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Ander SE, Parks MG, Davenport BJ, Li FS, Bosco-Lauth A, Carpentier KS, Sun C, Lucas CJ, Klimstra WB, Ebel GD, Morrison TE. Phagocyte-expressed glycosaminoglycans promote capture of alphaviruses from the blood circulation in a host species-specific manner. PNAS Nexus 2024; 3:pgae119. [PMID: 38560529 PMCID: PMC10978064 DOI: 10.1093/pnasnexus/pgae119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
The magnitude and duration of vertebrate viremia are critical determinants of arbovirus transmission, geographic spread, and disease severity-yet, mechanisms determining arbovirus viremia levels are poorly defined. Previous studies have drawn associations between in vitro virion-glycosaminoglycan (GAG) interactions and in vivo clearance kinetics of virions from blood circulation. From these observations, it is commonly hypothesized that GAG-binding virions are rapidly removed from circulation due to ubiquitous expression of GAGs by vascular endothelial cells, thereby limiting viremia. Using an in vivo model for viremia, we compared the vascular clearance of low and enhanced GAG-binding viral variants of chikungunya, eastern- (EEEV), and Venezuelan- (VEEV) equine encephalitis viruses. We find GAG-binding virions are more quickly removed from circulation than their non-GAG-binding variant; however individual clearance kinetics vary between GAG-binding viruses, from swift (VEEV) to slow removal from circulation (EEEV). Remarkably, we find phagocytes are required for efficient vascular clearance of some enhanced GAG-binding virions. Moreover, transient depletion of vascular heparan sulfate impedes vascular clearance of only some GAG-binding viral variants and in a phagocyte-dependent manner, implying phagocytes can mediate vascular GAG-virion interactions. Finally, in direct contrast to mice, we find enhanced GAG-binding EEEV is resistant to vascular clearance in avian hosts, suggesting the existence of species-specificity in virion-GAG interactions. In summary, these data support a role for GAG-mediated clearance of some viral particles from the blood circulation, illuminate the potential of blood-contacting phagocytes as a site for GAG-virion binding, and suggest a role for species-specific GAG structures in arbovirus ecology.
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Affiliation(s)
- Stephanie E Ander
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - M Guston Parks
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Bennett J Davenport
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Frances S Li
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Angela Bosco-Lauth
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Kathryn S Carpentier
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Chengqun Sun
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Cormac J Lucas
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - William B Klimstra
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Gregory D Ebel
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Thomas E Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
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Ander SE, Parks MG, Davenport BJ, Li FS, Bosco-Lauth A, Carpentier KS, Sun C, Lucas CJ, Klimstra WB, Ebel GD, Morrison TE. Phagocyte-expressed glycosaminoglycans promote capture of alphaviruses from the blood circulation in a host species-specific manner. bioRxiv 2023:2023.08.09.552690. [PMID: 37609165 PMCID: PMC10441409 DOI: 10.1101/2023.08.09.552690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The magnitude and duration of vertebrate viremia are critical determinants of arbovirus transmission, geographic spread, and disease severity-yet, mechanisms determining arbovirus viremia levels are poorly defined. Previous studies have drawn associations between in vitro virion-glycosaminoglycan (GAG) interactions and in vivo clearance kinetics of virions from blood circulation. From these observations, it is commonly hypothesized that GAG-binding virions are rapidly removed from circulation due to ubiquitous expression of GAGs by vascular endothelial cells, thereby limiting viremia. Using an in vivo model for viremia, we compared the vascular clearance of low and enhanced GAG-binding viral variants of chikungunya (CHIKV), eastern-(EEEV), and Venezuelan-(VEEV) equine encephalitis viruses. We find GAG-binding virions are more quickly removed from circulation than their non-GAG-binding variant; however individual clearance kinetics vary between GAG-binding viruses, from swift (VEEV) to slow removal from circulation (EEEV). Remarkably, we find phagocytes are required for efficient vascular clearance of some enhanced GAG-binding virions. Moreover, transient depletion of vascular heparan sulfate (HS) impedes vascular clearance of only some GAG-binding viral variants and in a phagocyte-dependent manner, implying phagocytes can mediate vascular GAG-virion interactions. Finally, in direct contrast to mice, we find enhanced GAG-binding EEEV is resistant to vascular clearance in avian hosts, suggesting the existence of species-specificity in virion-GAG interactions. In summary, these data support a role for GAG-mediated clearance of some viral particles from the blood circulation, illuminate the potential of blood-contacting phagocytes as a site for GAG-virion binding, and suggest a role for species-specific GAG structures in arbovirus ecology. Significance Statement Previously, evidence of arbovirus-GAG interactions in vivo has been limited to associations between viral residues shown to promote enhanced GAG-binding phenotypes in vitro and in vivo phenotypes of viral dissemination and pathogenesis. By directly manipulating host GAG expression, we identified virion-GAG interactions in vivo and discovered a role for phagocyte-expressed GAGs in viral vascular clearance. Moreover, we observe species-specific differences in viral vascular clearance of enhanced GAG-binding virions between murine and avian hosts. These data suggest species-specific variation in GAG structure is a mechanism to distinguish amplifying from dead-end hosts for arbovirus transmission.
