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Großkopf AK, Schlagowski S, Fricke T, Ensser A, Desrosiers RC, Hahn AS. Plxdc family members are novel receptors for the rhesus monkey rhadinovirus (RRV). PLoS Pathog 2021; 17:e1008979. [PMID: 33657166 PMCID: PMC7959344 DOI: 10.1371/journal.ppat.1008979] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 03/15/2021] [Accepted: 02/04/2021] [Indexed: 12/30/2022] Open
Abstract
The rhesus monkey rhadinovirus (RRV), a γ2-herpesvirus of rhesus macaques, shares many biological features with the human pathogenic Kaposi's sarcoma-associated herpesvirus (KSHV). Both viruses, as well as the more distantly related Epstein-Barr virus, engage cellular receptors from the Eph family of receptor tyrosine kinases (Ephs). However, the importance of the Eph interaction for RRV entry varies between cell types suggesting the existence of Eph-independent entry pathways. We therefore aimed to identify additional cellular receptors for RRV by affinity enrichment and mass spectrometry. We identified an additional receptor family, the Plexin domain containing proteins 1 and 2 (Plxdc1/2) that bind the RRV gH/gL glycoprotein complex. Preincubation of RRV with soluble Plxdc2 decoy receptor reduced infection by ~60%, while overexpression of Plxdc1 and 2 dramatically enhanced RRV susceptibility and cell-cell fusion of otherwise marginally permissive Raji cells. While the Plxdc2 interaction is conserved between two RRV strains, 26-95 and 17577, Plxdc1 specifically interacts with RRV 26-95 gH. The Plxdc interaction is mediated by a short motif at the N-terminus of RRV gH that is partially conserved between isolate 26-95 and isolate 17577, but absent in KSHV gH. Mutation of this motif abrogated the interaction with Plxdc1/2 and reduced RRV infection in a cell type-specific manner. Taken together, our findings characterize Plxdc1/2 as novel interaction partners and entry receptors for RRV and support the concept of the N-terminal domain of the gammaherpesviral gH/gL complex as a multifunctional receptor-binding domain. Further, Plxdc1/2 usage defines an important biological difference between KSHV and RRV.
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Affiliation(s)
- Anna K. Großkopf
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Sarah Schlagowski
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Thomas Fricke
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Armin Ensser
- Universitätsklinikum Erlangen, Institute for Clinical and Molecular Virology, Erlangen, Germany
| | | | - Alexander S. Hahn
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
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Ensser A, Yasuda K, Lauer W, Desrosiers RC, Hahn AS. Rhesus Monkey Rhadinovirus Isolated from Hemangioma Tissue. Microbiol Resour Announc 2020; 9:e01347-19. [PMID: 32193241 PMCID: PMC7082460 DOI: 10.1128/mra.01347-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 02/28/2020] [Indexed: 11/20/2022] Open
Abstract
We isolated a rhesus monkey rhadinovirus, isolate RRVmmu 209-07, from hemangioma tissue. The virion DNA was sequenced by Illumina-based sequencing. Isolate RRVmmu 209-07 is highly similar overall to RRV 26-95, but considerable differences exist in the 3' region of the genome.
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Affiliation(s)
- Armin Ensser
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University (FAU) Erlangen-Nürnberg, Erlangen, Germany
| | - Koji Yasuda
- New England Primate Research Center, Southborough, Massachusetts, USA
| | - William Lauer
- New England Primate Research Center, Southborough, Massachusetts, USA
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Ronald C Desrosiers
- New England Primate Research Center, Southborough, Massachusetts, USA
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Alexander S Hahn
- New England Primate Research Center, Southborough, Massachusetts, USA
- Junior Research Group Herpesviruses, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany
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A Recombinant Rhesus Monkey Rhadinovirus Deleted of Glycoprotein L Establishes Persistent Infection of Rhesus Macaques and Elicits Conventional T Cell Responses. J Virol 2020; 94:JVI.01093-19. [PMID: 31645449 DOI: 10.1128/jvi.01093-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 09/30/2019] [Indexed: 12/19/2022] Open
Abstract
A replication-competent, recombinant strain of rhesus monkey rhadinovirus (RRV) expressing the Gag protein of SIVmac239 was constructed in the context of a glycoprotein L (gL) deletion mutation. Deletion of gL detargets the virus from Eph family receptors. The ability of this gL-minus Gag recombinant RRV to infect, persist, and elicit immune responses was evaluated after intravenous inoculation of two Mamu-A*01 + RRV-naive rhesus monkeys. Both monkeys responded with an anti-RRV antibody response, and quantitation of RRV DNA in peripheral blood mononuclear cells (PBMC) by real-time PCR revealed levels similar to those in monkeys infected with recombinant gL+ RRV. Comparison of RRV DNA levels in sorted CD3+ versus CD20+ versus CD14+ PBMC subpopulations indicated infection of the CD20+ subpopulation by the gL-minus RRV. This contrasts with results obtained with transformed B cell lines in vitro, in which deletion of gL resulted in markedly reduced infectivity. Over a period of 20 weeks, Gag-specific CD8+ T cell responses were documented by major histocompatibility complex class I (MHC-I) tetramer staining. Vaccine-induced CD8+ T cell responses, which were predominantly directed against the Mamu-A*01-restricted Gag181-189CM9 epitope, could be inhibited by blockade of MHC-I presentation. Our results indicate that gL and the interaction with Eph family receptors are dispensable for the colonization of the B cell compartment following high-dose infection by the intravenous route, which suggests the existence of alternative receptors. Further, gL-minus RRV elicits cellular immune responses that are predominantly canonical in nature.IMPORTANCE Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with a substantial disease burden in sub-Saharan Africa, often in the context of human immunodeficiency virus (HIV) infection. The related rhesus monkey rhadinovirus (RRV) has shown potential as a vector to immunize monkeys with antigens from simian immunodeficiency virus (SIV), the macaque model for HIV. KSHV and RRV engage cellular receptors from the Eph family via the viral gH/gL glycoprotein complex. We have now generated a recombinant RRV that expresses the SIV Gag antigen and does not express gL. This recombinant RRV was infectious by the intravenous route, established persistent infection in the B cell compartment, and elicited strong immune responses to the SIV Gag antigen. These results argue against a role for gL and Eph family receptors in B cell infection by RRV in vivo and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector.
