1
|
Varkoly K, Beladi R, Hamada M, McFadden G, Irving J, Lucas AR. Viral SERPINS-A Family of Highly Potent Immune-Modulating Therapeutic Proteins. Biomolecules 2023; 13:1393. [PMID: 37759793 PMCID: PMC10526531 DOI: 10.3390/biom13091393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/03/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
Serine protease inhibitors, SERPINS, are a highly conserved family of proteins that regulate serine proteases in the central coagulation and immune pathways, representing 2-10% of circulating proteins in the blood. Serine proteases form cascades of sequentially activated enzymes that direct thrombosis (clot formation) and thrombolysis (clot dissolution), complement activation in immune responses and also programmed cell death (apoptosis). Virus-derived serpins have co-evolved with mammalian proteases and serpins, developing into highly effective inhibitors of mammalian proteolytic pathways. Through interacting with extracellular and intracellular serine and cysteine proteases, viral serpins provide a new class of highly active virus-derived coagulation-, immune-, and apoptosis-modulating drug candidates. Viral serpins have unique characteristics: (1) function at micrograms per kilogram doses; (2) selectivity in targeting sites of protease activation; (3) minimal side effects at active concentrations; and (4) the demonstrated capacity to be modified, or fine-tuned, for altered protease targeting. To date, the virus-derived serpin class of biologics has proven effective in a wide range of animal models and in one clinical trial in patients with unstable coronary disease. Here, we outline the known viral serpins and review prior studies with viral serpins, considering their potential for application as new sources for immune-, coagulation-, and apoptosis-modulating therapeutics.
Collapse
Affiliation(s)
- Kyle Varkoly
- Department of Internal Medicine, McLaren Macomb Hospital, Michigan State University College of Human Medicine, 1000 Harrington St., Mt Clemens, MI 48043, USA;
| | - Roxana Beladi
- Department of Neurological Surgery, Ascension Providence Hospital, Michigan State University College of Human Medicine, 16001 W Nine Mile Rd., Southfield, MI 48075, USA;
| | - Mostafa Hamada
- College of Medicine, Kansas City University, 1750 Independence Ave, Kansas City, MO 64106, USA;
- Center for Immunotherapy Vaccines and Virotherapy, Biodesign Institute, Arizona State University, 727 E Tyler St., Tempe, AZ 85287, USA;
| | - Grant McFadden
- Center for Immunotherapy Vaccines and Virotherapy, Biodesign Institute, Arizona State University, 727 E Tyler St., Tempe, AZ 85287, USA;
| | - James Irving
- UCL Respiratory and the Institute of Structural and Molecular Biology, University College London, 5 University Street, London WC1E 6JF, UK
| | - Alexandra R. Lucas
- Center for Immunotherapy Vaccines and Virotherapy, Biodesign Institute, Arizona State University, 727 E Tyler St., Tempe, AZ 85287, USA;
- Center for Personalized Diagnostics, Biodesign Institute, Arizona State University, 727 E Tyler St., Tempe, AZ 85287, USA
| |
Collapse
|
2
|
Epstein-Barr virus EBER1 and murine gammaherpesvirus TMER4 share conserved in vivo function to promote B cell egress and dissemination. Proc Natl Acad Sci U S A 2019; 116:25392-25394. [PMID: 31796588 PMCID: PMC6926008 DOI: 10.1073/pnas.1915752116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The oncogenic gammaherpesviruses, including human Epstein–Barr virus (EBV), human Kaposi’s sarcoma-associated herpesvirus (KSHV), and murine gammaherpesvirus 68 (MHV68, γHV68, MuHV-4) establish life-long latency in circulating B cells. The precise determinants that mediate in vivo gammaherpesvirus latency and tumorigenesis remain unclear. The EBV-encoded RNAs (EBERs) are among the first noncoding RNAs ever identified and have been the subject of decades of studies; however, their biological roles during in vivo infection remain unknown. Herein, we use a series of refined virus mutants to define the active isoform of MHV68 noncoding RNA TMER4 and demonstrate that EBV EBER1 functionally conserves this activity in vivo to promote egress of infected B cells from lymph nodes into peripheral circulation.
Collapse
|
3
|
Bullard WL, Flemington EK, Renne R, Tibbetts SA. Connivance, Complicity, or Collusion? The Role of Noncoding RNAs in Promoting Gammaherpesvirus Tumorigenesis. Trends Cancer 2018; 4:729-740. [PMID: 30352676 DOI: 10.1016/j.trecan.2018.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 08/20/2018] [Accepted: 09/10/2018] [Indexed: 12/12/2022]
Abstract
EBV and KSHV are etiologic agents of multiple types of lymphomas and carcinomas. The frequency of EBV+ or KSHV+ malignancies arising in immunocompromised individuals reflects the intricate evolutionary balance established between these viruses and their immunocompetent hosts. However, the specific mechanisms by which these pathogens drive tumorigenesis remain poorly understood. In recent years an enormous array of cellular and viral noncoding RNAs (ncRNAs) have been discovered, and host ncRNAs have been revealed as contributory factors to every single cancer hallmark cellular process. As new evidence emerges that gammaherpesvirus ncRNAs also alter host processes and viral factors dysregulate host ncRNA expression, and as novel viral ncRNAs continue to be discovered, we examine the contribution of small, non-miRNA ncRNAs and long ncRNAs to gammaherpesvirus tumorigenesis.
Collapse
Affiliation(s)
- Whitney L Bullard
- Department of Molecular Genetics and Microbiology, UF Health Cancer Center, University of Florida, Gainesville, FL, USA
| | - Erik K Flemington
- Department of Pathology, Tulane Cancer Center, Tulane University, New Orleans, LA, USA
| | - Rolf Renne
- Department of Molecular Genetics and Microbiology, UF Health Cancer Center, University of Florida, Gainesville, FL, USA
| | - Scott A Tibbetts
- Department of Molecular Genetics and Microbiology, UF Health Cancer Center, University of Florida, Gainesville, FL, USA.
| |
Collapse
|
4
|
O’Flaherty BM, Matar CG, Wakeman BS, Garcia A, Wilke CA, Courtney CL, Moore BB, Speck SH. CD8+ T Cell Response to Gammaherpesvirus Infection Mediates Inflammation and Fibrosis in Interferon Gamma Receptor-Deficient Mice. PLoS One 2015; 10:e0135719. [PMID: 26317335 PMCID: PMC4552722 DOI: 10.1371/journal.pone.0135719] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 07/24/2015] [Indexed: 02/05/2023] Open
Abstract
Idiopathic pulmonary fibrosis (IPF), one of the most severe interstitial lung diseases, is a progressive fibrotic disorder of unknown etiology. However, there is growing appreciation for the role of viral infection in disease induction and/or progression. A small animal model of multi-organ fibrosis, which involves murine gammaherpesvirus (MHV68) infection of interferon gamma receptor deficient (IFNγR-/-) mice, has been utilized to model the association of gammaherpesvirus infections and lung fibrosis. Notably, several MHV68 mutants which fail to induce fibrosis have been identified. Our current study aimed to better define the role of the unique MHV68 gene, M1, in development of pulmonary fibrosis. We have previously shown that the M1 gene encodes a secreted protein which possesses superantigen-like function to drive the expansion and activation of Vβ4+ CD8+ T cells. Here we show that M1-dependent fibrosis is correlated with heightened levels of inflammation in the lung. We observe an M1-dependent cellular infiltrate of innate immune cells with most striking differences at 28 days-post infection. Furthermore, in the absence of M1 protein expression we observed reduced CD8+ T cells and MHV68 epitope specific CD8+ T cells to the lungs-despite equivalent levels of viral replication between M1 null and wild type MHV68. Notably, backcrossing the IFNγR-/- onto the Balb/c background, which has previously been shown to exhibit weak MHV68-driven Vβ4+ CD8+ T cell expansion, eliminated MHV68-induced fibrosis-further implicating the activated Vβ4+ CD8+ T cell population in the induction of fibrosis. We further addressed the role that CD8+ T cells play in the induction of fibrosis by depleting CD8+ T cells, which protected the mice from fibrotic disease. Taken together these findings are consistent with the hypothesized role of Vβ4+ CD8+ T cells as mediators of fibrotic disease in IFNγR-/- mice.