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Li FS, Carpentier KS, Hawman DW, Lucas CJ, Ander SE, Feldmann H, Morrison TE. Species-specific MARCO-alphavirus interactions dictate chikungunya virus viremia. Cell Rep 2023; 42:112418. [PMID: 37083332 DOI: 10.1016/j.celrep.2023.112418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/23/2023] [Accepted: 04/04/2023] [Indexed: 04/22/2023] Open
Abstract
Arboviruses are public health threats that cause explosive outbreaks. Major determinants of arbovirus transmission, geographic spread, and pathogenesis are the magnitude and duration of viremia in vertebrate hosts. Previously, we determined that multiple alphaviruses are cleared efficiently from murine circulation by the scavenger receptor MARCO (Macrophage receptor with collagenous structure). Here, we define biochemical features on chikungunya (CHIKV), o'nyong 'nyong (ONNV), and Ross River (RRV) viruses required for MARCO-dependent clearance in vivo. In vitro, MARCO expression promotes binding and internalization of CHIKV, ONNV, and RRV via the scavenger receptor cysteine-rich (SRCR) domain. Furthermore, we observe species-specific effects of the MARCO SRCR domain on CHIKV internalization, where those from known amplification hosts fail to promote CHIKV internalization. Consistent with this observation, CHIKV is inefficiently cleared from the circulation of rhesus macaques in contrast with mice. These findings suggest a role for MARCO in determining whether a vertebrate serves as an amplification or dead-end host following CHIKV infection.
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Affiliation(s)
- Frances S Li
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kathryn S Carpentier
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - David W Hawman
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT 59840, USA
| | - Cormac J Lucas
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Stephanie E Ander
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Heinz Feldmann
- Laboratory of Virology, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, MT 59840, USA
| | - Thomas E Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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Lucas CJ, Davenport BJ, Carpentier KS, Tinega AN, Morrison TE. Two Conserved Phenylalanine Residues in the E1 Fusion Loop of Alphaviruses Are Essential for Viral Infectivity. J Virol 2022; 96:e0006422. [PMID: 35416719 PMCID: PMC9093095 DOI: 10.1128/jvi.00064-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 03/13/2022] [Indexed: 11/20/2022] Open
Abstract
Alphaviruses infect cells by a low pH-dependent fusion reaction between viral and host cell membranes that is mediated by the viral E1 glycoprotein. Most reported alphavirus E1 sequences include two phenylalanines (F87 and F95) in the fusion loop, yet the role of these residues in viral infectivity remains to be defined. Following introduction of wild type (WT), E1-F87A, and E1-F95A chikungunya virus (CHIKV) RNA genomes into cells, viral particle production was similar in magnitude. However, CHIKV E1-F87A and E1-F95A virions displayed impaired infectivity compared with WT CHIKV particles. Although WT, E1-F87A, and E1-F95A particles bound cells with similar efficiencies, E1-F87A and E1-F95A particles were unable to undergo fusion and entry into cells. Introduction of an F95A mutation in the E1 fusion loop of Mayaro virus or Venezuelan equine encephalitis virus also resulted in poorly infectious virions. We further tested whether an E1-F87A or E1-F95A mutation could be incorporated into a live-attenuated vaccine strain, CHIKV 181/25, to enhance vaccine safety. Infection of immunocompromised Ifnar1-/- and Irf3-/-Irf5-/-Irf7-/- mice with 181/25E1-F87A or 181/25E1-F95A resulted in 0% mortality, compared with 100% mortality following 181/25 infection. Despite this enhanced attenuation, surviving Ifnar1-/- and Irf3-/-Irf5-/-Irf7-/- mice were protected against virulent virus re-challenge. Moreover, single-dose immunization of WT mice with either 181/25, 181/25E1-F87A, or 181/25E1-F95A elicited CHIKV-specific antibody responses and protected against pathogenic CHIKV challenge. These studies define a critical function for residues E1-F87 and E1-F95 in alphavirus fusion and entry into target cells and suggest that incorporation of these mutations could enhance the safety of live-attenuated alphavirus vaccine candidates. IMPORTANCE Alphaviruses are human pathogens that cause both debilitating acute and chronic musculoskeletal disease and potentially fatal encephalitis. In this study, we determined that two highly conserved phenylalanine residues in the alphavirus E1 glycoprotein are required for fusion of viral and host cell membranes and viral entry into target cells. We further demonstrated that mutation of these phenylalanines results in a substantial loss of viral virulence but not immunogenicity. These data enhance an understanding of the viral determinants of alphavirus entry into host cells and could contribute to the development of new antivirals targeting these conserved phenylalanines or new live-attenuated alphavirus vaccines.