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Großkopf AK, Schlagowski S, Hörnich BF, Fricke T, Desrosiers RC, Hahn AS. EphA7 Functions as Receptor on BJAB Cells for Cell-to-Cell Transmission of the Kaposi's Sarcoma-Associated Herpesvirus and for Cell-Free Infection by the Related Rhesus Monkey Rhadinovirus. J Virol 2019; 93:e00064-19. [PMID: 31118261 PMCID: PMC6639272 DOI: 10.1128/jvi.00064-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 05/15/2019] [Indexed: 12/18/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma and is associated with two B cell malignancies, primary effusion lymphoma (PEL) and the plasmablastic variant of multicentric Castleman's disease. On several adherent cell types, EphA2 functions as a cellular receptor for the gH/gL glycoprotein complex of KSHV. KSHV gH/gL also has previously been found to interact weakly with other members of the Eph family of receptor tyrosine kinases (Ephs), and other A-type Ephs have been shown to be able to compensate for the absence of EphA2 using overexpression systems. However, whether these interactions are of functional consequence at endogenous protein levels has remained unclear so far. Here, we demonstrate for the first time that endogenously expressed EphA7 in BJAB B cells is critical for the cell-to-cell transmission of KSHV from producer iSLK cells to BJAB target cells. The BJAB lymphoblastoid cell line often serves as a model for B cell infection and expresses only low levels of all Eph family receptors other than EphA7. Endogenous EphA7 could be precipitated from the cellular lysate of BJAB cells using recombinant gH/gL, and knockout of EphA7 significantly reduced transmission of KSHV into BJAB target cells. Knockout of EphA5, the second most expressed A-type Eph in BJAB cells, had a similar, although less pronounced, effect on KSHV infection. Receptor function of EphA7 was conserved for cell-free infection by the related rhesus monkey rhadinovirus (RRV), which is relatively even more dependent on EphA7 for infection of BJAB cells.IMPORTANCE Infection of B cells is relevant for two KSHV-associated malignancies, the plasmablastic variant of multicentric Castleman's disease and PEL. Therefore, elucidating the process of B cell infection is important for the understanding of KSHV pathogenesis. While the high-affinity receptor for the gH/gL glycoprotein complex, EphA2, has been shown to function as an entry receptor for various types of adherent cells, the gH/gL complex can also interact with other Eph receptor tyrosine kinases with lower avidity. We analyzed the Eph interactions required for infection of BJAB cells, a model for B cell infection by KSHV. We identified EphA7 as the principal Eph receptor for infection of BJAB cells by KSHV and the related rhesus monkey rhadinovirus. While two analyzed PEL cell lines exhibited high EphA2 and low EphA7 expression, a third PEL cell line, BCBL-1, showed high EphA7 and low EphA2 expression, indicating a possible relevance for KSHV pathology.