Collapse
Affiliation(s)
- Brigid M. O’Flaherty
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States of America
- Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Caline G. Matar
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States of America
- Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Brian S. Wakeman
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States of America
- Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA, United States of America
| | - AnaPatricia Garcia
- Division of Pathology, Yerkes National Primate Research Center, Emory University, Atlanta GA, United States of America
| | - Carol A. Wilke
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Michigan, Ann Arbor, MI, United States of America
| | - Cynthia L. Courtney
- Division of Pathology, Yerkes National Primate Research Center, Emory University, Atlanta GA, United States of America
| | - Bethany B. Moore
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Michigan, Ann Arbor, MI, United States of America
| | - Samuel H. Speck
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States of America
- Emory Vaccine Center, Emory University School of Medicine, Atlanta, GA, United States of America
| |
Collapse
|
5
|
Gammaherpesvirus small noncoding RNAs are bifunctional elements that regulate infection and contribute to virulence in vivo. mBio 2015; 6:e01670-14. [PMID: 25691585 PMCID: PMC4337559 DOI: 10.1128/mbio.01670-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Many viruses express noncoding RNAs (ncRNAs). The gammaherpesviruses (γHVs), including Epstein-Barr virus, Kaposi’s sarcoma-associated herpesvirus, and murine γHV68, each contain multiple ncRNA genes, including microRNAs (miRNAs). While these ncRNAs can regulate multiple host and viral processes in vitro, the genetic contribution of these RNAs to infection and pathogenesis remains largely unknown. To study the functional contribution of these RNAs to γHV infection, we have used γHV68, a small-animal model of γHV pathogenesis. γHV68 encodes eight small hybrid ncRNAs that contain both tRNA-like elements and functional miRNAs. These genes are transcribed by RNA polymerase III and are referred to as the γHV68 TMERs (tRNA-miRNA-encoded RNAs). To determine the total concerted genetic contribution of these ncRNAs to γHV acute infection and pathogenesis, we generated and characterized a recombinant γHV68 strain devoid of all eight TMERs. TMER-deficient γHV68 has wild-type levels of lytic replication in vitro and normal establishment of latency in B cells early following acute infection in vivo. In contrast, during acute infection of immunodeficient mice, TMER-deficient γHV68 has reduced virulence in a model of viral pneumonia, despite having an enhanced frequency of virus-infected cells. Strikingly, expression of a single viral tRNA-like molecule, in the absence of all other virus-encoded TMERs and miRNAs, reverses both attenuation in virulence and enhanced frequency of infected cells. These data show that γHV ncRNAs play critical roles in acute infection and virulence in immunocompromised hosts and identify these RNAs as a new potential target to modulate γHV-induced infection and pathogenesis. The gammaherpesviruses (γHVs) are a subfamily of viruses associated with chronic inflammatory diseases and cancer, particularly in immunocompromised individuals. These viruses uniformly encode multiple types of noncoding RNAs (ncRNAs) that are not translated into proteins. It remains unclear how virus-expressed ncRNAs influence the course and outcome of infection in vivo. Here, we generated a mouse γHV that lacks the expression of multiple ncRNAs. Notably, this mutant virus is critically impaired in the ability to cause disease in immunocompromised hosts yet shows a paradoxical increase in infected cells early during infection in these hosts. While the original mouse virus encodes multiple ncRNAs, the expression of a single domain of one ncRNA can partially reverse the defects of the mutant virus. These studies demonstrate that γHV ncRNAs can directly contribute to virus-induced disease in vivo and that these RNAs may be multifunctional, allowing the opportunity to specifically interfere with different functional domains of these RNAs.
Collapse
|
6
|
Lindquester GJ, Greer KA, Stewart JP, Sample JT. Epstein-Barr virus IL-10 gene expression by a recombinant murine gammaherpesvirus in vivo enhances acute pathogenicity but does not affect latency or reactivation. HERPESVIRIDAE 2014; 5:1. [PMID: 25324959 PMCID: PMC4199788 DOI: 10.1186/2042-4280-5-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 09/21/2014] [Indexed: 11/10/2022]
Abstract
Background Many viral genes affect cytokine function within infected hosts, with interleukin 10 (IL-10) as a commonly targeted mediator. Epstein-Barr virus (EBV) encodes an IL-10 homologue (vIL-10) expressed during productive (lytic) infection and induces expression of cellular IL-10 (cIL-10) during latency. This study explored the role of vIL-10 in a murine gammaherpesvirus (MHV) model of viral infection. Methods The EBV vIL-10 gene was inserted into MHV-76, a strain which lacks the ability to induce cIL-10, by recombination in transfected mouse cells. Mice were infected intranasally with the recombinant, vIL-10-containing MHV-76 or control virus strains and assayed at various days post infection for lung virus titer, spleen cell number, percentage of latently infected spleen cells and ability to reactivate virus from spleen cells. Results Recombinant murine gammaherpesvirus expressing EBV vIL-10 rose to significantly higher titers in lungs and promoted an increase in spleen cell number in infected mice in comparison to MHV strains lacking the vIL-10 gene. However, vIL-10 expression did not alter the quantity of latent virus in the spleen or its ability to reactivate. Conclusions In this mouse model of gammaherpesvirus infection, EBV vIL-10 appears to influence acute-phase pathogenicity. Given that EBV and MHV wild-type strains contain other genes that induce cIL-10 expression in latency (e.g. LMP-1 and M2, respectively), vIL-10 may have evolved to serve the specific role in acute infection of enlarging the permissive host cell population, perhaps to facilitate initial survival and dissemination of viral-infected cells.
Collapse
Affiliation(s)
| | | | - James P Stewart
- Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool L3 5RF, UK
| | - Jeffery T Sample
- Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, TN 38105, USA ; Current Address: Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| |
Collapse
|
7
|
The murine gammaherpesvirus immediate-early Rta synergizes with IRF4, targeting expression of the viral M1 superantigen to plasma cells. PLoS Pathog 2014; 10:e1004302. [PMID: 25101696 PMCID: PMC4125235 DOI: 10.1371/journal.ppat.1004302] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 06/29/2014] [Indexed: 11/19/2022] Open
Abstract
MHV68 is a murine gammaherpesvirus that infects laboratory mice and thus provides a tractable small animal model for characterizing critical aspects of gammaherpesvirus pathogenesis. Having evolved with their natural host, herpesviruses encode numerous gene products that are involved in modulating host immune responses to facilitate the establishment and maintenance of lifelong chronic infection. One such protein, MHV68 M1, is a secreted protein that has no known homologs, but has been shown to play a critical role in controlling virus reactivation from latently infected macrophages. We have previous demonstrated that M1 drives the activation and expansion of Vβ4+ CD8+ T cells, which are thought to be involved in controlling MHV68 reactivation through the secretion of interferon gamma. The mechanism of action and regulation of M1 expression are poorly understood. To gain insights into the function of M1, we set out to evaluate the site of expression and transcriptional regulation of the M1 gene. Here, using a recombinant virus expressing a fluorescent protein driven by the M1 gene promoter, we identify plasma cells as the major cell type expressing M1 at the peak of infection in the spleen. In addition, we show that M1 gene transcription is regulated by both the essential viral immediate-early transcriptional activator Rta and cellular interferon regulatory factor 4 (IRF4), which together potently synergize to drive M1 gene expression. Finally, we show that IRF4, a cellular transcription factor essential for plasma cell differentiation, can directly interact with Rta. The latter observation raises the possibility that the interaction of Rta and IRF4 may be involved in regulating a number of viral and cellular genes during MHV68 reactivation linked to plasma cell differentiation. Through coevolution with their hosts, gammaherpesviruses have acquired unique genes that aid in infection of a particular host. Here we study the regulation of the MHV68 M1 gene, which encodes a protein that modulates the host immune response. Using a strategy that allowed us to identify MHV68 infected cells in mice, we have determined that M1 expression is largely limited to the antibody producing plasma cells. In addition, we show that M1 gene expression is regulated by both cellular and viral factors, which allow the virus to fine-tune gene expression in response to environmental signals. These findings provide insights into M1 function through a better understanding of how M1 expression is regulated.
