China, reflecting a high prevalence in duck populations and a wide geographical distribution. The detection of DuHV in the same flock in November 2018 and April 2019 suggested that persistent infection can be established in the infected ducks.
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Affiliation(s)
- Lili Chu
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
| | - Meiling Jin
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
| | - Chonglun Feng
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
| | - Xiaoyan Wang
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
| | - Dabing Zhang
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
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6
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Bukowska-Ośko I, Perlejewski K, Pawełczyk A, Rydzanicz M, Pollak A, Popiel M, Cortés KC, Paciorek M, Horban A, Dzieciątkowski T, Radkowski M, Laskus T. Human Pegivirus in Patients with Encephalitis of Unclear Etiology, Poland. Emerg Infect Dis 2019; 24:1785-1794. [PMID: 30226156 PMCID: PMC6154136 DOI: 10.3201/eid2410.180161] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Sequence analysis of human pegivirus from 3 patients indicates that the central nervous system constitutes a separate viral compartment from serum. Human pegivirus (HPgV), previously called hepatitis G virus or GB virus C, is a lymphotropic virus with undefined pathology. Because many viruses from the family Flaviviridae, to which HPgV belongs, are neurotropic, we studied whether HPgV could infect the central nervous system. We tested serum and cerebrospinal fluid samples from 96 patients with a diagnosis of encephalitis for a variety of pathogens by molecular methods and serology; we also tested for autoantibodies against neuronal antigens. We found HPgV in serum and cerebrospinal fluid from 3 patients who had encephalitis of unclear origin; that is, all the markers that had been tested were negative. Single-strand confirmation polymorphism and next-generation sequencing analysis revealed differences between the serum and cerebrospinal fluid–derived viral sequences, which is compatible with the presence of a separate HPgV compartment in the central nervous system. It is unclear whether HPgV was directly responsible for encephalitis in these patients.
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7
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Baechlein C, Grundhoff A, Fischer N, Alawi M, Hoeltig D, Waldmann KH, Becher P. Pegivirus Infection in Domestic Pigs, Germany. Emerg Infect Dis 2018; 22:1312-4. [PMID: 27314228 PMCID: PMC4918184 DOI: 10.3201/eid2207.160024] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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8
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In vitro evolution of high-titer, virus-like vesicles containing a single structural protein. Proc Natl Acad Sci U S A 2014; 111:16866-71. [PMID: 25385608 DOI: 10.1073/pnas.1414991111] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Self-propagating, infectious, virus-like vesicles (VLVs) are generated when an alphavirus RNA replicon expresses the vesicular stomatitis virus glycoprotein (VSV G) as the only structural protein. The mechanism that generates these VLVs lacking a capsid protein has remained a mystery for over 20 years. We present evidence that VLVs arise from membrane-enveloped RNA replication factories (spherules) containing VSV G protein that are largely trapped on the cell surface. After extensive passaging, VLVs evolve to grow to high titers through acquisition of multiple point mutations in their nonstructural replicase proteins. We reconstituted these mutations into a plasmid-based system from which high-titer VLVs can be recovered. One of these mutations generates a late domain motif (PTAP) that is critical for high-titer VLV production. We propose a model in which the VLVs have evolved in vitro to exploit a cellular budding pathway that is hijacked by many enveloped viruses, allowing them to bud efficiently from the cell surface. Our results suggest a basic mechanism of propagation that may have been used by primitive RNA viruses lacking capsid proteins. Capsids may have evolved later to allow more efficient packaging of RNA, greater virus stability, and evasion of innate immunity.
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9
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Sibley SD, Lauck M, Bailey AL, Hyeroba D, Tumukunde A, Weny G, Chapman CA, O’Connor DH, Goldberg TL, Friedrich TC. Discovery and characterization of distinct simian pegiviruses in three wild African Old World monkey species. PLoS One 2014; 9:e98569. [PMID: 24918769 PMCID: PMC4053331 DOI: 10.1371/journal.pone.0098569] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 05/05/2014] [Indexed: 01/08/2023] Open
Abstract
Within the Flaviviridae, the recently designated genus Pegivirus has expanded greatly due to new discoveries in bats, horses, and rodents. Here we report the discovery and characterization of three simian pegiviruses (SPgV) that resemble human pegivirus (HPgV) and infect red colobus monkeys (Procolobus tephrosceles), red-tailed guenons (Cercopithecus ascanius) and an olive baboon (Papio anubis). We have designated these viruses SPgVkrc, SPgVkrtg and SPgVkbab, reflecting their host species' common names, which include reference to their location of origin in Kibale National Park, Uganda. SPgVkrc and SPgVkrtg were detected in 47% (28/60) of red colobus and 42% (5/12) red-tailed guenons, respectively, while SPgVkbab infection was observed in 1 of 23 olive baboons tested. Infections were not associated with any apparent disease, despite the generally high viral loads observed for each variant. These viruses were monophyletic and equally divergent from HPgV and pegiviruses previously identified in chimpanzees (SPgVcpz). Overall, the high degree of conservation of genetic features among the novel SPgVs, HPgV and SPgVcpz suggests conservation of function among these closely related viruses. Our study describes the first primate pegiviruses detected in Old World monkeys, expanding the known genetic diversity and host range of pegiviruses and providing insight into the natural history of this genus.
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Affiliation(s)
- Samuel D. Sibley
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Michael Lauck
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Adam L. Bailey
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | | | | | | | - Colin A. Chapman
- Makerere University, Kampala, Uganda
- Department of Anthropology and McGill School of Environment, Montreal, Quebec, Canada
| | - David H. O’Connor
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Wisconsin National Primate Research Center, Madison, Wisconsin, United States of America
| | - Tony L. Goldberg
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Makerere University, Kampala, Uganda
- Wisconsin National Primate Research Center, Madison, Wisconsin, United States of America
| | - Thomas C. Friedrich
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Wisconsin National Primate Research Center, Madison, Wisconsin, United States of America
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10
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Ghai RR, Sibley SD, Lauck M, Dinis JM, Bailey AL, Chapman CA, Omeja P, Friedrich TC, O'Connor DH, Goldberg TL. Deep sequencing identifies two genotypes and high viral genetic diversity of human pegivirus (GB virus C) in rural Ugandan patients. J Gen Virol 2013; 94:2670-2678. [PMID: 24077364 DOI: 10.1099/vir.0.055509-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Human pegivirus (HPgV), formerly 'GB virus C' or 'hepatitis G virus', is a member of the genus Flavivirus (Flaviviridae) that has garnered significant attention due to its inhibition of HIV, including slowing disease progression and prolonging survival in HIV-infected patients. Currently, there are six proposed HPgV genotypes that have roughly distinct geographical distributions. Genotypes 2 and 3 are the most comprehensively characterized, whereas those genotypes occurring on the African continent, where HPgV prevalence is highest, are less well studied. Using deep sequencing methods, we identified complete coding HPgV sequences in four of 28 patients (14.3%) in rural Uganda, east Africa. One of these sequences corresponds to genotype 1 and is the first complete genome of this genotype from east Africa. The remaining three sequences correspond to genotype 5, a genotype that was previously considered exclusively South African. All four positive samples were collected within a geographical area of less than 25 km(2), showing that multiple HPgV genotypes co-circulate in this area. Analysis of intra-host viral genetic diversity revealed that total single-nucleotide polymorphism frequency was approximately tenfold lower in HPgV than in hepatitis C virus. Finally, one patient was co-infected with HPgV and HIV, which, in combination with the high prevalence of HIV, suggests that this region would be a useful locale to study the interactions and co-evolution of these viruses.
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Affiliation(s)
- Ria R Ghai
- Department of Biology, McGill University, Montreal, QC, Canada
| | - Samuel D Sibley
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Michael Lauck
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Jorge M Dinis
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Adam L Bailey
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Colin A Chapman
- Department of Anthropology and McGill School of Environment, Montreal, QC, Canada, and Wildlife Conservation Society, NY, USA
| | - Patrick Omeja
- Makerere University Biological Field Station, Fort Portal, Uganda
| | - Thomas C Friedrich
- Wisconsin National Primate Research Center, Madison, WI, USA
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - David H O'Connor
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI, USA
| | - Tony L Goldberg
- Wisconsin National Primate Research Center, Madison, WI, USA
- Makerere University Biological Field Station, Fort Portal, Uganda
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
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11
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Abstract
The recent identification of nonprimate hepaciviruses in dogs and then in horses prompted us to look for pegiviruses (GB virus-like viruses) in these species. Although none were detected in canines, we found widespread natural infection of horses by a novel pegivirus. Unique genomic features and phylogenetic analyses confirmed that the tentatively named equine pegivirus (EPgV) represents a novel species within the Pegivirus genus. We also determined that EPgV causes persistent viremia whereas its clinical significance is undetermined.