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Affiliation(s)
- Cormac J. Lucas
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Bennett J. Davenport
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Kathryn S. Carpentier
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alex N. Tinega
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Thomas E. Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
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Abstract
Many viruses utilize the lymphohematogenous route for dissemination; however, they may not freely use this highway unchecked. The reticuloendothelial system (RES) is an innate defense system that surveys circulating blood, recognizing and capturing viral particles. Examination of the literature shows that the bulk of viral clearance is mediated by the liver; however, the precise mechanism(s) mediating viral vascular clearance vary between viruses and, in many cases, remains poorly defined. Herein, we summarize what is known regarding the recognition and capture of virions from the circulation prior to the generation of a specific antibody response. We also discuss the consequences of viral capture on viral pathogenesis and the fate of the captor cell. Finally, this understudied topic has implications beyond viral pathogenesis, including effects on arbovirus ecology and the application of virus-vectored gene therapies.
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Affiliation(s)
- Stephanie E. Ander
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Frances S. Li
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Kathryn S. Carpentier
- Department of Natural Sciences, Greensboro College, Greensboro, North Carolina, United States of America
| | - Thomas E. Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America
- * E-mail:
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Carpentier KS, Sheridan RM, Lucas CJ, Davenport BJ, Li FS, Lucas ED, McCarthy MK, Reynoso GV, May NA, Tamburini BAJ, Hesselberth JR, Hickman HD, Morrison TE. MARCO + lymphatic endothelial cells sequester arthritogenic alphaviruses to limit viremia and viral dissemination. EMBO J 2021; 40:e108966. [PMID: 34618370 PMCID: PMC8591538 DOI: 10.15252/embj.2021108966] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 02/02/2023] Open
Abstract
Viremia in the vertebrate host is a major determinant of arboviral reservoir competency, transmission efficiency, and disease severity. However, immune mechanisms that control arboviral viremia are poorly defined. Here, we identify critical roles for the scavenger receptor MARCO in controlling viremia during arthritogenic alphavirus infections in mice. Following subcutaneous inoculation, arthritogenic alphavirus particles drain via the lymph and are rapidly captured by MARCO+ lymphatic endothelial cells (LECs) in the draining lymph node (dLN), limiting viral spread to the bloodstream. Upon reaching the bloodstream, alphavirus particles are cleared from the circulation by MARCO-expressing Kupffer cells in the liver, limiting viremia and further viral dissemination. MARCO-mediated accumulation of alphavirus particles in the draining lymph node and liver is an important host defense mechanism as viremia and viral tissue burdens are elevated in MARCO-/- mice and disease is more severe. In contrast to prior studies implicating a key role for lymph node macrophages in limiting viral dissemination, these findings exemplify a previously unrecognized arbovirus-scavenging role for lymphatic endothelial cells and improve our mechanistic understanding of viremia control during arthritogenic alphavirus infection.
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Affiliation(s)
- Kathryn S Carpentier
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Ryan M Sheridan
- RNA Bioscience InitiativeUniversity of Colorado School of MedicineAuroraCOUSA
| | - Cormac J Lucas
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Bennett J Davenport
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Frances S Li
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Erin D Lucas
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Mary K McCarthy
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Glennys V Reynoso
- Viral Immunity and Pathogenesis UnitLaboratory of Clinical Microbiology and ImmunologyNational Institutes of Allergy and Infectious DiseasesNIHBethesdaMDUSA
| | - Nicholas A May
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
| | - Beth A J Tamburini
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
- Division of Gastroenterology and HepatologyDepartment of MedicineUniversity of Colorado Anschutz Medical Campus School of MedicineAuroraCOUSA
| | - Jay R Hesselberth
- RNA Bioscience InitiativeUniversity of Colorado School of MedicineAuroraCOUSA
- Department of Biochemistry and Molecular GeneticsUniversity of Colorado School of MedicineAuroraCOUSA
| | - Heather D Hickman
- Viral Immunity and Pathogenesis UnitLaboratory of Clinical Microbiology and ImmunologyNational Institutes of Allergy and Infectious DiseasesNIHBethesdaMDUSA
| | - Thomas E Morrison
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraCOUSA
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Carpentier KS, Davenport BJ, Haist KC, McCarthy MK, May NA, Robison A, Ruckert C, Ebel GD, Morrison TE. Discrete viral E2 lysine residues and scavenger receptor MARCO are required for clearance of circulating alphaviruses. eLife 2019; 8:e49163. [PMID: 31596239 PMCID: PMC6839921 DOI: 10.7554/elife.49163] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 10/04/2019] [Indexed: 12/12/2022] Open
Abstract
The magnitude and duration of vertebrate viremia is a critical determinant of arbovirus transmission, geographic spread, and disease severity. We find that multiple alphaviruses, including chikungunya (CHIKV), Ross River (RRV), and o'nyong 'nyong (ONNV) viruses, are cleared from the circulation of mice by liver Kupffer cells, impeding viral dissemination. Clearance from the circulation was independent of natural antibodies or complement factor C3, and instead relied on scavenger receptor SR-A6 (MARCO). Remarkably, lysine to arginine substitutions at distinct residues within the E2 glycoproteins of CHIKV and ONNV (E2 K200R) as well as RRV (E2 K251R) allowed for escape from clearance and enhanced viremia and dissemination. Mutational analysis revealed that viral clearance from the circulation is strictly dependent on the presence of lysine at these positions. These findings reveal a previously unrecognized innate immune pathway that controls alphavirus viremia and dissemination in vertebrate hosts, ultimately influencing disease severity and likely transmission efficiency.