Collapse
|
8
|
Decalf J, Godinho-Silva C, Fontinha D, Marques S, Simas JP. Establishment of murine gammaherpesvirus latency in B cells is not a stochastic event. PLoS Pathog 2014; 10:e1004269. [PMID: 25079788 PMCID: PMC4117635 DOI: 10.1371/journal.ppat.1004269] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 06/10/2014] [Indexed: 12/21/2022] Open
Abstract
Murid γ-herpesvirus-4 (MuHV-4) promotes polyclonal B cell activation and establishes latency in memory B cells via unclear mechanisms. We aimed at exploring whether B cell receptor specificity plays a role in B cell susceptibility to viral latency and how this is related to B cell activation. We first observed that MuHV-4-specific B cells represent a minority of the latent population, and to better understand the influence of the virus on non-MuHV-4 specific B cells we used the SWHEL mouse model, which produce hen egg lysozyme (HEL)-specific B cells. By tracking HEL+ and HEL− B cells, we showed that in vivo latency was restricted to HEL− B cells while the two populations were equally sensitive to the virus in vitro. Moreover, MuHV-4 induced two waves of B cell activation. While the first wave was characterized by a general B cell activation, as shown by HEL+ and HEL− B cells expansion and upregulation of CD69 expression, the second wave was restricted to the HEL− population, which acquired germinal center (GC) and plasma cell phenotypes. Antigenic stimulation of HEL+ B cells led to the development of HEL+ GC B cells where latent infection remained undetectable, indicating that MuHV-4 does not benefit from acute B cell responses to establish latency in non-virus specific B cells but relies on other mechanisms of the humoral response. These data support a model in which the establishment of latency in B cells by γ-herpesviruses is not stochastic in terms of BCR specificity and is tightly linked to the formation of GCs. Murid γ-herpesvirus-4 (MuHV-4) is a good model to study infectious mononucleosis in mice, in which the virus ultimately establishes life-long latency in B cells. Whereas several viral proteins have been shown to modulate B cell behavior, in the present study we aimed at clarifying the parameters that dictate the establishment of viral latency from the B cell perspective. Indeed, the B cell repertoire is highly diverse and it remains unknown whether latency takes place randomly in B cells. To study this question, we isolated latently infected B cells in which we observed a low frequency of virus-specific B cells, suggesting that viral latency is not restricted to this population. To better understand MuHV-4 influence on non-virus specific B cells, we then followed the fate of B cells specific for a foreign antigen, hen egg lysozyme (HEL). While in vitro experiments showed that HEL-specific B cells could be acutely infected by MuHV-4, these cells were resistant to MuHV-4 latent infection in vivo. These results suggest that while establishment of γ-herpesvirus latency is not restricted to virus-specific B cells, it does not take place randomly in B cells and relies on mechanisms that remain to be identified.
Collapse
Affiliation(s)
- Jérémie Decalf
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Cristina Godinho-Silva
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Diana Fontinha
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Sofia Marques
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - J. Pedro Simas
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- * E-mail:
| |
Collapse
|
9
|
Correia B, Cerqueira SA, Beauchemin C, Pires de Miranda M, Li S, Ponnusamy R, Rodrigues L, Schneider TR, Carrondo MA, Kaye KM, Simas JP, McVey CE. Crystal structure of the gamma-2 herpesvirus LANA DNA binding domain identifies charged surface residues which impact viral latency. PLoS Pathog 2013; 9:e1003673. [PMID: 24146618 PMCID: PMC3798461 DOI: 10.1371/journal.ppat.1003673] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/16/2013] [Indexed: 01/12/2023] Open
Abstract
Latency-associated nuclear antigen (LANA) mediates γ2-herpesvirus genome persistence and regulates transcription. We describe the crystal structure of the murine gammaherpesvirus-68 LANA C-terminal domain at 2.2 Å resolution. The structure reveals an alpha-beta fold that assembles as a dimer, reminiscent of Epstein-Barr virus EBNA1. A predicted DNA binding surface is present and opposite this interface is a positive electrostatic patch. Targeted DNA recognition substitutions eliminated DNA binding, while certain charged patch mutations reduced bromodomain protein, BRD4, binding. Virus containing LANA abolished for DNA binding was incapable of viable latent infection in mice. Virus with mutations at the charged patch periphery exhibited substantial deficiency in expansion of latent infection, while central region substitutions had little effect. This deficiency was independent of BRD4. These results elucidate the LANA DNA binding domain structure and reveal a unique charged region that exerts a critical role in viral latent infection, likely acting through a host cell protein(s). Herpesviruses establish life-long latent infections. During latency, gammaherpesviruses, such as Kaposi's sarcoma-associated herpesvirus (KSHV), persist as multicopy, circularized genomes in the cell nucleus and express a small subset of viral genes. KSHV latency-associated nuclear antigen (LANA) is the predominant gene expressed during latent infection. C-terminal LANA binds KSHV terminal repeat (TR) DNA to mediate DNA replication. TR DNA binding also allows tethering of the viral genome to mitotic chromosomes to mediate DNA segregation to daughter nuclei. We describe here the crystal structure of the murine gammaherpesvirus 68 LANA DNA binding domain, which is homologous to that of KSHV LANA. The structure revealed a dimer and we identified residues involved in the interaction with viral DNA. Mutation of these residues abolished DNA binding and viable latency establishment in a mouse model of infection. We also identified a positively charged patch on the dimer surface opposite to the DNA binding region and found this patch exerts an important role in the virus's ability to expand latent infection in vivo. This work elucidates the structure of the LANA DNA binding domain and identifies a novel surface feature that is critical for viral latent infection, likely by acting through a host cell protein.
Collapse
Affiliation(s)
- Bruno Correia
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Sofia A. Cerqueira
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Chantal Beauchemin
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marta Pires de Miranda
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Shijun Li
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Rajesh Ponnusamy
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Lénia Rodrigues
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | | | - Maria A. Carrondo
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail: (MAC); (KMK); (JPS); (CEM)
| | - Kenneth M. Kaye
- Departments of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (MAC); (KMK); (JPS); (CEM)
| | - J. Pedro Simas
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (MAC); (KMK); (JPS); (CEM)
| | - Colin E. McVey
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail: (MAC); (KMK); (JPS); (CEM)
| |
Collapse
|
10
|
Systemic and local infection routes govern different cellular dissemination pathways during gammaherpesvirus infection in vivo. J Virol 2013; 87:4596-608. [PMID: 23408606 DOI: 10.1128/jvi.03135-12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Human gammaherpesviruses cause morbidity and mortality associated with infection and transformation of lymphoid and endothelial cells. Knowledge of cell types involved in virus dissemination from primary virus entry to virus latency is fundamental for the understanding of gammaherpesvirus pathogenesis. However, the inability to directly trace cell types with respect to virus dissemination pathways has prevented definitive conclusions regarding the relative contribution of individual cell types. Here, we describe that the route of infection affects gammaherpesvirus dissemination pathways. We constructed a recombinant murine gammaherpesvirus 68 (MHV-68) variant harboring a cassette which switches fluorescent markers in a Cre-dependent manner. Since the recombinant virus which was constructed on the wild-type background was attenuated, in this study we used an M1-deleted version, which infected mice with normal kinetics. Infection of Cre-transgenic mice with this convertible virus was used to estimate the quantitative contribution of defined cell types to virus productivity and dissemination during the acute phase of MHV-68 infection. In systemic infection, we found splenic vascular endothelial cells (EC) among the first and main cells to produce virus. After local infection, the contribution of EC to splenic virus production did not represent such early kinetics. However, at later time points, B cell-derived viruses dominated splenic productivity independently of systemic or local infection. Systemic versus local infection also governed the cell types involved in loading peritoneal exudate cells, leading to latency in F4/80- and CD11b-positive target cells. Systemic infection supported EC-driven dissemination, whereas local infection supported B cell-driven dissemination.
Collapse
|
11
|
The absence of M1 leads to increased establishment of murine gammaherpesvirus 68 latency in IgD-negative B cells. J Virol 2013; 87:3597-604. [PMID: 23302876 DOI: 10.1128/jvi.01953-12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The secreted M1 protein of murine gammaherpesvirus 68 (MHV68) promotes effector Vβ4(+) CD8(+) T cell expansion to impact virus control and immune-mediated pathologies in C57BL/6 mice, but not BALB/c mice. We report a striking increase in the number of genome-positive, IgD(-) B cells during chronic infection of both mouse strains. This suggests a novel role for M1 in influencing long-term maintenance in a major latency reservoir irrespective of the degree of Vβ4(+) CD8(+) T cell expansion.
Collapse
|
12
|
MHV-68 producing mIFNα1 is severely attenuated in vivo and effectively protects mice against challenge with wt MHV-68. Vaccine 2011; 29:3935-44. [DOI: 10.1016/j.vaccine.2011.03.092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 03/03/2011] [Accepted: 03/25/2011] [Indexed: 11/22/2022]
|
13
|
Murine gammaherpesvirus 68 infection of gamma interferon-deficient mice on a BALB/c background results in acute lethal pneumonia that is dependent on specific viral genes. J Virol 2009; 83:11397-401. [PMID: 19710134 DOI: 10.1128/jvi.00989-09] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gamma interferon (IFN-gamma) is critical for the control of chronic infection with murine gammaherpesvirus 68 (gammaHV68). Current data indicate that IFN-gamma has a lesser role in the control of acute replication of gammaHV68. Here, we show that IFN-gamma-deficient mice on the BALB/c genetic background poorly control acute viral replication and succumb to early death by acute pneumonia. Notably, this acute, lethal pneumonia was dependent not only on the viral dose, but also on specific viral genes including the viral cyclin gene, previously identified to be important in promoting optimal chronic infection and reactivation from latency.