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12
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Abstract
Hepatitis C virus (HCV) and human pegivirus (HPgV or GB virus C) are globally distributed and infect 2 to 5% of the human population. The lack of tractable-animal models for these viruses, in particular for HCV, has hampered the study of infection, transmission, virulence, immunity, and pathogenesis. To address this challenge, we searched for homologous viruses in small mammals, including wild rodents. Here we report the discovery of several new hepaciviruses (HCV-like viruses) and pegiviruses (GB virus-like viruses) that infect wild rodents. Complete genome sequences were acquired for a rodent hepacivirus (RHV) found in Peromyscus maniculatus and a rodent pegivirus (RPgV) found in Neotoma albigula. Unique genomic features and phylogenetic analyses confirmed that these RHV and RPgV variants represent several novel virus species in the Hepacivirus and Pegivirus genera within the family Flaviviridae. The genetic diversity of the rodent hepaciviruses exceeded that observed for hepaciviruses infecting either humans or non-primates, leading to new insights into the origin, evolution, and host range of hepaciviruses. The presence of genes, encoded proteins, and translation elements homologous to those found in human hepaciviruses and pegiviruses suggests the potential for the development of new animal systems with which to model HCV pathogenesis, vaccine design, and treatment. The genetic and biological characterization of animal homologs of human viruses provides insights into the origins of human infections and enhances our ability to study their pathogenesis and explore preventive and therapeutic interventions. Horses are the only reported host of nonprimate homologs of hepatitis C virus (HCV). Here, we report the discovery of HCV-like viruses in wild rodents. The majority of HCV-like viruses were found in deer mice (Peromyscus maniculatus), a small rodent used in laboratories to study viruses, including hantaviruses. We also identified pegiviruses in rodents that are distinct from the pegiviruses found in primates, bats, and horses. These novel viruses may enable the development of small-animal models for HCV, the most common infectious cause of liver failure and hepatocellular carcinoma after hepatitis B virus, and help to explore the health relevance of the highly prevalent human pegiviruses.
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13
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Timmons CL, Shao Q, Wang C, Liu L, Liu H, Dong X, Liu B. GB virus type C E2 protein inhibits human immunodeficiency virus type 1 assembly through interference with HIV-1 gag plasma membrane targeting. J Infect Dis 2013; 207:1171-80. [PMID: 23303812 PMCID: PMC3583272 DOI: 10.1093/infdis/jit001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Accepted: 10/31/2012] [Indexed: 02/02/2023] Open
Abstract
GB virus type C (GBV-C) is a single-stranded positive-sense RNA virus classified in the Flaviviridae family. Persistent coinfection with GBV-C is associated with lower human immunodeficiency virus type 1 (HIV-1) load, higher CD4(+) T-cell count, and prolonged survival in HIV-1 coinfected patients. The GBV-C envelope glycoprotein E2 has been reported to interfere with HIV-1 entry. In this study, we showed that the expression of GBV-C E2 inhibited HIV-1 Gag assembly and release. Expression of glycosylated GBV-C E2 inhibited HIV-1 Gag precursor processing, resulting in lower production of CAp24 and MAp17, while the overall expression level of the Gag precursor Pr55 remained unchanged. Membrane floatation gradient and indirect immunofluorescence confocal microscopy analysis showed that glycosylated E2 disrupted HIV-1 Gag trafficking to the plasma membrane, resulting in Gag accumulation in subcellular compartments. This interference in HIV-1 Gag trafficking led to diminished HIV-1 particle production, which is a critical step for HIV-1 to infect new host cells. These findings shed light on a novel mechanism used by GBV-C E2 to inhibit HIV-1 replication and may provide insight into new approaches for suppressing HIV-1 replication.
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Affiliation(s)
- Christine L. Timmons
- Center for AIDS Health Disparities Research
- Department of Microbiology and Immunology, Meharry Medical College, Nashville, Tennessee
| | | | - Chenliang Wang
- Center for AIDS Health Disparities Research
- Institute of Gastroenterology and Institute of Human Virology, Sun Yat-sen University, Guangzhou, Guangdong, Peoples of Republic of China
| | - Ling Liu
- Center for AIDS Health Disparities Research
| | - Huanliang Liu
- Institute of Gastroenterology and Institute of Human Virology, Sun Yat-sen University, Guangzhou, Guangdong, Peoples of Republic of China
| | - Xinhong Dong
- Center for AIDS Health Disparities Research
- Department of Microbiology and Immunology, Meharry Medical College, Nashville, Tennessee
| | - Bindong Liu
- Center for AIDS Health Disparities Research
- Department of Microbiology and Immunology, Meharry Medical College, Nashville, Tennessee
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14
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Neibecker M, Schwarze-Zander C, Rockstroh JK, Spengler U, Blackard JT. Evidence for extensive genotypic diversity and recombination of GB virus C (GBV-C) in Germany. J Med Virol 2011; 83:685-94. [PMID: 21328384 DOI: 10.1002/jmv.22029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Multiple genotypes of GB virus C (GBV-C)-a non-pathogenic flavivirus-have been identified to date, although they are not uniformly distributed worldwide. It has also been suggested that GBV-C genotype may play a role in modulating HIV disease; however, the prevalence and genotype distribution of GBV-C has not been adequately studied in most countries. Among 408 HIV positive subjects in Germany, 97 (23.8%) had detectable GBV-C RNA. Based on sequencing of the 5' untranslated region (5'-UTR), the GBV-C genotypes were 1 (n=8; 8.2%), 2 (n=81; 83.5%), and 3 (n=2; 2.1%), as well as a unique genotype not previously reported (n=6; 6.2%). Among 17 samples also sequenced in the envelope 2 (E2) region, 14 had concordant genotype results when comparing the 5'-UTR and E2, while evidence of intergenotypic recombination was observed among E2 sequences from 3 individuals. These results suggest that genotypic diversity and viral recombination contribute to the overall genetic variability of GBV-C.
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Affiliation(s)
- Markus Neibecker
- Department of Internal Medicine I, University Hospital Bonn, Bonn, Germany
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15
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Stapleton JT, Foung S, Muerhoff AS, Bukh J, Simmonds P. The GB viruses: a review and proposed classification of GBV-A, GBV-C (HGV), and GBV-D in genus Pegivirus within the family Flaviviridae. J Gen Virol 2010; 92:233-46. [PMID: 21084497 PMCID: PMC3081076 DOI: 10.1099/vir.0.027490-0] [Citation(s) in RCA: 212] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In 1967, it was reported that experimental inoculation of serum from a surgeon (G.B.) with acute hepatitis into tamarins resulted in hepatitis. In 1995, two new members of the family Flaviviridae, named GBV-A and GBV-B, were identified in tamarins that developed hepatitis following inoculation with the 11th GB passage. Neither virus infects humans, and a number of GBV-A variants were identified in wild New World monkeys that were captured. Subsequently, a related human virus was identified [named GBV-C or hepatitis G virus (HGV)], and recently a more distantly related virus (named GBV-D) was discovered in bats. Only GBV-B, a second species within the genus Hepacivirus (type species hepatitis C virus), has been shown to cause hepatitis; it causes acute hepatitis in experimentally infected tamarins. The other GB viruses have however not been assigned to a genus within the family Flaviviridae. Based on phylogenetic relationships, genome organization and pathogenic features of the GB viruses, we propose to classify GBV-A-like viruses, GBV-C and GBV-D as members of a fourth genus in the family Flaviviridae, named Pegivirus (pe, persistent; g, GB or G). We also propose renaming 'GB' viruses within the tentative genus Pegivirus to reflect their host origin.
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Affiliation(s)
- Jack T Stapleton
- Department of Internal Medicine, Veterans Administration Medical Center and the University of Iowa, Iowa City, IA, USA.
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Abstract
GB virus C/hepatitis G virus (GBV-C/HGV) is the most closely related human virus to hepatitis C virus (HCV). GBV-C is lymphotropic and not associated with any known disease, although it is associated with improved survival in HIV-infected individuals. In peripheral blood mononuclear cells, GBV-C induces the release of soluble ligands for HIV entry receptors (RANTES, MIP-1a, MIP-1b and SDF-1), suggesting that GBV-C may interact with lymphocytes to induce a chemokine and/or cytokine milieu that is inhibitory to HIV infection. Expression of GBV-C envelope glycoprotein E2 in CD4+ T cells or addition of recombinant E2 to CD4 cells recapitulates the HIV inhibition seen with GBV-C infection. Like HCV E2, GBV-C E2 is predicted to be post-translationally processed in the endoplasmic reticulum and is involved with cell binding. The C-termini of GBV-C E1 and E2 proteins contain predicted transmembrane domains sharing features with HCV TM domains. To date, cellular receptor(s) for GBV-C E2 have not been identified. GBV-C E2-mediated HIV inhibition is dose-dependent and HIV replication is blocked at the binding and/or entry step. In addition, a putative GBV-C E2 fusion peptide interferes with HIV gp41 peptide oligomerization required for HIV-1 fusion, further suggesting that GBV-C E2 may inhibit HIV entry. Additional work is needed to identify the GBV-C E2 cellular receptor, characterize GBV-C E2 domains responsible for HIV inhibition, and to examine GBV-C E2-mediated fusion in the context of the entire envelope protein or viral-particles. Understanding the mechanisms of action may identify novel approaches to HIV therapy.