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Affiliation(s)
- Kathryn S Carpentier
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraUnited States
| | - Bennett J Davenport
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraUnited States
| | - Kelsey C Haist
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraUnited States
| | - Mary K McCarthy
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraUnited States
| | - Nicholas A May
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraUnited States
| | - Alexis Robison
- Department of Microbiology, Immunology, and PathologyColorado State UniversityFort CollinsUnited States
| | - Claudia Ruckert
- Department of Microbiology, Immunology, and PathologyColorado State UniversityFort CollinsUnited States
| | - Gregory D Ebel
- Department of Microbiology, Immunology, and PathologyColorado State UniversityFort CollinsUnited States
| | - Thomas E Morrison
- Department of Immunology and MicrobiologyUniversity of Colorado School of MedicineAuroraUnited States
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Abstract
Alphaviruses are important human pathogens that cause diseases ranging from acute and chronic polyarthralgia to encephalitis. Transmitted by mosquito vectors, alphaviruses have high potential for emergence and have initiated several recent epidemics. The innate immune response is critical for controlling the acute phase of alphavirus disease, and the induction of type I interferon (IFN) is essential in this response. In this review, we discuss our current understanding of innate host sensors that initiate antiviral responses following alphavirus infection, and the IFN-induced effector proteins that limit alphavirus replication and dissemination.
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Affiliation(s)
- Kathryn S Carpentier
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Thomas E Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA.
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Carpentier KS, Esparo NM, Child SJ, Geballe AP. A Single Amino Acid Dictates Protein Kinase R Susceptibility to Unrelated Viral Antagonists. PLoS Pathog 2016; 12:e1005966. [PMID: 27780231 PMCID: PMC5079575 DOI: 10.1371/journal.ppat.1005966] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/30/2016] [Indexed: 02/07/2023] Open
Abstract
During millions of years of coevolution with their hosts, cytomegaloviruses (CMVs) have succeeded in adapting to overcome host-specific immune defenses, including the protein kinase R (PKR) pathway. Consequently, these adaptations may also contribute to the inability of CMVs to cross species barriers. Here, we provide evidence that the evolutionary arms race between the antiviral factor PKR and its CMV antagonist TRS1 has led to extensive differences in the species-specificity of primate CMV TRS1 proteins. Moreover, we identify a single residue in human PKR that when mutated to the amino acid present in African green monkey (Agm) PKR (F489S) is sufficient to confer resistance to HCMVTRS1. Notably, this precise molecular determinant of PKR resistance has evolved under strong positive selection among primate PKR alleles and is positioned within the αG helix, which mediates the direct interaction of PKR with its substrate eIF2α. Remarkably, this same residue also impacts sensitivity to K3L, a poxvirus-encoded pseudosubstrate that structurally mimics eIF2α. Unlike K3L, TRS1 has no homology to eIF2α, suggesting that unrelated viral genes have convergently evolved to target this critical region of PKR. Despite its functional importance, the αG helix exhibits extraordinary plasticity, enabling adaptations that allow PKR to evade diverse viral antagonists while still maintaining its critical interaction with eIF2α.
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Affiliation(s)
- Kathryn S. Carpentier
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Nicolle M. Esparo
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Stephanie J. Child
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Adam P. Geballe
- Departments of Microbiology and Medicine, University of Washington, Seattle Washington, and Divisions of Human Biology and Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, Washington
- * E-mail:
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