Collapse
|
14
|
Epstein-Barr virus colonization of tonsillar and peripheral blood B-cell subsets in primary infection and persistence. Blood 2009; 113:6372-81. [DOI: 10.1182/blood-2008-08-175828] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
AbstractEpstein-Barr virus (EBV) persists in the immune host by preferentially colonizing the isotype-switched (IgD−CD27+) memory B-cell pool. In one scenario, this is achieved through virus infection of naive (IgD+CD27−) B cells and their differentiation into memory via germinal center (GC) transit; in another, EBV avoids GC transit and infects memory B cells directly. We report 2 findings consistent with this latter view. First, we examined circulating non–isotype-switched (IgD+CD27+) memory cells, a population that much evidence suggests is GC-independent in origin. Whereas isotype-switched memory had the highest viral loads by quantitative polymerase chain reaction, EBV was detectable in the nonswitched memory pool both in infectious mononucleosis (IM) patients undergoing primary infection and in most long-term virus carriers. Second, we examined colonization by EBV of B-cell subsets sorted from a unique collection of IM tonsillar cell suspensions. Here viral loads were concentrated in B cells with the CD38 marker of GC origin but lacking other GC markers CD10 and CD77. These findings, supported by histologic evidence, suggest that EBV infection in IM tonsils involves extrafollicular B cells expressing CD38 as an activation antigen and not as a marker of ectopic GC activity.
Collapse
|
15
|
Termination of NF-kappaB activity through a gammaherpesvirus protein that assembles an EC5S ubiquitin-ligase. EMBO J 2009; 28:1283-95. [PMID: 19322197 PMCID: PMC2664658 DOI: 10.1038/emboj.2009.74] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 03/03/2009] [Indexed: 12/11/2022] Open
Abstract
Host colonisation by lymphotropic gammaherpesviruses depends critically on the expansion of viral genomes in germinal centre (GC) B cells. Yet, host and virus molecular mechanisms involved in driving such proliferation remain largely unknown. Here, we show that the ORF73 protein encoded by the murid herpesvirus-4 (MuHV-4) inhibits host nuclear factor-kappa B (NF-κB) transcriptional activity through poly-ubiquitination and subsequent proteasomal-dependent nuclear degradation of the NF-κB family member p65/RelA. The mechanism involves the assembly of an ElonginC/Cullin5/SOCS (suppressors of cytokine signalling)-like complex, mediated by an unconventional viral SOCS-box motif present in ORF73. Functional deletion of this SOCS-box motif ablated NF-κB inhibitory effect of ORF73, suppressed MuHV-4 expansion in GC B cells and prevented MuHV-4 persistent infection in mice. These findings demonstrate that viral inhibition of NF-κB activity in latently infected GC centroblasts is critical for the establishment of a gammaherpesvirus persistent infection, underscoring the physiological importance of proteasomal degradation of RelA/NF-κB as a regulatory mechanism of this signalling pathway.
Collapse
|
16
|
He S, Yang Z, Skogerbo G, Ren F, Cui H, Zhao H, Chen R, Zhao Y. The properties and functions of virus encoded microRNA, siRNA, and other small noncoding RNAs. Crit Rev Microbiol 2008; 34:175-88. [PMID: 18972284 DOI: 10.1080/10408410802482008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
microRNAs (miRNAs) represent a class of noncoding RNA species, believed to be regulating gene expression by binding to complementary sites in the 3'UTRs of target mRNAs. They play important regulatory roles in various metabolic pathways in most eukaryotes. The recent discovery of virus encoded miRNAs suggests that viruses may be using them to regulate host and viral gene expression. Another class of closely related small interfering RNAs (siRNAs) also has been found within the HIV-1 genome and shown to be exerting a limited impact on virus reproduction. Additionally, an additional type of viral noncoding RNAs named small noncoding RNAs (sncRNAs) ranging from a few tens to a few hundred nucleotides in length, has also been identified. sncRNAs have a wide phylogenesis and high levels of expression, suggesting they may play an important roles in different species. Here we discuss the genomic organization, expression, conservation as well as potential function of virally encoded miRNA, siRNA, and sncRNAs.
Collapse
Affiliation(s)
- Shunmin He
- Department of Liver Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Science, CAMS & PUMC, Chinese Academy of Science, Beijing, China
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Marques S, Alenquer M, Stevenson PG, Simas JP. A single CD8+ T cell epitope sets the long-term latent load of a murid herpesvirus. PLoS Pathog 2008; 4:e1000177. [PMID: 18846211 PMCID: PMC2556087 DOI: 10.1371/journal.ppat.1000177] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Accepted: 09/15/2008] [Indexed: 12/29/2022] Open
Abstract
The pathogenesis of persistent viral infections depends critically on long-term viral loads. Yet what determines these loads is largely unknown. Here, we show that a single CD8+ T cell epitope sets the long-term latent load of a lymphotropic gamma-herpesvirus, Murid herpesvirus-4 (MuHV-4). The MuHV-4 M2 latency gene contains an H2-Kd -restricted T cell epitope, and wild-type but not M2− MuHV-4 was limited to very low level persistence in H2d mice. Mutating the epitope anchor residues increased viral loads and re-introducing the epitope reduced them again. Like the Kaposi's sarcoma–associated herpesvirus K1, M2 shows a high frequency of non-synonymous mutations, suggesting that it has been selected for epitope loss. In vivo competition experiments demonstrated directly that epitope presentation has a major impact on viral fitness. Thus, host MHC class I and viral epitope expression interact to set the long-term virus load. Persistent viruses present a major challenge to the immune response. Gamma-herpesviruses are a prime example, and the archetypal family member, Epstein-Barr virus (EBV), has been studied for many years. A major unanswered question with EBV is why long-term virus loads—a key pathogenesis outcome—vary so widely between individuals. As most EBV studies are necessarily descriptive, the murid gamma-herpesvirus MuHV-4 provides an important focus of pathogenesis research. Here, we used MuHV-4 to address what determines long-term gamma-herpesvirus loads. We find a major role for a single MHC class I–restricted latency epitope. This reflects that latency-associated viral immune evasion and transcriptional silencing create a unique setting, in which the pool of possible epitopes is small enough for epitope loss to have a significant impact on viral fitness. Our data suggest that polymorphisms in viral latency genes and in host HLA class I together determine long-term viral loads.
Collapse
Affiliation(s)
- Sofia Marques
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Marta Alenquer
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Philip G. Stevenson
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - J. Pedro Simas
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- * E-mail:
| |
Collapse
|
18
|
Evans AG, Moser JM, Krug LT, Pozharskaya V, Mora AL, Speck SH. A gammaherpesvirus-secreted activator of Vbeta4+ CD8+ T cells regulates chronic infection and immunopathology. J Exp Med 2008; 205:669-84. [PMID: 18332178 PMCID: PMC2275388 DOI: 10.1084/jem.20071135] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Accepted: 02/07/2008] [Indexed: 11/23/2022] Open
Abstract
Little is known about herpesvirus modulation of T cell activation in latently infected individuals or the implications of such for chronic immune disorders. Murine gammaherpesvirus 68 (MHV68) elicits persistent activation of CD8(+) T cells bearing a Vbeta4(+) T cell receptor (TCR) by a completely unknown mechanism. We show that a novel MHV68 protein encoded by the M1 gene is responsible for Vbeta4(+) CD8(+) T cell stimulation in a manner reminiscent of a viral superantigen. During infection, M1 expression induces a Vbeta4(+) effector T cell response that resists functional exhaustion and appears to suppress virus reactivation from peritoneal cells by means of long-term interferon-gamma (IFNgamma) production. Mice lacking an IFNgamma receptor (IFNgammaR(-/-)) fail to control MHV68 replication, and Vbeta4(+) and CD8(+) T cell activation by M1 instead contributes to severe inflammation and multiorgan fibrotic disease. Thus, M1 manipulates the host CD8(+) T cell response in a manner that facilitates latent infection in an immunocompetent setting, but promotes disease during a dysregulated immune response. Identification of a viral pathogenecity determinant with superantigen-like activity for CD8(+) T cells broadens the known repertoire of viral immunomodulatory molecules, and its function illustrates the delicate balance achieved between persistent viruses and the host immune response.