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Affiliation(s)
- Emma L. Mohr
- Department of Internal Medicine and the Interdisciplinary Program on Molecular and Cellular Biology, The University of Iowa
| | - Jack T. Stapleton
- Department of Internal Medicine and the Interdisciplinary Program on Molecular and Cellular Biology, The University of Iowa,The Iowa City VA Medical Center, Iowa City, IA, USA
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McLinden JH, Kaufman TM, Xiang J, Chang Q, Klinzman D, Engel AM, Hess G, Schmidt U, Houghton M, Stapleton JT. Characterization of an immunodominant antigenic site on GB virus C glycoprotein E2 that is involved in cell binding. J Virol 2006; 80:12131-40. [PMID: 17035329 PMCID: PMC1676310 DOI: 10.1128/jvi.01206-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
GB virus type C (GBV-C) is a human flavivirus that may cause persistent infection, although most infected individuals clear viremia and develop antibodies to the envelope glycoprotein E2. To study GBV-C E2 antigenicity and cell binding, murine anti-E2 monoclonal antibodies (MAbs) were evaluated to topologically map immunogenic sites on GBV-C E2 and for the ability to detect or block recombinant E2 binding to various cell lines. Five competition groups of MAbs were identified. Groups I and II did not compete with each other. Group III competed with both groups I and II. Group IV did not compete with group I, II, or III. One MAb competed with all of the other MAbs, suggesting that the epitopes bound by these MAbs are intimately related. Individually, none of the MAbs competed extensively with polyclonal human convalescent antibody (PcAb); however, combinations of all five MAb groups completely blocked PcAb binding to E2, suggesting that the epitopes bound by these MAbs form a single, immunodominant antigenic site. Only group I and III MAbs detected purified recombinant E2 bound to cells in binding assays. In contrast, group II MAbs neutralized the binding of E2 to cells. Both PcAb and MAbs were conformation dependent, with the exception of one group II MAb (M6). M6 bound to a five-amino-acid sequence on E2 if the peptide included four C-terminal or eight N-terminal residues, suggesting that the GBV-C E2 protein contains a single immunodominant antigenic site which includes a complex epitope that is involved in specific cellular binding.
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Affiliation(s)
- James H McLinden
- Department of Internal Medicine, SW54, GH, The University of Iowa, Iowa City, IA 52242, USA
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Xiang J, McLinden JH, Chang Q, Kaufman TM, Stapleton JT. An 85-aa segment of the GB virus type C NS5A phosphoprotein inhibits HIV-1 replication in CD4+ Jurkat T cells. Proc Natl Acad Sci U S A 2006; 103:15570-5. [PMID: 17030806 PMCID: PMC1622863 DOI: 10.1073/pnas.0604728103] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
GB virus type C (GBV-C) is an apparently nonpathogenic virus that replicates in T and B lymphocytes and is a common cause of persistent human infection. Among HIV-1-infected individuals, persistent coinfection with GBV-C is associated with prolonged survival, and infection of blood mononuclear cells or CD4+ T cells with GBV-C and HIV in vitro results in significantly reduced HIV-1 replication. To date, the viral protein(s) that lead to HIV inhibition have not been identified. The GBV-C nonstructural phosphoprotein (NS5A) is predicted to have pleotropic effects on cells, including interactions with the IFN-induced dsRNA-activated protein kinase (PKR). We studied GBV-C NS5A to determine whether it is involved in inhibition of HIV replication. GBV-C NS5A protein from an isolate that was cleared by IFN therapy did not inhibit PKR, whereas NS5A from an isolate that was not cleared by IFN-inhibited PKR function in a yeast genetic system. Both of these GBV-C NS5A proteins were expressed in a CD4+ T cell line (Jurkat), and both induced a potent, dose-dependent inhibition of HIV-1 replication, thus the effect was independent of PKR inhibition. NS5A induced the release of the chemokine SDF-1 and decreased surface expression of the HIV coreceptor CXCR4, potentially explaining the HIV inhibition. Deletion mapping of the NS5A protein found that an 85-aa region between amino acids 152 and 237 inhibits HIV-1 replication. Thus, GBV-C NS5A protein alters the cellular milieu necessary for HIV-1 replication and may provide a previously undescribed therapeutic approach for anti-HIV therapy.
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Affiliation(s)
- Jinhua Xiang
- Research Service and Department of Internal Medicine, Iowa City Veterans Affairs Medical Center and University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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Souza IE, Zhang W, Diaz RS, Chaloner K, Klinzman D, Stapleton JT. Effect of GB virus C on response to antiretroviral therapy in HIV-infected Brazilians. HIV Med 2006; 7:25-31. [PMID: 16313289 DOI: 10.1111/j.1468-1293.2005.00339.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVES GB virus C (GBV-C) infection is associated with delayed mortality in HIV-infected people in most, but not all, studies. Previous investigations of the effect of GBV-C viraemia on response to antiretroviral therapy (ART) were inconclusive. To determine the effect of GBV-C on ART, we retrospectively analysed plasma samples taken from patients in a prospective randomized clinical trial of ART in HIV-positive Brazilians. METHODS GBV-C viraemia was characterized by testing stored serum samples from 175 participants by reverse transcriptase-polymerase chain reaction (RT-PCR). Subjects were randomized to receive indinavir (n=59), zidovudine and lamivudine (n=58), or zidovudine, lamivudine and indinavir (n=58). The effect of GBV-C viraemia on the average change in HIV viral load and CD4 count following initiation of therapy was evaluated in a multiple regression analysis. RESULTS The prevalence of GBV-C viraemia was similar to that observed in previous studies (24%). HIV viral load decreased following ART to a significantly greater extent in patients with GBV-C viraemia (by 0.48 log(10) HIV-1 RNA copies/mL, P=0.009, adjusting for age, ART group, and baseline CD4 count). Although there was no significant difference in change in CD4 count between individuals with and without GBV-C viraemia overall, CD4 counts were higher following 48 weeks of therapy in GBV-C viraemic individuals receiving the least potent ART regimen (zidovudine and lamivudine) compared with those without GBV-C infection. CONCLUSIONS GBV-C viraemia is associated with an enhanced reduction of HIV viral load in response to ART. In this study of treatment-naive individuals during 48 weeks of follow up, patients with GBV-C viraemia had reductions in HIV viral load that were approximately 0.5 log copies/mL greater than those found in patients without GBV-C viraemia. This is similar to reductions observed with nucleoside reverse transcriptase inhibitors.
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Affiliation(s)
- I E Souza
- Department of Internal Medicine, University of Iowa Roy, Iowa City, IA 52242, USA
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21
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Pisarev AV, Shirokikh NE, Hellen CUT. Translation initiation by factor-independent binding of eukaryotic ribosomes to internal ribosomal entry sites. C R Biol 2005; 328:589-605. [PMID: 15992743 DOI: 10.1016/j.crvi.2005.02.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Accepted: 02/16/2005] [Indexed: 02/05/2023]
Abstract
Two exceptional mechanisms of eukaryotic translation initiation have recently been identified that differ fundamentally from the canonical factor-mediated, end-dependent mechanism of ribosomal attachment to mRNA. Instead, ribosomal 40S subunits bind in a factor-independent manner to the internal ribosomal entry site (IRES) in an mRNA. These two mechanisms are exemplified by initiation on the unrelated approximately 300 nt.-long Hepatitis C virus (HCV) IRES and the approximately 200 nt.-long cricket paralysis virus (CrPV) intergenic region (IGR) IRES, respectively. Ribosomal binding involves interaction with multiple non-contiguous sites on these IRESs, and therefore also differs from the factor-independent attachment of prokaryotic ribosomes to mRNA, which involves base-pairing to the linear Shine-Dalgarno sequence. The HCV IRES binds to the solvent side of the 40S subunit, docks a domain of the IRES into the ribosomal exit (E) site and places the initiation codon in the ribosomal peptidyl (P) site. Subsequent binding of eIF3 and the eIF2-GTP/initiator tRNA complex to form a 48S complex is followed by subunit joining to form an 80S ribosome. The CrPV IRES binds to ribosomes in a very different manner, by occupying the ribosomal E and P sites in the intersubunit cavity, thereby excluding initiator tRNA. Ribosomes enter the elongation stage of translation directly, without any involvement of initiator tRNA or initiation factors, following recruitment of aminoacyl-tRNA to the ribosomal aminoacyl (A) site and translocation of it to the P site.
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Affiliation(s)
- Andrey V Pisarev
- Department of Microbiology and Immunology, State University of New York, SUNY, 450 Clarkson Ave., Brooklyn, NY 11203, USA
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Arden KE, Nissen MD, Sloots TP, Mackay IM. New human coronavirus, HCoV-NL63, associated with severe lower respiratory tract disease in Australia. J Med Virol 2005; 75:455-62. [PMID: 15648064 PMCID: PMC7166768 DOI: 10.1002/jmv.20288] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
A new human coronavirus, HCoV‐NL63, was associated recently with bronchiolitis. The current study aimed to examine retrospectively stored specimens for the presence of HCoV‐NL63 using nested RT‐PCR assays targeting the 1a and 1b genes. The study population was composed of patients with acute respiratory disease warranting presentation to Queensland hospitals. HCoV‐NL63 was detected in the nasopharyngeal aspirates (NPA) of 16 of 840 specimens representing 766 patients (2%). HCoV‐NL63 positive individuals were diagnosed most commonly with lower respiratory tract (LRT) disease (81%). The clinical diagnosis was commonly supported by an abnormal chest X‐ray (56%) together with respiratory distress (50%), wheeze (44%), and râles (25%) on first presentation with HCoV‐NL63 infection. All patients positive for HCoV‐NL63 required admission to hospital. Among 38% of HCoV‐NL63 positive specimens a second pathogen was detected. Sequencing of amplicon from gene 1b revealed more than 99% nucleotide homology with the viral type strains while sequencing amplicon from gene 1a permitted the grouping of viral strains. It was shown that HCoV‐NL63 is associated with severe LRT disease in an Australian hospital setting during the cooler months of the year. We propose that HCoV‐NL63 is a global and seasonal pathogen of both children and adults associated with severe LRT illness. J. Med. Virol. 75:455–462, 2005. © 2005 Wiley‐Liss, Inc.