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MESH Headings
- Animals
- B-Lymphocytes/metabolism
- B-Lymphocytes/pathology
- B-Lymphocytes/virology
- Cell Line, Tumor
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/metabolism
- Herpesvirus 8, Human/physiology
- Humans
- Lymphoma, Primary Effusion/metabolism
- Lymphoma, Primary Effusion/pathology
- Macaca mulatta
- Receptor, EphA7/genetics
- Receptor, EphA7/metabolism
- Receptors, Virus/genetics
- Receptors, Virus/metabolism
- Rhadinovirus/genetics
- Rhadinovirus/metabolism
- Rhadinovirus/physiology
- Viral Envelope Proteins/genetics
- Viral Envelope Proteins/metabolism
- Virus Internalization
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Affiliation(s)
- Anna K Großkopf
- Junior Research Group Herpesviruses, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany
| | - Sarah Schlagowski
- Junior Research Group Herpesviruses, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany
| | - Bojan F Hörnich
- Junior Research Group Herpesviruses, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany
| | - Thomas Fricke
- Junior Research Group Herpesviruses, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany
| | - Ronald C Desrosiers
- Department of Pathology, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Alexander S Hahn
- Junior Research Group Herpesviruses, German Primate Center-Leibniz Institute for Primate Research, Göttingen, Germany
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Marshall VA, Labo N, Hao XP, Holdridge B, Thompson M, Miley W, Brands C, Coalter V, Kiser R, Anver M, Golubeva Y, Warner A, Jaffe ES, Piatak M, Wong SW, Ohlen C, MacAllister R, Smedley J, Deleage C, Del Prete GQ, Lifson JD, Estes JD, Whitby D. Gammaherpesvirus infection and malignant disease in rhesus macaques experimentally infected with SIV or SHIV. PLoS Pathog 2018; 14:e1007130. [PMID: 30001436 PMCID: PMC6042791 DOI: 10.1371/journal.ppat.1007130] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/31/2018] [Indexed: 12/22/2022] Open
Abstract
Human gammaherpesviruses are associated with malignancies in HIV infected individuals; in macaques used in non-human primate models of HIV infection, gammaherpesvirus infections also occur. Limited data on prevalence and tumorigenicity of macaque gammaherpesviruses, mostly cross-sectional analyses of small series, are available. We comprehensively examine all three-rhesus macaque gammaherpesviruses -Rhesus rhadinovirus (RRV), Rhesus Lymphocryptovirus (RLCV) and Retroperitoneal Fibromatosis Herpesvirus (RFHV) in macaques experimentally infected with Simian Immunodeficiency Virus or Simian Human Immunodeficiency Virus (SIV/SHIV) in studies spanning 15 years at the AIDS and Cancer Virus Program of the Frederick National Laboratory for Cancer Research. We evaluated 18 animals with malignancies (16 lymphomas, one fibrosarcoma and one carcinoma) and 32 controls. We developed real time quantitative PCR assays for each gammaherpesvirus DNA viral load (VL) in malignant and non-tumor tissues; we also characterized the tumors using immunohistochemistry and in situ hybridization. Furthermore, we retrospectively quantified gammaherpesvirus DNA VL and SIV/SHIV RNA VL in longitudinally-collected PBMCs and plasma, respectively. One or more gammaherpesviruses were detected in 17 tumors; generally, one was predominant, and the relevant DNA VL in the tumor was very high compared to surrounding tissues. RLCV was predominant in tumors resembling diffuse large B cell lymphomas; in a Burkitt-like lymphoma, RRV was predominant; and in the fibrosarcoma, RFHV was predominant. Median RRV and RLCV PBMC DNA VL were significantly higher in cases than controls; SIV/SHIV VL and RLCV VL were independently associated with cancer. Local regressions showed that longitudinal VL patterns in cases and controls, from SIV infection to necropsy, differed for each gammaherpesvirus: while RFHV VL increased only slightly in all animals, RLCV and RRV VL increased significantly and continued to increase steeply in cases; in controls, VL flattened. In conclusion, the data suggest that gammaherpesviruses may play a significant role in tumorogenesis in macaques infected with immunodeficiency viruses.
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Affiliation(s)
- Vickie A. Marshall
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Nazzarena Labo
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Xing-Pei Hao
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
- Pathology/Histotechnology Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Benjamin Holdridge
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Marshall Thompson
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Wendell Miley
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Catherine Brands
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Vicky Coalter
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Rebecca Kiser
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Miriam Anver
- Pathology/Histotechnology Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Yelena Golubeva
- Pathology/Histotechnology Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Andrew Warner
- Pathology/Histotechnology Laboratory, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Elaine S. Jaffe
- Laboratory of Pathology, Center for Cancer Research, NCI, Bethesda, Maryland, United States of America
| | - Michael Piatak
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Scott W. Wong
- Vaccine and Gene Therapy Institute, Oregon Health & Sciences University, Beaverton, Oregon, United States of America
| | - Claes Ohlen
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Rhonda MacAllister
- Laboratory Animal Science Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Jeremy Smedley
- Laboratory Animal Science Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Claire Deleage
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Gregory Q. Del Prete
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Jacob D. Estes
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
| | - Denise Whitby
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research sponsored by the National Cancer Institute, Frederick, Maryland, United States of America
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Bielefeldt-Ohmann H, Bruce AG, Howard K, Ikoma M, Thouless ME, Rose TM. Macaque homologs of Kaposi's sarcoma-associated herpesvirus (KSHV) infect germinal center lymphoid cells, epithelial cells in skin and gastrointestinal tract and gonadal germ cells in naturally infected macaques. Virology 2018; 519:106-120. [PMID: 29689462 DOI: 10.1016/j.virol.2018.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/12/2018] [Accepted: 04/10/2018] [Indexed: 12/12/2022]
Abstract
We developed a set of rabbit antisera to characterize infections by the macaque RV2 rhadinovirus homologs of KSHV. We analyzed tissues from rhesus and pig-tailed macaques naturally infected with rhesus rhadinovirus (RRV) or Macaca nemestrina rhadinovirus 2 (MneRV2). Our study demonstrates that RV2 rhadinoviruses have a tropism for epithelial cells, lymphocytes and gonadal germ cells in vivo. We observed latent infections in both undifferentiated and differentiated epithelial cells with expression of the latency marker, LANA. Expression of the early (ORF59) and late (glycoprotein B) lytic markers were detected in highly differentiated cells in epithelial ducts in oral, renal, dermal and gastric mucosal tissue as well as differentiated germ cells in male and female gonads. Our data provides evidence that epithelial and germ cell differentiation in vivo induces rhadinovirus reactivation and suggests that infected epithelial and germ cells play a role in transmission and dissemination of RV2 rhadinovirus infections in vivo.