Collapse
Affiliation(s)
- Andrew G Evans
- Emory Vaccine Center, Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | | | | | | | | | | |
Collapse
|
19
|
Comparison of pathogenic properties of the murid gammaherpesvirus (MuHV 4) strains: a role for immunomodulatory proteins encoded by the left (5′-)end of the genome. Open Life Sci 2008. [DOI: 10.2478/s11535-008-0002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThe murid herpesvirus 4 (MuHV 4) species encompasses 7 isolates, out of which at least two (MHV-68, MHV-72) became in vitro propagated laboratory strains. Following intranasal inoculation, MuHV 4 induces an acute infectious mononucleosis-like syndrome with elevated levels of peripheral blood leukocytes, shifts in the relative proportion of lymphocytes along with the appearance of atypical mononuclear cells. At least two isolates exhibited spontaneous deletions at the left hand (5′-end) of their genome, resulting in the absence of M1, M2, M3 genes (strain MHV-72) and also of the M4 gene (strain MHV-76). Based on DNA sequence amplifications only, another two isolates (MHV-Šum and MHV-60) were shown to possess similar deletions of varying length. During latency (until 24 months post-infection), the mice infected with any MuHV 4 isolate (except MHV-76) developed lymphoproliferative disorders. The lack of tumor formation in MHV-76 infected mice was associated with persistent virus production at late post-infection intervals. In addition to careful analysis of spontaneously occurring 5′-end genome defects, our knowledge of the function of 5′-end genes relies on the behaviour of mutants with corresponding deletions and/or insertions. While M2 and M3 genes encode immune evasion proteins, M4 codes for a soluble glycopeptide acting as immunomodulator and/or immunostimulator.
Collapse
|
20
|
Pires de Miranda M, Alenquer M, Marques S, Rodrigues L, Lopes F, Bustelo XR, Simas JP. The Gammaherpesvirus m2 protein manipulates the Fyn/Vav pathway through a multidocking mechanism of assembly. PLoS One 2008; 3:e1654. [PMID: 18301737 PMCID: PMC2244710 DOI: 10.1371/journal.pone.0001654] [Citation(s) in RCA: 27] [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: 11/05/2007] [Accepted: 01/28/2008] [Indexed: 12/14/2022] Open
Abstract
To establish latent infections in B-cells, gammaherpesviruses express proteins in the infected B-cells of the host that spuriously activate signalling pathways located downstream of the B-cell receptor. One such protein is M2, a murine gammaherpesvirus 68-encoded molecule that activates the Vav1/Rac1 pathway via the formation of trimolecular complexes with Scr family members. Previous reports have shown that the formation of this heteromolecular complex involves interactions between a proline rich region of M2 and the Vav1 and Fyn SH3 domains. Here, we show that the optimal association of these proteins requires a second structural motif encompassing two tyrosine residues (Tyr120 and 129). These residues are inducibly phosphorylated by Fyn in non-hematopoietic cells and constitutively phosphorylated in B-cells. We also demonstrate that the phosphorylation of Tyr120 creates specific docking sites for the SH2 domains of both Vav1 and Fyn, a condition sine qua non for the optimal association of these two signalling proteins in vivo. Interestingly, signaling experiments indicate that the expression of M2 in B-cells promotes the tyrosine phosphorylation of Vav1 and additional signaling proteins, a biological process that requires the integrity of both the M2 phosphotyrosine and proline rich region motifs. By infecting mice with viruses mutated in the m2 locus, we show that the integrity of each of these two M2 docking motifs is essential for the early steps of murine gammaherpesvirus-68 latency. Taken together, these results indicate that the M2 phosphotyrosine motif and the previously described M2 proline rich region work in a concerted manner to manipulate the signaling machinery of the host B-cell.
Collapse
Affiliation(s)
- Marta Pires de Miranda
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Marta Alenquer
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Sofia Marques
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Lénia Rodrigues
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Filipa Lopes
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Xosé R. Bustelo
- Centro de Investigación del Cáncer and Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), University of Salamanca, Salamanca, Spain
- *E-mail: (XB); (JS)
| | - J. Pedro Simas
- Instituto de Microbiologia e Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- *E-mail: (XB); (JS)
| |
Collapse
|
21
|
Abstract
Bioinformatic and direct cloning approaches have led to the identification of over 100 novel miRNAs expressed in DNA viruses, although the function of the majority of these small regulatory RNA molecules is unclear. Recently, a number of reports have now identified potential targets of viral miRNAs, including cellular and viral genes as well as an ortholog of an important immuno-regulatory cellular miRNA. In this review, we will cover the identification and characterization of miRNAs expressed in the herpesvirus family and discuss the potential significance of their role in viral infection.
Collapse
|
22
|
Tibbetts SA, Suarez F, Steed AL, Simmons JA, Virgin HW. A gamma-herpesvirus deficient in replication establishes chronic infection in vivo and is impervious to restriction by adaptive immune cells. Virology 2006; 353:210-9. [PMID: 16797052 DOI: 10.1016/j.virol.2006.05.020] [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] [Received: 04/04/2006] [Revised: 05/04/2006] [Accepted: 05/16/2006] [Indexed: 02/08/2023]
Abstract
Chronic gamma-herpesvirus infection is a dynamic process involving latent infection, reactivation from latency, and low level persistent replication. The gamma-herpesviruses maintain latent infection in restricted subsets of hematopoietic cells as a result of an intricate balance between host factors that suppress infection and viral factors that facilitate evasion of the immune response. Immune effectors limit reactivation and subsequent replication events, and the adaptive immune response ultimately restricts infection to a level compatible with life-long infection. However, it has not been possible to determine whether the immune system constrains chronic infection by directly targeting latently infected cells in vivo due to the complex nature of chronic infection. To begin to address this issue, we generated a murine gamma-herpesvirus 68 (gammaHV68) deficient in its ability to replicate or undergo reactivation from latency via a mutation in the single-stranded DNA binding protein encoded by ORF6. Even in the absence of lytic replication, this virus established long-term infection in peritoneal cells of wild-type mice at levels identical to that of wild-type gammaHV68, and generated an immune response that was sufficient to protect against secondary challenge with wild-type gammaHV68. Nevertheless, the number of latently infected cells was not significantly altered in mice deficient in T cells or both T cells and B cells, demonstrating that the adaptive immune system is incapable of altering infection with a virus lacking the capacity for lytic replication and reactivation from latency. Thus, these data support the conclusion that latency is immunologically silent.
Collapse
Affiliation(s)
- Scott A Tibbetts
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid, Box 8118, St. Louis, MO 63110, USA.
| | | | | | | | | |
Collapse
|
23
|
Abstract
MicroRNAs (miRNAs) play a pivotal role in the regulation of genes involved in diverse processes such as development, differentiation, and cellular growth control. Recently, many viral-encoded miRNAs have been discovered, for the most part in viruses transcribed from double-stranded DNA genomes. As with their cellular counterparts, the functions of most viral-derived miRNAs are unknown; however, functions have been documented or proposed for viral miRNAs from three different viral families-herpesviruses, polyomaviruses, and retroviruses. Several virus-encoded miRNAs have unique aspects to their biogenesis, such as the polymerase that transcribes them or their location within the precursor transcript. Additionally, viral interactions with cellular miRNAs have also been identified, and these have substantially expanded our appreciation of miRNA functions.
Collapse
Affiliation(s)
- Christopher S Sullivan
- Howard Hughes Medical Institute, Department of Microbiology, University of California, San Francisco, CA 94143, USA
| | | |
Collapse
|
24
|
Rajćáni J, Kúdelová M. Murine herpesvirus pathogenesis: a model for the analysis of molecular mechanisms of human gamma herpesvirus infections. Acta Microbiol Immunol Hung 2005; 52:41-71. [PMID: 15957234 DOI: 10.1556/amicr.52.2005.1.2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Murine herpes virus (MHV), a natural pathogen originally isolated from free-living rodents, constitutes the most amenable animal model for human gamma herpesviruses. Based on DNA sequence homology, this virus was classified as Murid Herpesvirus 4 to subfamily Gammaherpesvirinae. Pilot studies in our laboratory, using mice inoculated by the intranasal route, showed that MHV infects macrophages, B lymphocytes, lung alveolar as well as endothelial cells. From the lungs the virus spreads via the bloodstream to spleen and bone marrow and via the lymphatics to the mediastinal lymph nodes. Similarly to other gamma herpesviruses, MHV established life-long latency maintained in host B lymphocytes and macrophages. An IM-like syndrome (per analogy to EBV) may develop during acute MHV infection, in which the atypical T/CD8+ lymphocytes eliminate viral DNA carrying B cells expressing the M2 latency associated protein. During latency, the MHV LANA (a KSHV LANA homologue) maintains the latent viral genome, assuring its copying and partition to new carrier cells in the course of division of the maternal cell. The nonproductive latency is turned onto virus replication by means of Rta protein. The chronic lymphoproliferative syndrome of unclear pathogenesis, which occurs in a certain part of latent MHV carriers, is related to the expression of gamma herpesvirus common latency-associated genes such as v-cyclin and/or to that of a virus-specific (M11/bcl-2) gene. This review attempts to summarize our knowledge concerning the function of MHV genes (either gamma herpesvirus common or MHV specific) related to immune evasion, latency and lymphoproliferation when highlighting the unsolved problems and/or controversial opinions.