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Affiliation(s)
- Katherine E. Arden
- Clinical Virology and Molecular Microbiology Research Units, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Queensland, Australia
- Clinical and Medical Virology Centre, University of Queensland, Queensland, Australia
| | - Michael D. Nissen
- Clinical Virology and Molecular Microbiology Research Units, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Queensland, Australia
- Clinical and Medical Virology Centre, University of Queensland, Queensland, Australia
- Division of Microbiology, Queensland Health Pathology Service, Royal Brisbane Hospitals Campus, Queensland, Australia
- Department of Paediatrics and Child Health, Royal Children's Hospitals, Queensland, Australia
| | - Theo P. Sloots
- Clinical Virology and Molecular Microbiology Research Units, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Queensland, Australia
- Clinical and Medical Virology Centre, University of Queensland, Queensland, Australia
- Division of Microbiology, Queensland Health Pathology Service, Royal Brisbane Hospitals Campus, Queensland, Australia
- Department of Paediatrics and Child Health, Royal Children's Hospitals, Queensland, Australia
| | - Ian M. Mackay
- Clinical Virology and Molecular Microbiology Research Units, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Queensland, Australia
- Clinical and Medical Virology Centre, University of Queensland, Queensland, Australia
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Muerhoff AS, Leary TP, Sathar MA, Dawson GJ, Desai SM. African origin of GB virus C determined by phylogenetic analysis of a complete genotype 5 genome from South Africa. J Gen Virol 2005; 86:1729-1735. [PMID: 15914851 DOI: 10.1099/vir.0.80854-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
GB virus C (GBV-C), a positive-strand RNA virus, currently infects approximately one-sixth of the world's population. This virus exists as a collection of genotypes whose global distribution correlates with geographical origin. Genotyping of GBV-C isolates by phylogenetic analysis has relied upon the use of 5'-untranslated region (5'-UTR) sequences, however, complete genome sequences are used to demonstrate definitively their existence and geographical correlation. Initial identification of the fifth genotype from South Africa was based upon phylogenetic analysis of the 5'-UTR. It was sought to confirm this classification by analysis of full-length E2 genes from South African isolates and by analysis of a complete genotype 5 genome. Analysis of full-length E2 genes from 28 GBV-C-infected South African individuals revealed the existence of a unique group of 18 isolates, distinct from the other four genotypes. Bootstrap analysis provided strong support (95 %) for this fifth group. The remaining isolates were either genotype 1 (n=8) or 2 (n=2). Analysis of human E2 gene sequences, with the E2 gene from the chimpanzee variant GBV-Ctro included as the outgroup, produced a tree rooted on the genotype 1 branch. The complete genome nucleotide sequence of South African genotype 5 isolate D50 was determined. Phylogenetic analysis of the 5'-UTR and open reading frame produced congruent trees that grouped the sequences into five major genotypes. Inclusion of the corresponding region of the chimpanzee isolate GBV-Ctro in the analysis produced trees rooted on the branch leading to the genotype 5 isolate D50, suggesting an ancient African origin of GBV-C.
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Affiliation(s)
- A Scott Muerhoff
- Infectious Diseases Research and Development, Abbott Diagnostics Division, Abbott Laboratories, Dept 9NB, Bldg AP20-4, 100 Abbott Park Road, Abbott Park, IL 60064-6015, USA
| | - Thomas P Leary
- Infectious Diseases Research and Development, Abbott Diagnostics Division, Abbott Laboratories, Dept 9NB, Bldg AP20-4, 100 Abbott Park Road, Abbott Park, IL 60064-6015, USA
| | - Mahomed A Sathar
- Infectious Disease Unit, Nelson R. Mandela School of Medicine, Doris Duke Research Institute, University of KwaZulu-Natal, South Africa
| | - George J Dawson
- Infectious Diseases Research and Development, Abbott Diagnostics Division, Abbott Laboratories, Dept 9NB, Bldg AP20-4, 100 Abbott Park Road, Abbott Park, IL 60064-6015, USA
| | - Suresh M Desai
- Infectious Diseases Research and Development, Abbott Diagnostics Division, Abbott Laboratories, Dept 9NB, Bldg AP20-4, 100 Abbott Park Road, Abbott Park, IL 60064-6015, USA
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Thurner C, Witwer C, Hofacker IL, Stadler PF. Conserved RNA secondary structures in Flaviviridae genomes. J Gen Virol 2004; 85:1113-1124. [PMID: 15105528 DOI: 10.1099/vir.0.19462-0] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Presented here is a comprehensive computational survey of evolutionarily conserved secondary structure motifs in the genomic RNAs of the family Flaviviridae: This virus family consists of the three genera Flavivirus, Pestivirus and Hepacivirus and the group of GB virus C/hepatitis G virus with a currently uncertain taxonomic classification. Based on the control of replication and translation, two subgroups were considered separately: the genus Flavivirus, with its type I cap structure at the 5' untranslated region (UTR) and a highly structured 3' UTR, and the remaining three groups, which exhibit translation control by means of an internal ribosomal entry site (IRES) in the 5' UTR and a much shorter less-structured 3' UTR. The main findings of this survey are strong hints for the possibility of genome cyclization in hepatitis C virus and GB virus C/hepatitis G virus in addition to the flaviviruses; a surprisingly large number of conserved RNA motifs in the coding regions; and a lower level of detailed structural conservation in the IRES and 3' UTR motifs than reported in the literature. An electronic atlas organizes the information on the more than 150 conserved, and therefore putatively functional, RNA secondary structure elements.
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Affiliation(s)
- Caroline Thurner
- Institut für Theoretische Chemie und Molekulare Strukturbiologie, Universität Wien, Währingerstraße 17, A-1090 Wien, Austria
| | - Christina Witwer
- Institut für Theoretische Chemie und Molekulare Strukturbiologie, Universität Wien, Währingerstraße 17, A-1090 Wien, Austria
| | - Ivo L Hofacker
- Institut für Theoretische Chemie und Molekulare Strukturbiologie, Universität Wien, Währingerstraße 17, A-1090 Wien, Austria
| | - Peter F Stadler
- The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA
- Bioinformatik, Institut für Informatik, Universität Leipzig, Kreuzstraße 7b, D-04103 Leipzig, Germany
- Institut für Theoretische Chemie und Molekulare Strukturbiologie, Universität Wien, Währingerstraße 17, A-1090 Wien, Austria
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George SL, Xiang J, Stapleton JT. Clinical isolates of GB virus type C vary in their ability to persist and replicate in peripheral blood mononuclear cell cultures. Virology 2004; 316:191-201. [PMID: 14644602 DOI: 10.1016/s0042-6822(03)00585-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
GB virus C/hepatitis G virus (GBV-C) replication in vitro is inefficient and inconsistent. In this study, clinical isolates of GBV-C were evaluated using peripheral blood mononuclear cell (PBMC) based culture methods. Isolates varied consistently in their ability to persistently replicate, and yield increased in cells grown without PHA/IL-2 stimulation. The deduced polyprotein sequence of an isolate that replicated well was determined (GenBank AY196904) and compared to 20 full-length GBV-C sequences. Fourteen of the 16 unique amino acid polymorphisms identified were in the coding regions for nonstructural proteins associated with interferon resistance and RNA replication. These data indicate that clinical GBV-C isolates vary in their ability to persist in culture, do not require PHA/IL-2 stimulation, and that sequence variability in key regulatory regions may affect growth in PBMC cultures. Since GBV-C appears to inhibit HIV replication in a coinfection model, these studies should facilitate determination of the mechanism of this interaction.
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Affiliation(s)
- Sarah L George
- Departments of Internal Medicine and Research, Iowa City VA Medical Center, University of Iowa, and the Helen C. Levitt Center for Viral Pathogenesis, Iowa City, IA 52242, USA
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Takács M, Szomor KN, Szendroi A, Dencs A, Brojnás J, Rusvai E, Berencsi G. Prevalence of GB virus C/hepatitis G virus in Hungary. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 2002; 34:283-7. [PMID: 12443828 DOI: 10.1111/j.1574-695x.2002.tb00635.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In 1995 a new flavivirus, GB virus C/hepatitis G virus (GBV-C/HGV), was discovered. The aim of this study was to determine the prevalence of the virus in healthy persons and hepatitis patients in Hungary. The sera of 408 healthy persons older than 60 years were tested for the presence of GBV-C/HGV antibodies, and 113 were positive (28%). Eight of the 71 healthy persons younger than 60 years and twenty of the 51 sera (39%) taken from patients suffering from hepatitis of unknown origin proved to be positive for GBV-C/HGV antibodies. Ten of the 124 sera (8%) of healthy persons and 36 of the 247 sera (14.6%) of hepatitis patients proved to be positive for GBV-C/HGV RNA. Eleven PCR products were sequenced, and the sequences were found to be different from each other and from the previously published ones. However, three sequences taken from the same patient at different times were identical. These results show that GBV-C/HGV is present in Hungary and cannot be considered rare.