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Affiliation(s)
| | - A Gregory Bruce
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Pathobiology, University of Washington, Seattle, WA, USA.
| | - Kellie Howard
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Pathobiology, University of Washington, Seattle, WA, USA.
| | - Minako Ikoma
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA.
| | | | - Timothy M Rose
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Pathobiology, University of Washington, Seattle, WA, USA; Department of Pediatrics, University of Washington, Seattle, WA, USA.
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7
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Großkopf AK, Ensser A, Neipel F, Jungnickl D, Schlagowski S, Desrosiers RC, Hahn AS. A conserved Eph family receptor-binding motif on the gH/gL complex of Kaposi's sarcoma-associated herpesvirus and rhesus monkey rhadinovirus. PLoS Pathog 2018; 14:e1006912. [PMID: 29432452 PMCID: PMC5825162 DOI: 10.1371/journal.ppat.1006912] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 02/23/2018] [Accepted: 01/30/2018] [Indexed: 02/05/2023] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) is a human oncogenic virus associated with Kaposi’s sarcoma and two B-cell malignancies. The rhesus monkey rhadinovirus (RRV) is a virus of nonhuman primates that is closely related to KSHV. Eph family receptor tyrosine kinases (Ephs) are cellular receptors for the gH/gL glycoprotein complexes of both KSHV and RRV. Through sequence analysis and mutational screens, we identified conserved residues in the N-terminal domain of KSHV and RRV glycoprotein H that are critical for Eph-binding in vitro. Homology-based structural predictions of the KSHV and RRV gH/gL complexes based on the Epstein-Barr-Virus gH/gL crystal structure located these amino acids in a beta-hairpin on gH, which is likely stabilized by gL and is optimally positioned for protein-protein interactions. Guided by these predictions, we generated recombinant RRV and KSHV strains mutated in the conserved motif as well as an RRV gL null mutant. Inhibition experiments using these mutants confirmed that disruption of the identified Eph-interaction motif or of gL expression resulted in complete detargeting from Ephs. However, all mutants were infectious on all cell types tested, exhibiting normal attachment but a reduction in infectivity of up to one log order of magnitude. While Eph-binding-negative RRV mutants were replication-competent on fibroblasts, their infectivity was comparatively more reduced on endothelial cells with a substantial subpopulation of endothelial cells remaining resistant to infection. Together, this provides evidence for a cell type-specific use of Ephs by RRV. Furthermore, our results demonstrate that gL is dispensable for infection by RRV. Its deletion caused a reduction in infectivity similar to that observed after mutation of Eph-binding residues in gH. Our findings would be compatible with an ability of KSHV and RRV to use other, less efficient entry mediators in lieu of Ephs, although these host factors may not be uniformly expressed by all cells. In immunocompromised individuals in general and in the context of HIV infection in particular, KSHV is a major cause of cancer and B-cell proliferative malignancies. We identified and mutated conserved residues in the N-terminal domain of the gH/gL glycoprotein complex of KSHV and the related monkey virus RRV that are critical for the interaction with cellular receptors from the Eph family. These findings provide important insight into the function of the γ-herpesviral entry machinery. Using recombinant KSHV and RRV carrying these mutations, we demonstrated that while not strictly essential, gH/gL-Eph interactions are important for efficient infection—for RRV also in a cell-specific manner—but not for attachment of KSHV and RRV. The Eph-detargeted virus mutants described in this study can be used to further dissect the requirements for KSHV and RRV entry and to identify potential alternative entry mediators. Domains and residues on the viral glycoproteins with critical roles in receptor recognition, such as the Eph-binding motif described in this paper, can be informative for the design of inhibitory monoclonal antibodies.