Collapse
Affiliation(s)
- J Rajćáni
- Institute of Virology, Slovak Academy of Sciences, Dubravská 9, 84505 Bratislava, Slovak Republic.
| | | |
Collapse
|
25
|
Song MJ, Hwang S, Wong WH, Wu TT, Lee S, Liao HI, Sun R. Identification of viral genes essential for replication of murine gamma-herpesvirus 68 using signature-tagged mutagenesis. Proc Natl Acad Sci U S A 2005; 102:3805-10. [PMID: 15738413 PMCID: PMC553290 DOI: 10.1073/pnas.0404521102] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Gamma-herpesviruses, Epstein-Barr virus, and Kaposi's sarcoma-associated herpesvirus are important human pathogens, because they are involved in tumor development. Murine gamma-herpesvirus-68 (MHV-68 or gammaHV-68) has emerged as a small animal model system for the study of gamma-herpesvirus pathogenesis and host-virus interactions. To identify the genes required for viral replication in vitro and in vivo, we generated 1,152 mutants using signature-tagged transposon mutagenesis on an infectious bacterial artificial chromosome of MHV-68. Almost every ORF was mutated by random insertion. For each ORF, a mutant with an insertion proximal to the N terminus of each ORF was examined for the ability to grow in fibroblasts. Our results indicate that 41 genes are essential for in vitro growth, whereas 26 are nonessential and 6 attenuated. Replication-competent mutants were pooled to infect mice, which led to the discovery of ORF 54 being important for MHV-68 to replicate in the lung. This genetic analysis of a tumor-associated herpesvirus at the whole genome level validates signature-tagged transposon mutagenesis screening as an effective genetic system to identify important virulent genes in vivo and define interactions with the host immune system.
Collapse
Affiliation(s)
- Moon Jung Song
- Department of Microbiology, College of Medicine, Hallym University, Chuncheon 200-702, Republic of Korea
| | | | | | | | | | | | | |
Collapse
|
26
|
Simas JP, Marques S, Bridgeman A, Efstathiou S, Adler H. The M2 gene product of murine gammaherpesvirus 68 is required for efficient colonization of splenic follicles but is not necessary for expansion of latently infected germinal centre B cells. J Gen Virol 2004; 85:2789-2797. [PMID: 15448339 DOI: 10.1099/vir.0.80138-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Infection of mice with murine gammaherpesvirus 68 is characterized by a marked transient expansion of latently infected splenic germinal centre (GC) B cells, which is followed by lower levels of persistent infection in GC and memory B cells. Virus transcription within GC B cells is restricted to a number of latency-associated open reading frames, including M2. This gene encodes a structurally unique protein of unknown function, which has been shown to be essential for the transient peak of virus latency during the establishment of latent infection in the spleen. This study shows that upon infection of mice with M2-defective viruses, at 14 days post-infection during the establishment of latency in the spleen, there was a reduction in the number of latently infected follicles when compared with wild-type virus. However, the mean number of latently infected cells within each follicle was equivalent between wild-type and M2-defective viruses. Late in infection, disruption of M2 resulted in sustained and abnormally high levels of virus persistence in splenic GC B cells but not memory B cells. These data indicate that during the establishment of latency in the spleen, the M2 gene product is required for efficient colonization of splenic follicles but is dispensable for the expansion of latently infected GC B cells and that M2 might be a critical modulator of B-cell function.
Collapse
Affiliation(s)
- J Pedro Simas
- Laboratory of Microbiology, Faculty of Medicine, University of Lisbon, Portugal
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
| | - Sofia Marques
- Laboratory of Microbiology, Faculty of Medicine, University of Lisbon, Portugal
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
| | - Anne Bridgeman
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal
| | - Stacey Efstathiou
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Heiko Adler
- GSF-Research Center for Environment and Health, Institute of Molecular Immunology, Clinical Cooperation Group Hematopoietic Cell Transplantation, Munich, Germany
| |
Collapse
|
27
|
Dutia BM, Roy DJ, Ebrahimi B, Gangadharan B, Efstathiou S, Stewart JP, Nash AA. Identification of a region of the virus genome involved in murine gammaherpesvirus 68-induced splenic pathology. J Gen Virol 2004; 85:1393-1400. [PMID: 15166421 DOI: 10.1099/vir.0.79908-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Infection with the murine gammaherpesvirus MHV-68 has profound effects on splenic and mediastinal lymph node pathology in mice which lack the interferon-gamma receptor (IFN-gamma R(-/-)). In these mice MHV-68 infection causes fibrosis and loss of lymphocytes in the spleen and the mediastinal lymph node as well as interstitial pulmonary fibrosis and fibrotic changes in the liver. The changes are associated with transient elevated latent virus loads in the spleen. Four independent virus mutants with insertions and/or deletions in the left end of the genome fail to induce the pathological changes and establish latency at normal levels in the spleen. The data indicate that the pathology does not correlate with any of the known genes encoded within this region of the genome, genes M1-M4 and the eight vtRNAs. Northern analysis of mRNAs transcribed by wild-type and mutant viruses shows that at least two uncharacterized transcripts are encoded within this region. These transcripts are absent in the mutant viruses and are candidates for the virus genes responsible for the aberrant pathology in IFN-gamma R(-/-) mice.
Collapse
Affiliation(s)
- Bernadette M Dutia
- Laboratory for Clinical and Molecular Virology, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
| | - Douglas J Roy
- Laboratory for Clinical and Molecular Virology, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
| | - Bahram Ebrahimi
- Laboratory for Clinical and Molecular Virology, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
| | - Babunilayam Gangadharan
- Laboratory for Clinical and Molecular Virology, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
| | - Stacey Efstathiou
- Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - James P Stewart
- Laboratory for Clinical and Molecular Virology, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
| | - Anthony A Nash
- Laboratory for Clinical and Molecular Virology, Division of Veterinary Biomedical Sciences, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
| |
Collapse
|
28
|
May JS, Coleman HM, Smillie B, Efstathiou S, Stevenson PG. Forced lytic replication impairs host colonization by a latency-deficient mutant of murine gammaherpesvirus-68. J Gen Virol 2004; 85:137-146. [PMID: 14718628 DOI: 10.1099/vir.0.19599-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A regulated switch between latent and lytic gene expression is common to all known herpesviruses. However, the effects on host colonization of altering this switch are largely unknown. We deregulated the transcription of the gene encoding the major lytic transactivator of murine gammaherpesvirus-68, ORF50, by inserting a new and powerful promoter element in its 5' untranslated region. In vitro, the mutant virus (M50) transcribed ORF50 at a high level and showed more rapid lytic spread in permissive fibroblast cultures, but in vivo, the M50 virus showed a severe deficit in latency establishment, with no sign of the infectious mononucleosis-like illness normally associated with wild-type infection. Although a low level of M50 viral DNA was detectable by PCR in spleens, replication-competent virus could not be recovered beyond 10 days post-infection. The M50 virus was also attenuated in immunocompromised mice. Thus a gammaherpesvirus unable to shut off lytic cycle gene expression showed severely restricted host colonization.
Collapse
Affiliation(s)
- Janet S May
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Heather M Coleman
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Belinda Smillie
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Stacey Efstathiou
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Philip G Stevenson
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| |
Collapse
|
29
|
Fowler P, Marques S, Simas JP, Efstathiou S. ORF73 of murine herpesvirus-68 is critical for the establishment and maintenance of latency. J Gen Virol 2004; 84:3405-3416. [PMID: 14645921 DOI: 10.1099/vir.0.19594-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In vitro studies have established that the latency-associated nuclear antigen encoded by human Kaposi's sarcoma-associated herpesvirus and the related ORF73 gene product of herpesvirus saimiri interact with virus origins of replication to facilitate maintenance of episomal DNA. Such a function implies a critical role for ORF73 in the establishment and maintenance of latency in vivo. To determine the role of ORF73 in virus pathogenesis, the ORF73 gene product encoded by murine herpesvirus-68 (MHV-68) was disrupted by making an ORF73 deletion mutant, Delta73, and an independent ORF73 frameshift mutant, FS73. The effect of the mutations introduced in ORF73 on MHV-68 pathogenesis was analysed in vivo using a well-characterized murine model system. These studies have revealed that ORF73 is not required for efficient lytic replication either in vitro or in vivo. In contrast, a severe latency deficit is observed in splenocytes of animals infected with an ORF73 mutant, as assessed by infectious centre reactivation assay or by in situ hybridization detection of latent virus. Assessment of viral genome-positive cells in sorted splenocyte populations confirmed the absence of ORF73 mutant virus from splenic latency reservoirs, including germinal centre B cells. These data indicate a crucial role for ORF73 in the establishment of latency and for virus persistence in the host.