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Affiliation(s)
- Mária Takács
- Division of Virology, 'Béla Johan' National Center for Epidemiology, H-1097, Gyáli út 2-6, Budapest, Hungary.
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Cuceanu NM, Tuplin A, Simmonds P. Evolutionarily conserved RNA secondary structures in coding and non-coding sequences at the 3' end of the hepatitis G virus/GB-virus C genome. J Gen Virol 2001; 82:713-722. [PMID: 11257175 DOI: 10.1099/0022-1317-82-4-713] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hepatitis G virus (HGV)/GB virus C (GBV-C) causes persistent, non-pathogenic infection in a large proportion of the human population. Epidemiological and genetic evidence indicates a long-term association between HGV/GBV-C and related viruses and a range of primate species, and the co-speciation of these viruses with their hosts during primate evolution. Using a combination of covariance scanning and analysis of variability at synonymous sites, we previously demonstrated that the coding regions of HGV/GBV-C may contain extensive secondary structure of undefined function (Simmonds & Smith, Journal of Virology 73, 5787-5794, 1999 ). In this study we have carried out a detailed comparison of the structure of the 3'untranslated region (3'UTR) of HGV/GBV-C with that of the upstream NS5B coding sequence. By investigation of free energies on folding, secondary structure predictive algorithms and analysis of covariance between HGV/GBV-C genotypes 1-4 and the more distantly related HGV/GBV-C chimpanzee variant, we obtained evidence for extensive RNA secondary structure formation in both regions. In particular, the NS5B region contained long stem-loop structures of up to 38 internally paired nucleotides which were evolutionarily conserved between human and chimpanzee HGV/GBV-C variants. The prediction of similar structures in the same region of hepatitis C virus may allow the functions of these structures to be determined with a more tractable experimental model.
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Affiliation(s)
- N M Cuceanu
- Laboratory for Clinical and Molecular Virology, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK1
| | - A Tuplin
- Laboratory for Clinical and Molecular Virology, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK1
| | - P Simmonds
- Laboratory for Clinical and Molecular Virology, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK1
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Sathar M, Soni P, York D. GB virus C/hepatitis G virus (GBV-C/HGV): still looking for a disease. Int J Exp Pathol 2001. [PMID: 11168678 DOI: 10.1046/j.1365-2613.2000.00166.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
GB Virus C and Hepatitis G Virus (GBV-C/HGV) are positive, single-stranded flaviviruses. GBV-C and HGV are independent isolates of the same virus. Transmission via the blood-borne route is the commonest mode, although vertical and sexual transmission is well documented. GBV-C/HGV is distributed globally; its prevalence in the general population is 10 fold higher in African countries than in non-African countries. High prevalences of GBV-C/HGV have been found in subjects with frequent parenteral exposure and in groups at high risk of exposure to blood and blood products. The clinical significance of human infection with GBV-C/HGV is currently unclear. The virus can establish both acute and chronic infection and appears to be sensitive to interferon. Only some 12-15% of chronic Non-A, B, C hepatitis cases are infected with GBV-C/HGV. A direct association with liver pathology is still lacking and it is not yet clear as to whether GBV-C/HGV is indeed a hepatotropic virus. Current evidence suggests that the spectrum of association of GBV-C/HGV infection with extrahepatic diseases ranges from haematalogical diseases, aplastic anaemia, human immunodeficiency virus (HIV)-positive idiopathic thrombocytopenia and thalassemia, through to common variable immune deficiency and cryoglobunemia.
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Affiliation(s)
- M Sathar
- Department of Medicine, Nelson R Mandela School of Medicine, University of Natal/King Edward VIII Hospital, Durban, South Africa
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Abstract
AIM: To detect infection rate of GBV-C/HGV in hepatitis C patients, to determine the methods of higher sensitivity and the primers of higher efficiency for GBV-C/HGV RNA detection and to study the dominant subtype and mutation of GBV-C/HGV.
METHODS: Quantitative RT-PCR for detection pf HCV RNA concentration in serum samples, RT-nested PCR with two sets of primers for detection of GBV-CRNA, RT-PCR ELISA with two sets of primers for detection of HGV RNA, nucleotide sequence and putative amino acid sequence analysis.
RESULTS: The positive rates of GBV-C RNA at the 5’-NCR and NS3 region in 211 serums amples from the patients with HCV infection were 31.8% and 22.8% respectively. The positive rates of HGV RNA at the 5’-NCR and NS5 region in the same samples were 47.9% and 31.8% respectively. The total positive rate of GBV-C/HGV RNA was as high as 55.5%. HCV copy numbers in the patients without GBV-C/HGV coinfection were statistically higher than that in the patients with GBV-C/HGV coinfection (P < 0.01). Frequent mutation of nucleotide residue was present in the amplification products. Frameshift mutation was found in two samples with GBV-C NS3 region nucleotide sequences. All nucleotide sequences from amplification products showed higher homology to HGV genome than to GBV-C genome even though part of the sequences were amplified with GBV-C primers.
CONCLUSION: A high frequency of GBV-C/HGV coinfection existed in the hepatitis C patients. RT-PCR ELISA was more sensitive than RT-nested PCR for detection of GBV-C/HGV RNA. The primers derived from the 5’-NCR was more efficient than those derived from the NS3 and NS5 regions. A reverse relationship was found to exist between HCV RNA concentration and GBV-C/HGV infection frequency. HGV was the dominant subtype of the virus in the local area. The major mutations of GBV-C/HGV genomes were random mutation of nucleotide residue.
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Xiang J, Wünschmann S, Schmidt W, Shao J, Stapleton JT. Full-length GB virus C (Hepatitis G virus) RNA transcripts are infectious in primary CD4-positive T cells. J Virol 2000; 74:9125-33. [PMID: 10982359 PMCID: PMC102111 DOI: 10.1128/jvi.74.19.9125-9133.2000] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2000] [Accepted: 06/21/2000] [Indexed: 11/20/2022] Open
Abstract
GB virus C (GBV-C or hepatitis G virus) is a recently described flavivirus which frequently leads to chronic viremia in humans. Although GBV-C is associated with acute posttransfusion hepatitis, it is not clear if the virus is pathogenic for humans. We constructed a full-length cDNA from the plasma of a person with chronic GBV-C viremia. Peripheral blood mononuclear cells (PBMCs) transfected with full-length RNA transcripts from this GBV-C clone resulted in viral replication. This was demonstrated by serial passage of virus from cell culture supernatants, detection of increasing concentrations of positive- and negative-sense GBV-C RNA over time, and the detection of the GBV-C E2 antigen by confocal microscopy. In addition, two types of GBV-C particles were identified in cell lysates; these particles had buoyant densities of 1.06 and 1.12 to 1.17 g/ml in sucrose gradients. PBMCs sorted for expression of CD4 contained 100-fold-more GBV-C RNA than CD4-negative cells. Taken together, these data demonstrate that RNA transcripts from GBV-C full-length cDNA are infectious in primary CD4-positive T cells. In contrast, RNA transcripts from an infectious hepatitis C virus clone did not replicate in the same cell culture system. Infectious RNA transcripts from GBV-C cDNA should prove useful for studying viral replication and may allow identification of differences between GBV-C and hepatitis C virus cultivation in vitro.
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Affiliation(s)
- J Xiang
- Department of Internal Medicine and Research, Iowa City Veterans Administration Medical Center and The University of Iowa College of Medicine, Iowa City, Iowa 52242, USA
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31
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Abstract
GB Virus C and Hepatitis G Virus (GBV-C/HGV) are positive, single-stranded flaviviruses. GBV-C and HGV are independent isolates of the same virus. Transmission via the blood-borne route is the commonest mode, although vertical and sexual transmission is well documented. GBV-C/HGV is distributed globally; its prevalence in the general population is 10 fold higher in African countries than in non-African countries. High prevalences of GBV-C/HGV have been found in subjects with frequent parenteral exposure and in groups at high risk of exposure to blood and blood products. The clinical significance of human infection with GBV-C/HGV is currently unclear. The virus can establish both acute and chronic infection and appears to be sensitive to interferon. Only some 12-15% of chronic Non-A, B, C hepatitis cases are infected with GBV-C/HGV. A direct association with liver pathology is still lacking and it is not yet clear as to whether GBV-C/HGV is indeed a hepatotropic virus. Current evidence suggests that the spectrum of association of GBV-C/HGV infection with extrahepatic diseases ranges from haematalogical diseases, aplastic anaemia, human immunodeficiency virus (HIV)-positive idiopathic thrombocytopenia and thalassemia, through to common variable immune deficiency and cryoglobunemia.