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Affiliation(s)
- Anna K. Großkopf
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | - Armin Ensser
- Universitätsklinikum Erlangen, Institute for Clinical and Molecular Virology, Erlangen, Germany
| | - Frank Neipel
- Universitätsklinikum Erlangen, Institute for Clinical and Molecular Virology, Erlangen, Germany
| | - Doris Jungnickl
- Universitätsklinikum Erlangen, Institute for Clinical and Molecular Virology, Erlangen, Germany
| | - Sarah Schlagowski
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
| | | | - Alexander S. Hahn
- German Primate Center - Leibniz Institute for Primate Research, Göttingen, Germany
- * E-mail:
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8
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González Altamiranda E, Manrique JM, Pérez SE, Ríos GL, Odeón AC, Leunda MR, Jones LR, Verna A. Molecular Characterization of the First Bovine Herpesvirus 4 (BoHV-4) Strains Isolated from In Vitro Bovine Embryos production in Argentina. PLoS One 2015; 10:e0132212. [PMID: 26177382 PMCID: PMC4503683 DOI: 10.1371/journal.pone.0132212] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 06/12/2015] [Indexed: 11/19/2022] Open
Abstract
Bovine herpesvirus 4 (BoHV-4) is increasingly considered as responsible for various problems of the reproductive tract. The virus infects mainly blood mononuclear cells and displays specific tropism for vascular endothelia, reproductive and fetal tissues. Epidemiological studies suggest its impact on reproductive performance, and its presence in various sites in the reproductive tract highlights its potential transmission in transfer-stage embryos. This work describes the biological and genetic characterization of BoHV-4 strains isolated from an in vitro bovine embryo production system. BoHV-4 strains were isolated in 2011 and 2013 from granulosa cells and bovine oocytes from ovary batches collected at a local abattoir, used as "starting material" for in vitro production of bovine embryos. Compatible BoHV-4-CPE was observed in the co-culture of granulosa cells and oocytes with MDBK cells. The identity of the isolates was confirmed by PCR assays targeting three ORFs of the viral genome. The phylogenetic analyses of the strains suggest that they were evolutionary unlinked. Therefore it is possible that BoHV-4 ovary infections occurred regularly along the evolution of the virus, at least in Argentina, which can have implications in the systems of in vitro embryo production. Thus, although BoHV-4 does not appear to be a frequent risk factor for in vitro embryo production, data are still limited. This study reveals the potential of BoHV-4 transmission via embryo transfer. Moreover, the high variability among the BoHV-4 strains isolated from aborted cows in Argentina highlights the importance of further research on the role of this virus as an agent with the potential to cause reproductive disease in cattle. The genetic characterization of the isolated strains provides data to better understand the pathogenesis of BoHV-4 infections. Furthermore, it will lead to fundamental insights into the molecular aspects of the virus and the means by which these strains circulate in the herds.
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Affiliation(s)
- Erika González Altamiranda
- Laboratorio de Virología, Departamento de Producción Animal, Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Julieta M. Manrique
- Laboratorio de Virología y Genética Molecular, Facultad de Ciencias Naturales Sede Trelew, Universidad Nacional de la Patagonia San Juan Bosco, Chubut, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Sandra E. Pérez
- Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), Sede Tandil, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Glenda L. Ríos
- Laboratorio de Producción de Embriones, Departamento de Producción Animal, Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce, Buenos Aires, Argentina
| | - Anselmo C. Odeón
- Laboratorio de Virología, Departamento de Producción Animal, Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce, Buenos Aires, Argentina
| | - María R. Leunda
- Laboratorio de Virología, Departamento de Producción Animal, Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce, Buenos Aires, Argentina
| | - Leandro R. Jones
- Laboratorio de Virología y Genética Molecular, Facultad de Ciencias Naturales Sede Trelew, Universidad Nacional de la Patagonia San Juan Bosco, Chubut, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Andrea Verna
- Laboratorio de Virología, Departamento de Producción Animal, Instituto Nacional de Tecnología Agropecuaria (INTA), Balcarce, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- * E-mail:
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9
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Complete genome sequence of Pig-tailed macaque rhadinovirus 2 and its evolutionary relationship with rhesus macaque rhadinovirus and human herpesvirus 8/Kaposi's sarcoma-associated herpesvirus. J Virol 2015; 89:3888-909. [PMID: 25609822 DOI: 10.1128/jvi.03597-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Two rhadinovirus lineages have been identified in Old World primates. The rhadinovirus 1 (RV1) lineage consists of human herpesvirus 8, Kaposi's sarcoma-associated herpesvirus (KSHV), and closely related rhadinoviruses of chimpanzees, gorillas, macaques and other Old World primates. The RV2 rhadinovirus lineage is distinct and consists of closely related viruses from the same Old World primate species. Rhesus macaque rhadinovirus (RRV) is the RV2 prototype, and two RRV isolates, 26-95 and 17577, were sequenced. We determined that the pig-tailed macaque RV2 rhadinovirus, MneRV2, is highly associated with lymphomas in macaques with simian AIDS. To further study the role of rhadinoviruses