Collapse
Affiliation(s)
- Polly Fowler
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Sofia Marques
- Laboratory of Microbiology, Faculty of Medicine, University of Lisbon, 1649-028 Lisbon, Portugal
- Instituto Gulbenkian de Cieˆncia, 2780-156 Oeiras, Portugal
| | - J Pedro Simas
- Laboratory of Microbiology, Faculty of Medicine, University of Lisbon, 1649-028 Lisbon, Portugal
- Instituto Gulbenkian de Cieˆncia, 2780-156 Oeiras, Portugal
| | - Stacey Efstathiou
- Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| |
Collapse
|
30
|
Marques S, Efstathiou S, Smith KG, Haury M, Simas JP. Selective gene expression of latent murine gammaherpesvirus 68 in B lymphocytes. J Virol 2003; 77:7308-18. [PMID: 12805429 PMCID: PMC164786 DOI: 10.1128/jvi.77.13.7308-7318.2003] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Intranasal infection of mice with murine gammaherpesvirus 68 (MHV-68), a virus genetically related to the human pathogen Kaposi's sarcoma-associated herpesvirus, results in a persistent, latent infection in the spleen and other lymphoid organs. Here, we have determined the frequency of virus infection in splenic dendritic cells, macrophages, and several B-cell subpopulations, and we quantified cell type-dependent virus transcription patterns. The frequencies of virus genome positive cells were maximal at 14 days postinfection in all splenic cell populations analyzed. Marginal zone and germinal center B cells harbored the highest frequency of infection and the former population accounted for approximately half the total number of infected B cells. Analysis of virus transcription during the establishment of latency revealed that virus gene expression in B cells was restricted and dependent on the differentiation stage of the B cell. Notably, transcription of ORF73 was detected in germinal center B cells, a finding in agreement with the predicted latent genome maintenance function of ORF73 in dividing cells. At late times after infection, virus DNA could only be detected in newly formed and germinal center B cells, which suggests that B cells play a critical role in facilitating life-long latency.
Collapse
Affiliation(s)
- Sofia Marques
- Gulbenkian Institute for Science, 2780-156 Oeiras, Portugal
| | | | | | | | | |
Collapse
|
31
|
Adler H, Messerle M, Koszinowski UH. Cloning of herpesviral genomes as bacterial artificial chromosomes. Rev Med Virol 2003; 13:111-21. [PMID: 12627394 DOI: 10.1002/rmv.380] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Herpesviruses, which are important pathogens for both animals and humans, have large and complex genomes with a coding capacity for up to 225 open reading frames (ORFs). Due to the large genome size and the slow replication kinetics in vitro of some herpesviruses, mutagenesis of viral genes in the context of the viral genome by conventional recombination methods in cell culture has been difficult. Given that mutagenesis of viral genes is the basic strategy to investigate function, many of the herpesvirus ORFs could not be defined functionally. Recently, a completely new approach for the construction of herpesvirus mutants has been developed, based on cloning of the virus genome as a bacterial artificial chromosome (BAC) in E. coli. This technique allows the maintenance of viral genomes as a plasmid in E. coli and the reconstitution of viral progeny by transfection of the BAC plasmid into eukaryotic cells. Any genetic modification of the viral genome in E. coli using prokaryotic recombination proteins is possible, thereby allowing the generation of mutant viruses and facilitating the analysis of herpesvirus genomes cloned as infectious BACs. In this review, we describe the principle of cloning a viral genome as a BAC using murine gammaherpesvirus 68 (MHV-68), a mouse model for gammaherpesvirus infections, as an example.
Collapse
Affiliation(s)
- Heiko Adler
- GSF-Research Center for Environment and Health, Institute of Molecular Immunology, Clinical Cooperation Group Hematopoietic Cell Transplantation, Munich, Germany.
| | | | | |
Collapse
|
32
|
Ebrahimi B, Dutia BM, Roberts KL, Garcia-Ramirez JJ, Dickinson P, Stewart JP, Ghazal P, Roy DJ, Nash AA. Transcriptome profile of murine gammaherpesvirus-68 lytic infection. J Gen Virol 2003; 84:99-109. [PMID: 12533705 DOI: 10.1099/vir.0.18639-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The murine gammaherpesvirus-68 genome encodes 73 protein-coding open reading frames with extensive similarities to human gamma(2) herpesviruses, as well as unique genes and cellular homologues. We performed transcriptome analysis of stage-specific viral RNA during permissive infection using an oligonucleotide-based microarray. Using this approach, M4, K3, ORF38, ORF50, ORF57 and ORF73 were designated as immediate-early genes based on cycloheximide treatment. The microarray analysis also identified 10 transcripts with early expression kinetics, 32 transcripts with early-late expression kinetics and 29 transcripts with late expression kinetics. The latter group consisted mainly of structural proteins, and showed high expression levels relative to other viral transcripts. Moreover, we detected all eight tRNA-like transcripts in the presence of cycloheximide and phosphonoacetic acid. Lytic infection with MHV-68 also resulted in a significant reduction in the expression of cellular transcripts included in the DNA chip. This global approach to viral transcript analysis offers a powerful system for examining molecular transitions between lytic and latent virus infections associated with disease pathogenesis.
Collapse
Affiliation(s)
- Bahram Ebrahimi
- Laboratory for Clinical and Molecular Virology, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - Bernadette M Dutia
- Laboratory for Clinical and Molecular Virology, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - Kim L Roberts
- Laboratory for Clinical and Molecular Virology, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - Jose J Garcia-Ramirez
- Scottish Centre for Genomic Technology and Informatics, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - Paul Dickinson
- MRC Centre for Inflammation Research, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
- Scottish Centre for Genomic Technology and Informatics, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - James P Stewart
- Laboratory for Clinical and Molecular Virology, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - Peter Ghazal
- Scottish Centre for Genomic Technology and Informatics, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - Douglas J Roy
- Scottish Centre for Genomic Technology and Informatics, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| | - Anthony A Nash
- Laboratory for Clinical and Molecular Virology, The University of Edinburgh, Summerhall Square, Edinburgh EH9 1QH, UK
| |
Collapse
|
33
|
van Berkel V, Levine B, Kapadia SB, Goldman JE, Speck SH, Virgin HW. Critical role for a high-affinity chemokine-binding protein in gamma-herpesvirus-induced lethal meningitis. J Clin Invest 2002; 109:905-14. [PMID: 11927617 PMCID: PMC150927 DOI: 10.1172/jci14358] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Chemokines are involved in recruitment and activation of hematopoietic cells in sites of infection and inflammation. The M3 gene of the gamma-herpesvirus gammaHV68 encodes an abundant secreted protein that binds CC chemokines with high affinity. We report here that this gene is essential for efficient induction of lethal meningitis by gammaHV68. An M3 mutant gammaHV68 (gammaHV68-M3.stop) was 100-fold less virulent than wild-type or marker rescue control (gammaHV68-M3.MR) viruses after intracerebral inoculation. After intracerebral inoculation, gammaHV68-M3.stop grew to lower titers than gammaHV68 or gammaHV68-M3.MR in the brain but spread to and grew normally in the spleen and lung. Expression of several CC chemokines was significantly induced in the CNS by gammaHV68 infection. Consistent with M3 acting by blockade of CC chemokine action, gammaHV68 induced a neutrophilic meningeal inflammatory infiltrate, while gammaHV68-M3.stop induced an infiltrate in which lymphocytes and macrophages predominated. In contrast to the important role of M3 in lethal meningitis, M3 was not required for establishment or reactivation from latent infection or induction of chronic arteritis. These data suggest a role for chemokines in the protection of the nervous system from viral infection and that the M3 protein acts in a tissue-specific fashion during acute but not chronic gammaHV68 infection to limit CC chemokine-induced inflammatory responses.
Collapse
Affiliation(s)
- Victor van Berkel
- Departments of Pathology and Immunology and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | | | | | | | | |
Collapse
|
34
|
Bridgeman A, Stevenson PG, Simas JP, Efstathiou S. A secreted chemokine binding protein encoded by murine gammaherpesvirus-68 is necessary for the establishment of a normal latent load. J Exp Med 2001; 194:301-12. [PMID: 11489949 PMCID: PMC2193474 DOI: 10.1084/jem.194.3.301] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Herpesviruses encode a variety of proteins with the potential to disrupt chemokine signaling, and hence immune organization. However, little is known of how these might function in vivo. The B cell-tropic murine gammaherpesvirus-68 (MHV-68) is related to the Kaposi's sarcoma-associated herpesvirus (KSHV), but whereas KSHV expresses small chemokine homologues, MHV-68 encodes a broad spectrum chemokine binding protein (M3). Here we have analyzed the effect on viral pathogenesis of a targeted disruption of the M3 gene. After intranasal infection, an M3 deficiency had surprisingly little effect on lytic cycle replication in the respiratory tract or the initial spread of virus to lymphoid tissues. However, the amplification of latently infected B cells in the spleen that normally drives MHV-68-induced infectious mononucleosis failed to occur. Thus, there was a marked reduction in latent virus recoverable by in vitro reactivation, latency-associated viral tRNA transcripts detectable by in situ hybridization, total viral DNA load, and virus-driven B cell activation. In vivo CD8(+) T cell depletion largely reversed this deficiency, suggesting that the chemokine neutralization afforded by M3 may function to block effective CD8(+) T cell recruitment into lymphoid tissue during the expansion of latently infected B cell numbers. In the absence of M3, MHV-68 was unable to establish a normal latent load.