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Affiliation(s)
- M Sathar
- Department of Medicine, Nelson R Mandela School of Medicine, University of Natal/King Edward VIII Hospital, Durban, South Africa
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32
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Shao L, Shinzawa H, Zhang X, Smith DB, Watanabe H, Mitsuhashi H, Saito K, Saito T, Togashi H, Takahashi T. Diversity of hepatitis G virus within a single infected individual. Virus Genes 2000; 21:215-21. [PMID: 11129638 DOI: 10.1023/a:1008195631870] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The extent of population diversity among GB virus C (GBV-C)/hepatitis G virus (HGV) within a persistently infected individual (Iw) was investigated by sequence analysis of multiple clones generated from polymerase chain reaction (PCR)-amplified products of cDNA analogous to fragments of 5' non-coding region (5'NC), envelope region 1/2 (E1/E2) and non-structural region 3 (NS3) of viral genome. Although nucleotide substitutions were more common in coding regions than in the 5'NC region, there was no region corresponding to the hypervariable region of hepatitis C virus in the E1/E2 region. Transition substitution exceeded transversion by 7 to 12-fold, and 79.4% of substitutions were synonymous. This bias against substitutions producing amino acid replacements and the use of Pfu DNA polymerase with an error rate 10 times lower than the observed frequency of substitution, suggests that most substitutions were not artefactual. This data suggests that individual genomes of HGV within an infected individual may differ from each other at 0.23-0.84% nucleotide position and at 0.42-0.61% amino acid position.
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Affiliation(s)
- L Shao
- Second Department of Internal Medicine, Yamagata University School of Medicine, Japan
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33
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Kanda T, Yokosuka O, Kawal S, Imazeki F, Saisho H. Sequence-motif analysis of 5'-untranslated region of GB virus-C in Japanese patients. J Gastroenterol Hepatol 2000; 15:1048-53. [PMID: 11059936 DOI: 10.1046/j.1440-1746.2000.02284.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND GB Virus C (GBV-C) is considered to belong to the Flaviviridae; however, the structures of the N-terminal end of its putative polyprotein are not well known. The internal ribosomal entry site (IRES) at the 5'-untranslated region of GBV-C and an initiating codon at nucleotides (nt) 552-554 have been proposed. We investigated the validity of this proposal. METHODS The 5'-untranslated region of GBV-C was amplified from serum samples of 17 Japanese patients. Polymerase chain reaction-amplified products were directly sequenced and the obtained sequences were analysed by comparing them with the IRES structure of other viruses. RESULTS Fifteen of the 17 (88%) GBV-C strains in our patients were classified as being Asian type. The box-A-like sequence (UUUC) and box-B-like sequence (AUCAUGG) observed in the IRES of picornaviruses were highly conserved in all the strains. Based on pair-wise comparisons with the multiple alignment data, overall sequence divergence for the 5'-terminus was 2.9-12%. When compared with the proposed secondary structure of the IRES model, the sequence divergences of the Asian-type GBV-C were higher at the regions of loop structures and lower at the regions of double-stranded RNA. The AUG codons, except for the one located at nt 552-554, produced truncated polyproteins or were not in-frame with the putative protein. CONCLUSIONS Our examination of the sequence motif of GBV-C supports the proposal that the GBV-C has common structural motifs for IRES at its 5'-untranslated region and the AUG codon at nt 552-554 may be an initiating codon.
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Affiliation(s)
- T Kanda
- First Department of Medicine, Chiba University School of Medicine, Japan.
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34
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Giménez-Barcons M, Sánchez-Fueyo A, Ampurdanés S, Puig-Basagoiti F, Guilera M, Ibáñez A, Clotet B, Martínez MA, Rodés J, Saiz JC, Sánchez-Tapias JM. Genetic evolution of GB virus C/hepatitis G virus (GBV-C/HGV) under interferon pressure. Antiviral Res 2000; 46:157-70. [PMID: 10854667 DOI: 10.1016/s0166-3542(00)00079-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The epidemiology and clinical features of chronic GBV-C/HGV infection have largely been explored, but there is little information about the mechanisms enabling GBV-C/HGV to cause persistent infection. Since analysis of the genomic variation of GBV-C/HGV under interferon pressure might provide some insight into this issue, we analyzed the nucleotide sequence variation of the 5'NC and NS3 regions in GBV-C/HGV isolates obtained sequentially from seven patients co-infected with HCV and treated with interferon. A reduction of GBV-C/HGV-RNA serum level below the detection limit of the RT-PCR assay was observed during treatment in all patients, but upon interferon withdrawal, viral RNA remained undetectable in only two patients. Among the five patients who did not clear GBV-C/HGV-RNA, viral strains emerging after treatment were identical to those present at baseline in three cases. In a further case, in whom GBV-C/HGV-RNA re-emerged during therapy (breakthrough episode), several mutations appeared in relapse samples. In the remaining patient, with a mixed infection before therapy, only one of the two GBV-C/HGV strains present at baseline was detected upon treatment withdrawal. These data raise the possibility that positive selection may act over GBV-C/HGV genome during interferon therapy, and contribute to persistence of infection with this virus.
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MESH Headings
- Base Sequence
- DNA, Viral/genetics
- Evolution, Molecular
- Flaviviridae/genetics
- Genome, Viral
- Hepatitis, Chronic/drug therapy
- Hepatitis, Chronic/virology
- Hepatitis, Viral, Human/drug therapy
- Hepatitis, Viral, Human/virology
- Humans
- Interferon alpha-2
- Interferon-alpha/pharmacology
- Molecular Sequence Data
- Phylogeny
- RNA, Viral/genetics
- Recombinant Proteins
- Selection, Genetic
- Sequence Homology, Nucleic Acid
- Time Factors
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Affiliation(s)
- M Giménez-Barcons
- Liver Unit, Department of Medicine, Institut d'Investigacions Biomèdiques August Pí i Sunyer (IDIBAPS), Hospital Clinic, Facultad de Medicina, Universidad de Barcelona, Villaroel 170, 08036, Barcelona, Spain
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35
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36
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Abstract
GB virus B (GBV-B) is a recently discovered hepatotropic flavivirus that is distantly related to hepatitis C virus (HCV). We show here that translation of its polyprotein is initiated by internal entry of ribosomes on GBV-B RNA. We analyzed the translational activity of dicistronic RNA transcripts containing wild-type or mutated 5' nontranslated GBV-B RNA (5'NTR) segments, placed between the coding sequences of two reporter proteins, in vitro in rabbit reticulocyte lysate and in vivo in transfected BT7-H cells. We related these results to a previously proposed model of the secondary structure of the GBV-B 5'NTR (M. Honda, et al. RNA 2:955-968, 1996). We identified an internal ribosome entry site (IRES) bounded at its 5' end by structural domain II, a location analogous to the 5' limit of the IRES in both the HCV and pestivirus 5'NTRs. Mutational analysis confirmed the structure proposed for domain II of GBV-B RNA, and demonstrated that optimal IRES-mediated translation is dependent on each of the putative RNA hairpins in this domain, including two stem-loops not present in the HCV or pestivirus structures. IRES activity was also absolutely dependent on (i) phylogenetically conserved, adenosine-containing bulge loops in domain III and (ii) the primary nucleotide sequence of stem-loop IIIe. IRES-directed translation was inhibited by a series of point mutations predicted to stabilize stem-loop IV, which contains the initiator AUG codon in its loop segment. A reporter gene was translated most efficiently when fused directly to the initiator AUG codon, with no intervening downstream GBV-B sequence. This finding indicates that the 3' limit of the GBV-B IRES is at the initiator AUG and that it does not require downstream polyprotein-coding sequence as suggested for the HCV IRES. These results show that the GBV-B IRES, while sharing a common general structure, differs both structurally and functionally from other flavivirus IRES elements.
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Affiliation(s)
- R Rijnbrand
- Department of Microbiology and Immunology, The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-1019, USA
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37
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Rijnbrand RC, Lemon SM. Internal ribosome entry site-mediated translation in hepatitis C virus replication. Curr Top Microbiol Immunol 1999; 242:85-116. [PMID: 10592657 DOI: 10.1007/978-3-642-59605-6_5] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- R C Rijnbrand
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston 77555-1019, USA
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38
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Robaczewska M, Cova L, Podhajska AJ, Falkiewicz B. Hepatitis G virus: molecular organization, methods of detection, prevalence, and disease association. Int J Infect Dis 1999; 3:220-33. [PMID: 10575154 DOI: 10.1016/s1201-9712(99)90030-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
This article reviews data on hepatitis G virus (HGV) prevalence and possible disease associations in various groups of patients. An important fraction of acute or chronic hepatitis cases probably have a viral etiology and are not attributable to known hepatitis viruses. Therefore, researchers continually are looking for new hepatitis viruses. Among the agents found are members of GB hepatitis viruses, including GB-C virus, or HGV. This review presents the history of the discovery of HGV, its molecular biology and some methods of detection; results of clinical and molecular studies of HGV infection also are discussed.
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Affiliation(s)
- M Robaczewska
- Molecular Diagnostics Division, Department of Biotechnology, Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
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39
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Abstract
Hepatitis C virus (HCV) is an important cause of chronic liver disease worldwide. HCV is a positive-strand genotype RNA virus with extensive genetic heterogeneity; HCV isolates define 6 major genotypes, and HCV circulates within an infected individual as a number of closely related but distinct species, termed a quasispecies. This article reviews characteristic aspects of HCV molecular biology and their implications for treatment and vaccine development.