in the development of lymphoma, we sequenced the complete genome of MneRV2 and identified 87 protein coding genes and 17 candidate microRNAs (miRNAs). A strong genome colinearity and sequence homology were observed between MneRV2 and RRV26-95, although the open reading frame (ORF) encoding the KSHV ORFK15 homolog was disrupted in RRV26-95. Comparison with MneRV2 revealed several genomic anomalies in RRV17577 that were not present in other rhadinovirus genomes, including an N-terminal duplication in ORF4 and a recombinative exchange of more distantly related homologs of the ORF22/ORF47 interacting glycoprotein genes. The comparison with MneRV2 has revealed novel genes and important conservation of protein coding domains and transcription initiation, termination, and splicing signals, which have added to our knowledge of RV2 rhadinovirus genetics. Further comparisons with KSHV and other RV1 rhadinoviruses will provide important avenues for dissecting the biology, evolution, and pathology of these closely related tumor-inducing viruses in humans and other Old World primates. IMPORTANCE This work provides the sequence characterization of MneRV2, the pig-tailed macaque homolog of rhesus rhadinovirus (RRV). MneRV2 and RRV belong to the rhadinovirus 2 (RV2) rhadinovirus lineage of Old World primates and are distinct but related to Kaposi's sarcoma-associated herpesvirus (KSHV), the etiologic agent of Kaposi's sarcoma. Pig-tailed macaques provide important models of human disease, and our previous studies have indicated that MneRV2 plays a causal role in AIDS-related lymphomas in macaques. Delineation of the MneRV2 sequence has allowed a detailed characterization of the genome structure, and evolutionary comparisons with RRV and KSHV have identified conserved promoters, splice junctions, and novel genes. This comparison provides insight into RV2 rhadinovirus biology and sets the groundwork for more intensive next-generation (Next-Gen) transcript and genetic analysis of this class of tumor-inducing herpesvirus. This study supports the use of MneRV2 in pig-tailed macaques as an important model for studying rhadinovirus biology, transmission and pathology.
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Rhesus monkey rhadinovirus uses eph family receptors for entry into B cells and endothelial cells but not fibroblasts. PLoS Pathog 2013; 9:e1003360. [PMID: 23696734 PMCID: PMC3656109 DOI: 10.1371/journal.ppat.1003360] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 03/28/2013] [Indexed: 11/19/2022] Open
Abstract
Cellular Ephrin receptor tyrosine kinases (Ephrin receptors, Ephs) were found to interact efficiently with the gH/gL glycoprotein complex of the rhesus monkey rhadinovirus (RRV). Since EphA2 was recently identified as a receptor for the Kaposi's sarcoma-associated herpesvirus (KSHV) (Hahn et al., Nature Medicine 2012), we analyzed RRV and KSHV in parallel with respect to Eph-binding and Eph-dependent entry. Ten of the 14 Eph proteins, including both A- and B-type, interacted with RRV gH/gL. Two RRV strains with markedly different gH/gL sequences exhibited similar but slightly different binding patterns to Ephs. gH/gL of KSHV displayed high affinity towards EphA2 but substantially weaker binding to only a few other Ephs of the A-type. Productive entry of RRV 26-95 into B cells and into endothelial cells was essentially completely dependent upon Ephs since expression of a GFP reporter cassette from recombinant virus could be blocked to greater than 95% by soluble Eph decoys using these cells. In contrast, entry of RRV into fibroblasts and epithelial cells was independent of Ephs by these same criteria. Even high concentrations and mixtures of soluble Eph decoys were not able to reduce by any appreciable extent the number of fibroblasts and epithelial cells productively entered by RRV. Thus, RRV is similar to its close relative KSHV in the use of Eph family receptors for productive entry into B cells and endothelial cells. However, RRV uses a separate, distinct, Eph-independent pathway for productive entry into fibroblasts and epithelial cells. Whether KSHV also uses an Eph-independent pathway in some circumstances or to some extent remains to be determined.
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Genomic analysis of bovine herpesvirus type 4 (BoHV-4) from Argentina: High genetic variability and novel phylogenetic groups. Vet Microbiol 2012; 160:1-8. [DOI: 10.1016/j.vetmic.2012.04.039] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 04/20/2012] [Accepted: 04/30/2012] [Indexed: 11/17/2022]
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Zhang W, Gao SJ. Exploitation of Cellular Cytoskeletons and Signaling Pathways for Cell Entry by Kaposi's Sarcoma-Associated Herpesvirus and the Closely Related Rhesus Rhadinovirus. Pathogens 2012; 1:102-27. [PMID: 23420076 PMCID: PMC3571711 DOI: 10.3390/pathogens1020102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
As obligate intracellular pathogens, viruses depend on the host cell machinery to complete their life cycle. Kaposi’s sarcoma-associated herpes virus (KSHV) is an oncogenicvirus causally linked to the development of Kaposi’s sarcoma and several other lymphoproliferative malignancies. KSHV entry into cells is tightly regulated by diverse viral and cellular factors. In particular, KSHV actively engages cellular integrins and ubiquitination pathways for successful infection. Emerging evidence suggests that KSHV hijacks both actin and microtubule cytoskeletons at different phases during entry into cells. Here, we review recent findings on the early events during primary infection of KSHV and its closely related primate homolog rhesus rhadinovirus with highlights on the regulation of cellular cytoskeletons and signaling pathways that are important for this phase of virus life cycle.