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Affiliation(s)
- X Forns
- Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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40
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Skulachev MV, Ivanov PA, Karpova OV, Korpela T, Rodionova NP, Dorokhov YL, Atabekov JG. Internal initiation of translation directed by the 5'-untranslated region of the tobamovirus subgenomic RNA I(2). Virology 1999; 263:139-54. [PMID: 10544089 DOI: 10.1006/viro.1999.9928] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previously we reported that, unlike RNA of typical tobamoviruses, the translation of the coat protein (CP) gene of a crucifer-infecting tobamovirus (crTMV) in vitro occurred by an internal ribosome entry mechanism mediated by the 148-nt region that contained an internal ribosome entry site (IRES(CP,148)(CR)). The equivalent 148-nt sequence from TMV U1 RNA (U1(CP,148)(SP)) was incapable of promoting internal initiation. In the present work, we have found that the 228-nt region upstream of the movement protein (MP) gene of crTMV RNA (IRES(MP,228)(CR)) contained an IRES element that directed in vitro translation of the 3'-proximal reporter genes from chimeric dicistronic transcripts. Surprisingly, the equivalent 228-nt sequence upstream from the MP gene of TMV U1 directed translation of the downstream gene of a dicistronic transcripts as well. Consequently this sequence was termed IRES(MP,228)(U1). It was shown that IRES(MP,228)(CR), IRES(MP,228)(U1), and IRES(CP,148)(CR) could mediate expression of the 3'-proximal GUS gene from dicistronic 35S promoter-based constructs in vivo in experiments on transfection of tobacco protoplasts and particle bombardment of Nicotiana benthamiana leaves. The results indicated that an IRES element was located within the 75-nt region upstream of MP gene (IRES(MP,75)), which corresponded closely to the length of the 5'UTR of TMV subgenomic RNA (sgRNA) I(2). The RNA transcripts structurally equivalent to I(2) sgRNAs of TMV U1 and crTMV, but containing a hairpin structure (H) immediately upstream of IRES(MP,75) (HIRES(MP), (75)(CR)-MP-CP-3'UTR; HIRES(MP,75)(U1)-MP-CP-3'UTR), were able to express the MP gene in vitro. The capacity of HIRES(MP,75)(CR) sequence for mediating internal translation of the 3'-proximal GUS gene in vivo, in tobacco protoplasts, was demonstrated. We suggested that expression of the MP gene from I(2) sgRNAs might proceed via internal ribosome entry pathway mediated by IRES(MP) element contained in the 75-nt 5'UTR. Our results admit that a ribosome scanning mechanism of the MP gene expression from I(2) sgRNA operates concurrently.
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Affiliation(s)
- M V Skulachev
- Department of Virology, Moscow State University, Moscow, 119899, Russia
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41
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Shimizu YK, Hijikata M, Kiyohara T, Kitamura Y, Yoshikura H. Replication of GB virus C (hepatitis G virus) in interferon-resistant Daudi cells. J Virol 1999; 73:8411-4. [PMID: 10482592 PMCID: PMC112859 DOI: 10.1128/jvi.73.10.8411-8414.1999] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We previously reported that Daudi cells, a Burkitt's lymphoma cell line, were capable of supporting productive infection of hepatitis C virus (HCV). During continual cultivation after HCV infection, the culture became resistant to interferons (IFNs). This resistant cell line, coded as H-903, was used as host cells for replication of GB virus C (GBV-C), also known as hepatitis G virus. GBV-C RNA was detected in the culture by reverse transcription-PCR for more than 130 days after inoculation, while it was detected for 44 days but not later in the parental IFN-sensitive Daudi cells. Productive infection of GBV-C in the H-903 system was confirmed by serially inoculating supernatants from infected cultures into uninfected cells. The viral E2 antigen was detected by immunofluorescence in the cells inoculated with the fifth passage of GBV-C. The presumed capsid-coding region of the viral genome in the inoculum, in the serially passaged virus, or in the virus produced by a long-term culture was only 16 amino acids long, suggesting that the GBV-C with a short core sequence was replication competent.
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Affiliation(s)
- Y K Shimizu
- Department of Infectious Diseases and Vaccine Control, National Institute of Infectious Diseases, Tokyo 208-0011, Japan.
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42
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Tucker TJ, Smuts H, Eickhaus P, Robson SC, Kirsch RE. Molecular characterization of the 5? non-coding region of South African GBV-C/HGV isolates: Major deletion and evidence for a fourth genotype. J Med Virol 1999. [DOI: 10.1002/(sici)1096-9071(199909)59:1<52::aid-jmv9>3.0.co;2-d] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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43
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Xiang J, Daniels KJ, Soll DR, Schmidt WN, Labrecque DR, Stapleton JT. Visualization and characterization of GB virus-C particles: evidence for a nucleocapsid. J Viral Hepat 1999; 6 Suppl 1:16-22. [PMID: 10760030 DOI: 10.1046/j.1365-2893.1999.00003.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
GB virus type C (GBV-C) is a member of the hepacivirus genus within the Flaviviradae. Persistent GBV-C infection is common in humans, yet it remains unclear if GBV-C causes any disease. Although GBV-C infection has been associated with acute non-A to non-E post-transfusion hepatitis, it does not appear to cause chronic hepatitis. GBV-C is closely related to hepatitis C virus (HCV), but indirect evidence suggests that it does not encode a core protein at the amino terminus of the open reading frame (ORF). This has led to speculation that GBV-C does not have a nucleocapsid. We evaluated the buoyant density of GBV-C, and found very low density particles consistent with virions, and intermediate density particles consistent with nucleocapsids in GBV-C-infected people. In addition, electron microscopy demonstrated an apparent nucleocapsid within an enveloped particle. Although these biophysical data strongly suggest that GBV-C utilizes a nucleocapsid, they do not indicate the origin of the protein content of this particle. To assess this, we evaluated patient plasma for reactivity with a synthetic oligopeptide representing a conserved region near the amino terminus of the predicted ORF. Specific antibody was detected in some individuals, similar to data of Feucht et al. who identified antibody against a recombinant core protein in GBV-C-infected people. These data indicate that GBV-C particles contain nucleocapsids. At least in some patients, the region upstream of the GBV-C E1 protein coding region appears to be expressed, and this region may represent the structural protein of the nucleocapsid.
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Affiliation(s)
- J Xiang
- Departments of Internal Medicine, Iowa City Veterans Administration Medical Center and The University of Iowa College of Medicine; Iowa City, Iowa 52242, USA
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44
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Psaridi L, Georgopoulou U, Varaklioti A, Mavromara P. Mutational analysis of a conserved tetraloop in the 5' untranslated region of hepatitis C virus identifies a novel RNA element essential for the internal ribosome entry site function. FEBS Lett 1999; 453:49-53. [PMID: 10403373 DOI: 10.1016/s0014-5793(99)00662-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The 5' untranslated region of hepatitis C virus RNA forms an extensive secondary structure including several hairpin motifs and mediates translation initiation by an internal ribosome entry site-dependent pathway. We report, here, an extensive mutagenesis analysis of a highly conserved tetraloop in the 5' untranslated region of hepatitis C virus, namely hairpin IIIe (295'-GAUA-298'). Our results demonstrate that hairpin IIIe is essential for the internal ribosome entry site function. Moreover, they indicate the importance of the primary structure of this motif because mutations in all four nucleotides of the loop caused a severe loss of internal ribosome entry site activity. These data represent the first experimental evidence for the functional significance of tetraloops in internal ribosome entry site-driven translation of hepatitis C virus.
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Affiliation(s)
- L Psaridi
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Athens, Greece
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45
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Fogeda M, Navas S, Martín J, Casqueiro M, Rodríguez E, Arocena C, Carreño V. In vitro infection of human peripheral blood mononuclear cells by GB virus C/Hepatitis G virus. J Virol 1999; 73:4052-61. [PMID: 10196301 PMCID: PMC104184 DOI: 10.1128/jvi.73.5.4052-4061.1999] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
GB virus C (GBV-C), also known as hepatitis G virus, is a recently discovered flavivirus-like RNA agent with unclear pathogenic implications. To investigate whether human peripheral blood mononuclear cells (PBMC) are susceptible to in vitro GBV-C infection, we have incubated PBMC from four healthy blood donors with a human GBV-C RNA-positive serum. By means of (i) strand-specific reverse transcription-PCR, cloning, and sequencing; (ii) sucrose ultracentrifugation and RNase sensitivity assays; (iii) fluorescent in situ hybridization; and (iv) Western blot analysis, it has been demonstrated that GBV-C is able to infect in vitro cells and replicate for as long as 30 days under the conditions developed in our cell culture system. The concentration of GBV-C RNA increased during the second and third weeks of culture. The titers of the genomic strand were 10 times higher than the titers of the antigenomic strand. In addition, the same predominant GBV-C sequence was found in all PBMC cultures and in the in vivo-GBV-C-infected PBMC isolated from the donor of the inoculum. GBV-C-specific fluorescent in situ hybridization signals were confined to the cytoplasm of cells at different times during the culture period. Finally, evidence obtained by sucrose ultracentrifugation, RNase sensitivity assays, and Western blot analysis of the culture supernatants suggests that viral particles are released from in vitro-GBV-C-infected PBMC. In conclusion, our study has demonstrated, for the first time, GBV-C replication in human lymphoid cells under experimental in vitro infection conditions.
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Affiliation(s)
- M Fogeda
- Department of Hepatology, Fundación Jiménez Díaz, and Fundación para el Estudio de las Hepatitis Virales, Madrid, Spain
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46
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Cong M, Fried MW, Lambert S, Lopareva EN, Zhan M, Pujol FH, Thyagarajan SP, Byun KS, Fields HA, Khudyakov YE. Sequence heterogeneity within three different regions of the hepatitis G virus genome. Virology 1999; 255:250-9. [PMID: 10069950 DOI: 10.1006/viro.1998.9592] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two sets of primers derived from the 5'-terminal region and the NS5 region of the hepatitis G virus (HGV) genome were used to amplify PCR fragments from serum specimens obtained from different parts of the world. All PCR fragments from the 5'-terminal region (5'-PCR, n = 56) and from the NS5 region (NS5-PCR, n = 85) were sequenced and compared to corresponding published HGV sequences. The range of nucleotide sequence similarity varied from 74 and 78% to 100% for 5'-PCR and NS5-PCR fragments, respectively. Additionally, five overlapping PCR fragments comprising an approximately 2.0-kb structural region of the HGV genome were sequenced from each of five sera obtained from three United States residents. These sequences were compared to 20 published sequences comprising the same region of the HGV genome. Nucleotide and deduced amino acid sequences obtained from different individuals were homologous from 82.9 to 93. 6% and from 90.4 to 99.0%, respectively. Sequences obtained from follow-up specimens were almost identical. Comparative analysis of deduced amino acid sequences of the HGV structural proteins and hepatitis C virus (HCV) structural proteins combined with an analysis of predicted secondary structures and hydrophobic profiles allowed prediction of processing sites within the HGV structural proteins. A phylogenetic sequence analysis performed on the 2.0-kb structural region supports the existence of three previously identified HGV genetic groups. However, phylogenetic analysis performed on only small DNA fragments yielded inconsistent genetic grouping and failed to confirm the existence of genetic groups. Thus, in contrast to HCV where almost any region can be used for genotyping, only large or carefully selected genome fragments can be used to identify consistent HGV genetic groups.
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Affiliation(s)
- M Cong
- Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Atlanta, Georgia, 30333, USA
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47
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Isaacson AH, Bhardwaj B, Qian K, Davis GL, Kato T, Mizokami M, Lau JY. Hepatitis G virus infection in renal transplant recipients. J Viral Hepat 1999; 6:151-60. [PMID: 10607227 DOI: 10.1046/j.1365-2893.1999.00149.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
To determine the prevalence and clinical significance of hepatitis G virus (HGV)/GB virus C (GBV-C) infection in renal transplant recipients, prospectively collected serum samples from a cohort of cadaveric renal transplant patients were studied for the presence of HGV RNA using a sensitive reverse transcription 'nested'-polymerase chain reaction (RT-PCR) based on primers derived from the 5' untranslated region. All positive PCR amplicons were sequenced bidirectionally and aligned. The nucleotide substitution rate was estimated by the 6-parameter method, and a phylogenetic tree was constructed using the Neighbour-joining method. HGV RNA was detected in 11/93 (12%) patients pretransplant and in 15/90 (17%) patients 1-4 years post-transplant. All PCR amplicons were confirmed to be specific for HGV by sequencing. Phylogenetic tree construction revealed that 17 PCR amplicons had sequences related to HGV and one had a sequence related to GBV-C. Two HGV RNA-positive patients pretransplant became HGV RNA negative post-transplant, and seven HGV RNA-negative patients pretransplant became HGV RNA positive post-transplant. There was no relationship between hepatitis C virus (HCV) and HGV infection. There were also no differences in age, gender distribution, ethnic origin, the total number of blood units transfused and either graft or patient survival between patients who were positive or negative for HGV RNA. We conclude that HGV infection is common among renal transplant candidates and recipients. Most of the isolates had sequences related to the HGV prototype. HGV infection does not appear to adversely affect clinical outcome in renal transplant recipients during early follow-up.
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Affiliation(s)
- A H Isaacson
- Section of Hepatobiliary Diseases, Division of Gastroenterology, Hepatology, and Nutrition, University of Florida, Gainesville, USA
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48
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Charrel RN, Attoui H, De Micco P, de Lamballerie X. The complete coding sequence of a European isolate of GB-C/hepatitis G virus. Biochem Biophys Res Commun 1999; 255:432-7. [PMID: 10049726 DOI: 10.1006/bbrc.1999.0205] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined the full-length coding sequence of a GB-C/hepatitis G (GBV-C/HGV) virus isolate (AUQ) obtained from a French blood donor. The genome of AUQ strain contains a long open reading frame encoding 2842 amino acid residues. Comparison with the 33 complete genome sequences so far available from the databases indicates that the full-length sequence of GBV-C/HGV AUQ showed 9.0-14.1% nucleotide sequence divergence but only 1.6-5.3% at the amino acid level. Analysis of the potential cleavage sites of the polyprotein found that they were remarkably conserved among all sequences. Although phylogenetic studies based on partial genomic sequences suggested a clusterization according to the geographical origin, analysis based on full-length polyprotein did not provide similar conclusions.
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Affiliation(s)
- R N Charrel
- Laboratoire de Virologie Moléculaire, Transfusionnelle et Tropicale, Faculté de Médecine, Marseille, France.
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49
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Honda M, Beard MR, Ping LH, Lemon SM. A phylogenetically conserved stem-loop structure at the 5' border of the internal ribosome entry site of hepatitis C virus is required for cap-independent viral translation. J Virol 1999; 73:1165-74. [PMID: 9882318 PMCID: PMC103937 DOI: 10.1128/jvi.73.2.1165-1174.1999] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Hepatitis C virus (HCV) initiates translation of its polyprotein under the control of an internal ribosome entry site (IRES) that comprises most of the 341-nucleotide (nt) 5' nontranslated RNA (5'NTR). A comparative analysis of related flaviviral sequences suggested that an RNA segment for which secondary structure was previously ill defined (domain II, nt 44 to 118) forms a conserved stem-loop that is located at the 5' border of the HCV IRES and thus may function in viral translation. This prediction was tested by a mutational analysis of putative helical structures that examined the impact of both covariant and noncovariant nucleotide substitutions on IRES activity in vivo and in vitro. Results of these experiments provide support for predicted base pair interactions between nt 44 to 52 and 111 to 118 and between nt 65 to 70 and 97 to 102 of the HCV 5'NTR. Substitutions at either nt 45 and 46 or nt 116 and 117 resulted in reciprocal changes in V1 nuclease cleavage patterns within the opposing strand of the putative helix, consistent with the predicted base pair interactions. IRES activity was highly dependent on maintenance of the stem-loop II structure but relatively tolerant of covariant nucleotide substitutions within predicted helical segments. Sequence alignments suggested that the deduced domain II structure is conserved within the IRESs of pestiviruses as well as the novel flavivirus GB virus B. Despite marked differences in primary nucleotide sequence within conserved helical segments, the sequences of the intervening single-stranded loop segments are highly conserved in these different viruses. This suggests that these segments of the viral RNA may interact with elements of the host translational machinery that are broadly conserved among different mammalian species.
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Affiliation(s)
- M Honda
- First Department of Internal Medicine, Kanazawa University, Kanazawa, Japan
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50
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Birkenmeyer LG, Desai SM, Muerhoff AS, Leary TP, Simons JN, Montes CC, Mushahwar IK. Isolation of a GB virus-related genome from a chimpanzee. J Med Virol 1998; 56:44-51. [PMID: 9700632 DOI: 10.1002/(sici)1096-9071(199809)56:1<44::aid-jmv8>3.0.co;2-n] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recently, two new flaviviruses, GB virus A (GBV-A) and GB virus B (GBV-B), were identified in the plasma of a tamarin infected with the hepatitis GB agent. A third virus, GB virus C (GBV-C), was subsequently identified in humans. In the current study, representational difference analysis (RDA) was used to search for a new virus in the serum of a chimpanzee that developed acute resolving hepatitis following inoculation with a pool of chimpanzee plasma. The plasma pool originated from serial passages of a human sample containing virus-like particles. Numerous cDNA clones were obtained that exhibited 62-80% identity with GBV-C. With the exception of the extreme 5' and 3' ends, the complete viral genome was sequenced, revealing a single large open reading frame encoding a 2833 amino acid polyprotein that contains two envelope proteins, two proteases, a helicase, and an RNA-dependent RNA polymerase. Phylogenetic analysis of the new virus indicates that it is closely related to GBV-C, yet still sufficiently divergent as to be placed in a separate group, tentatively labeled GB virus Ctroglodytes (GBV-Ctro). Numerous human samples were screened by reverse transcriptase-polymerase chain reaction (RT-PCR), but GBV-Ctro sequence was not detected. However, a second chimpanzee inoculated with the same plasma pool was shown to develop a GBV-Ctro infection. Although isolated from an Old World primate with hepatitis, the primary host of GBV-Ctro and any association with disease remains to be determined.
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Affiliation(s)
- L G Birkenmeyer
- Virus Discovery Group, Experimental Biology Research, Abbott Laboratories, North Chicago, Illinois, USA
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