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Affiliation(s)
| | - Shou-Jiang Gao
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-323-442-8028; Fax: +1-323-442-1721
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Construction and manipulation of a new Kaposi's sarcoma-associated herpesvirus bacterial artificial chromosome clone. J Virol 2012; 86:9708-20. [PMID: 22740391 DOI: 10.1128/jvi.01019-12] [Citation(s) in RCA: 256] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Efficient genetic modification of herpesviruses such as Kaposi's sarcoma-associated herpesvirus (KSHV) has come to rely on bacterial artificial chromosome (BAC) technology. In order to facilitate this approach, we generated a new KSHV BAC clone, called BAC16, derived from the rKSHV.219 virus, which stems from KSHV and Epstein-Barr virus-coinfected JSC1 primary effusion lymphoma (PEL) cells. Restriction enzyme and complete sequencing data demonstrate that the KSHV of JSC1 PEL cells showed a minimal level of sequence variation across the entire viral genome compared to the complete genomic sequence of other KSHV strains. BAC16 not only stably propagated in both Escherichia coli and mammalian cells without apparent genetic rearrangements, but also was capable of robustly producing infectious virions (∼5 × 10(7)/ml). We also demonstrated the utility of BAC16 by generating deletion mutants of either the K3 or K5 genes, whose products are E3 ligases of the membrane-associated RING-CH (MARCH) family. While previous studies have shown that individual expression of either K3 or K5 results in efficient downregulation of the surface expression of major histocompatibility complex class I (MHC-I) molecules, we found that K5, but not K3, was the primary factor critical for the downregulation of MHC-I surface expression during KSHV lytic reactivation or following de novo infection. The data presented here demonstrate the utility of BAC16 for the generation and characterization of KSHV knockout and mutant recombinants and further emphasize the importance of functional analysis of viral genes in the context of the KSHV genome besides the study of individual gene expression.
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Manrique JM, Calvo AY, Jones LR. Phylogenetic analysis of Ostreococcus virus sequences from the Patagonian Coast. Virus Genes 2012; 45:316-26. [PMID: 22674355 DOI: 10.1007/s11262-012-0762-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 05/11/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Julieta M Manrique
- Division of Molecular Biology, Estación de Fotobiología Playa Unión, CC 15 (9103), Playa Unión, Rawson, Chubut, Argentina
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Machiels B, Lété C, Guillaume A, Mast J, Stevenson PG, Vanderplasschen A, Gillet L. Antibody evasion by a gammaherpesvirus O-glycan shield. PLoS Pathog 2011; 7:e1002387. [PMID: 22114560 PMCID: PMC3219721 DOI: 10.1371/journal.ppat.1002387] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 10/04/2011] [Indexed: 12/02/2022] Open
Abstract
All gammaherpesviruses encode a major glycoprotein homologous to the Epstein-Barr virus gp350. These glycoproteins are often involved in cell binding, and some provide neutralization targets. However, the capacity of gammaherpesviruses for long-term transmission from immune hosts implies that in vivo neutralization is incomplete. In this study, we used Bovine Herpesvirus 4 (BoHV-4) to determine how its gp350 homolog--gp180--contributes to virus replication and neutralization. A lack of gp180 had no impact on the establishment and maintenance of BoHV-4 latency, but markedly sensitized virions to neutralization by immune sera. Antibody had greater access to gB, gH and gL on gp180-deficient virions, including neutralization epitopes. Gp180 appears to be highly O-glycosylated, and removing O-linked glycans from virions also sensitized them to neutralization. It therefore appeared that gp180 provides part of a glycan shield for otherwise vulnerable viral epitopes. Interestingly, this O-glycan shield could be exploited for neutralization by lectins and carbohydrate-specific antibody. The conservation of O-glycosylation sites in all gp350 homologs suggests that this is a general evasion mechanism that may also provide a therapeutic target.
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Affiliation(s)
- Bénédicte Machiels
- Immunology-Vaccinology (B43b), Department of Infectious and Parasitic Diseases (B43b), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
| | - Céline Lété
- Immunology-Vaccinology (B43b), Department of Infectious and Parasitic Diseases (B43b), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
| | - Antoine Guillaume
- Immunology-Vaccinology (B43b), Department of Infectious and Parasitic Diseases (B43b), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
| | - Jan Mast
- Department Biocontrole, Research Unit Electron Microscopy, Veterinary and Agrochemical Research Centre, CODA-CERVA, Groeselenberg, Ukkel, Belgium
| | - Philip G. Stevenson
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Alain Vanderplasschen
- Immunology-Vaccinology (B43b), Department of Infectious and Parasitic Diseases (B43b), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
| | - Laurent Gillet
- Immunology-Vaccinology (B43b), Department of Infectious and Parasitic Diseases (B43b), Faculty of Veterinary Medicine, University of Liège, Liège, Belgium
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Nagamine B, Jones L, Tellgren-Roth C, Cavender J, Bratanich AC. A novel gammaherpesvirus isolated from a black-tailed prairie dog (Cynomys ludovicianus). Arch Virol 2011; 156:1835-40. [PMID: 21630099 DOI: 10.1007/s00705-011-1024-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 05/06/2011] [Indexed: 11/27/2022]
Abstract
A new gammaherpesvirus, tentatively named cynomys herpesvirus 1 (CynGHV-1), was isolated from a black-tailed prairie dog (Cynomys ludovicianus). CynGHV-1 replicated cytopathogenically to moderate titers in various cell lines. Ten kb of the CynGHV-1 genome was sequenced using degenerate PCR and genomic cloning. Sequence similarities were found to different genes from known gammaherpesviruses. Phylogenetic analysis suggested that CynGHV-1 was in fact a novel virus closely related to representatives of different genera and unclassified members of the subfamily Gammaherpesvirinae. However, CynGHV-1 could not be assigned to any particular genus and therefore remains unclassified.
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Affiliation(s)
- Brandy Nagamine
- Department of Veterinary Science, University of Wyoming, Laramie, WY 82070, USA
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White JA, Yang X, Todd PA, Lerche NW. Longitudinal patterns of viremia and oral shedding of rhesus rhadinovirus and retroperitoneal fibromatosis herpesviruses in age-structured captive breeding populations of rhesus Macaques (Macaca mulatta). Comp Med 2011; 61:60-70. [PMID: 21819683 PMCID: PMC3060420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/09/2010] [Accepted: 09/14/2010] [Indexed: 05/31/2023]
Abstract
Rhesus rhadinovirus (RRV) and retroperitoneal fibromatosis herpesvirus (RFHV), 2 closely related γ2 herpesviruses, are endemic in breeding populations of rhesus macaques at our institution. We previously reported significantly different prevalence levels, suggesting the transmission dynamics of RRV and RFHV differ with regard to viral shedding and infectivity. We designed a longitudinal study to further examine the previously observed differences between RRV and RFHV prevalence and the potential influence of age, season, and housing location on the same 90 rhesus macaques previously studied. Virus- and host-genome-specific real-time PCR assays were used to determine viral loads for both RRV and RFHV in blood and saliva samples collected at 6 time points over an 18-mo period. Proportions of positive animals and viral load in blood and saliva were compared between and within viruses by age group, location, and season by using 2-part longitudinal modeling with Bayesian inferences. Our results demonstrate that age and season are significant determinants, with age as the most significant factor analyzed, of viremia and oral shedding for both RRV and RFHV, and these pathogens exhibit distinctly different patterns of viremia and oral shedding over time within a single population.
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Affiliation(s)
- Jessica A White
- California National Primate Research Center, School of Medicine, University of California, Davis, California, Koelle Lab, University of Washington, Seattle, Washington, USA.
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Rhesus rhadinovirus infection of rhesus fibroblasts occurs through clathrin-mediated endocytosis. J Virol 2010; 84:11709-17. [PMID: 20826690 DOI: 10.1128/jvi.01429-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhesus rhadinovirus (RRV) is a gammaherpesvirus closely related to Kaposi's sarcoma-associated herpesvirus (KSHV), an oncogenic virus linked to the development of Kaposi's sarcoma and several other lymphoproliferative diseases, including primary effusion lymphoma and multicentric Castleman's disease. RRV naturally infects rhesus macaques and induces lymphoproliferative diseases under experimental conditions, making it an excellent model for the study of KSHV. Unlike KSHV, which grows poorly in cell culture, RRV replicates efficiently in rhesus fibroblasts (RFs). In this study, we have characterized the entry pathway of RRV in RFs. Using a luciferase-expressing recombinant RRV (RRV-luciferase), we show that the infectivity of RRV is reduced by inhibitors of endosomal acidification. RRV infectivity is also reduced by inhibitors of clathrin-mediated but not caveola-mediated endocytosis, indicating that RRV enters into RFs via clathrin-mediated endocytosis. Using a red fluorescent protein (RFP)-expressing recombinant RRV (RRV-RFP), we show that RRV particles are colocalized with markers of endocytosis (early endosome antigen 1) and clathrin-mediated endocytosis (clathrin heavy chain) during entry into RFs. RRV particles are also colocalized with transferrin, which enters cells by clathrin-mediated endocytosis, but not with cholera toxin B, which enters cells by caveola-mediated endocytosis. Inhibition of clathrin-mediated endocytosis with a dominant-negative construct of EPS15, an essential component of clathrin-coated pits, blocked the entry of RRV into RFs. Together, these results indicate that RRV entry into RFs is mediated by clathrin-mediated endocytosis.
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