Collapse
Affiliation(s)
- Anne Bridgeman
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Philip G. Stevenson
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - J. Pedro Simas
- Gulbenkian Institute for Science, 2780-156 Lisbon, Portugal
- Abel Salazar Institute of Biomedical Sciences, University of Oporto, Oporto 4099-003, Portugal
| | - Stacey Efstathiou
- Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| |
Collapse
|
35
|
Adler H, Messerle M, Koszinowski UH. Virus reconstituted from infectious bacterial artificial chromosome (BAC)-cloned murine gammaherpesvirus 68 acquires wild-type properties in vivo only after excision of BAC vector sequences. J Virol 2001; 75:5692-6. [PMID: 11356978 PMCID: PMC114283 DOI: 10.1128/jvi.75.12.5692-5696.2001] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We studied the in vivo biological properties of viruses reconstituted from the genome of murine gammaherpesvirus 68 (MHV-68) cloned as an infectious bacterial artificial chromosome (BAC). Recombinant virus RgammaHV68A98.01, containing BAC vector sequences, is attenuated in vivo as determined by (i) viral titers in the lungs during the acute phase of infection, (ii) the extent of splenomegaly, and (iii) the number of latently infected spleen cells reactivating virus in an ex vivo reactivation assay. Since the BAC vector sequences were flanked by loxP sites, passaging the virus in fibroblasts expressing Cre recombinase resulted in the generation of recombinant virus RgammaHV68A98.02, with biological properties comparable to those of wild-type MHV-68. On the basis of these data we conclude (i) that excision of BAC vector sequences from cloned MHV-68 genomes is critical for reconstitution of the wild-type phenotypic properties of this virus and (ii) that the BAC-cloned MHV-68 genome is suitable for the construction of mutants and mutant libraries whose phenotypes can be reliably assessed in vivo.
Collapse
Affiliation(s)
- H Adler
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Lehrstuhl Virologie, Genzentrum, Ludwig-Maximilians-Universität München, D-81377 Munich, Germany.
| | | | | |
Collapse
|
36
|
Macrae AI, Dutia BM, Milligan S, Brownstein DG, Allen DJ, Mistrikova J, Davison AJ, Nash AA, Stewart JP. Analysis of a novel strain of murine gammaherpesvirus reveals a genomic locus important for acute pathogenesis. J Virol 2001; 75:5315-27. [PMID: 11333912 PMCID: PMC114936 DOI: 10.1128/jvi.75.11.5315-5327.2001] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection of mice by murine gammaherpesvirus 68 (MHV-68) is an excellent small-animal model of gammaherpesvirus pathogenesis in a natural host. We have carried out comparative studies of another herpesvirus, murine herpesvirus 76 (MHV-76), which was isolated at the same time as MHV-68 but from a different murid host, the yellow-necked mouse (Apodemus flavicollis). Molecular analyses revealed that the MHV-76 genome is essentially identical to that of MHV-68, except for deletion of 9,538 bp at the left end of the unique region. MHV-76 is therefore a deletion mutant that lacks four genes unique to MHV-68 (M1, M2, M3, and M4) as well as the eight viral tRNA-like genes. Replication of MHV-76 in cell culture was identical to that of MHV-68. However, following infection of mice, MHV-76 was cleared more rapidly from the lungs. In line with this, there was an increased inflammatory response in lungs with MHV-76. Splenomegaly was also significantly reduced following MHV-76 infection, and much less latent MHV-76 was detected in the spleen. Nevertheless, MHV-76 maintained long-term latency in the lungs and spleen. We utilized a cosmid containing the left end of the MHV-68 genome to reinsert the deleted sequence into MHV-76 by recombination in infected cells, and we isolated a rescuant virus designated MHV-76(cA8+)4 which was ostensibly genetically identical to MHV-68. The growth properties of the rescuant in infected mice were identical to those of MHV-68. These results demonstrate that genetic elements at the left end of the unique region of the MHV-68 genome play vital roles in host evasion and are critical to the development of splenic pathology.
Collapse
Affiliation(s)
- A I Macrae
- Laboratory for Clinical and Molecular Virology, The University of Edinburgh, Edinburgh EH9 1QH, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Rochford R, Lutzke ML, Alfinito RS, Clavo A, Cardin RD. Kinetics of murine gammaherpesvirus 68 gene expression following infection of murine cells in culture and in mice. J Virol 2001; 75:4955-63. [PMID: 11333874 PMCID: PMC114898 DOI: 10.1128/jvi.75.11.4955-4963.2001] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A model system to study the pathogenesis of gammaherpesvirus infections is the infection of mice with murine gammaherpesvirus 68 (MHV-68). To define the kinetics of infection, we developed an RNase protection assay to quantitate gene expression from lytic (K3, Rta, M8, DNA polymerase [DNA pol], and gB) and candidate latency (M2, M3, M9, M11, ORF73, and ORF74) genes. All candidate latency genes were expressed during lytic infection of 3T3 cells. Four kinetic classes of transcripts were observed following infection of 3T3 cells: immediate-early (K3, Rta, M8, and ORF73), early (DNA pol), early-late (M3, M11, and ORF74), and late (M2, M9, and gB). To assess the kinetics of viral gene expression in vivo, lungs, spleens, and mediastinal lymph nodes (MLN) were harvested from MHV-68-infected mice. All transcripts were expressed between 3 and 6 days postinfection (dpi) in the lungs. In the spleen, K3, M3, M8, and M9 transcripts were expressed between 10 and 16 dpi when latency is established. The K3, M3, M8, M9, and M11 transcripts were detected in the MLN from 2 through 16 dpi. This is the first demonstration of MHV-68 gene expression in the MLN. Importantly, our data showed that MHV-68 has different kinetics of gene expression at different sites of infection. Furthermore, we demonstrated that K3, a gene recently shown to encode a protein that downregulates major histocompatibility complex class I on the surface of cells, is expressed during latency, which argues for a role of K3 in immune evasion during latent infection.
Collapse
Affiliation(s)
- R Rochford
- Department of Epidemiology, University of Michigan, Ann Arbor, Michigan 48109, USA.
| | | | | | | | | |
Collapse
|
38
|
Nash AA, Dutia BM, Stewart JP, Davison AJ. Natural history of murine gamma-herpesvirus infection. Philos Trans R Soc Lond B Biol Sci 2001; 356:569-79. [PMID: 11313012 PMCID: PMC1088445 DOI: 10.1098/rstb.2000.0779] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Murine gamma-herpesvirus 68 (MHV-68) is a natural pathogen of small rodents and insectivores (mice, voles and shrews). The primary infection is characterized by virus replication in lung epithelial cells and the establishment of a latent infection in B lymphocytes. The virus is also observed to persist in lung epithelial cells, dendritic cells and macrophages. Splenomegaly is observed two weeks after infection, in which there is a CD4+ T-cell-mediated expansion of B and T cells in the spleen. At three weeks post-infection an infectious mononucleosis-like syndrome is observed involving a major expansion of Vbeta4+CD8+ T cells. Later in the course of persistent infection, ca. 10% of mice develop lymphoproliferative disease characterized as lymphomas of B-cell origin. The genome from MHV-68 strain g2.4 has been sequenced and contains ca. 73 genes, the majority of which are collinear and homologous to other gamma-herpesviruses. The genome includes cellular homologues for a complement-regulatory protein, Bcl-2, cyclin D and interleukin-8 receptor and a set of novel genes M1 to M4. The function of these genes in the context of latent infections, evasion of immune responses and virus-mediated pathologies is discussed. Both innate and adaptive immune responses play an active role in limiting virus infection. The absence of type I interferon (IFN) results in a lethal MHV-68 infection, emphasizing the central role of these cytokines at the initial stages of infection. In contrast, type II IFN is not essential for the recovery from infection in the lung, but a failure of type II IFN receptor signalling results in the atrophy of lymphoid tissue associated with virus persistence. Splenic atrophy appears to be the result of immunopathology, since in the absence of CD8+ T cells no pathology occurs. CD8+ T cells play a major role in recovery from the primary infection, and also in regulating latently infected cells expressing the M2 gene product. CD4+ T cells have a key role in surveillance against virus recurrences in the lung, in part mediated through 'help' in the genesis of neutralizing antibodies. In the absence of CD4+ T cells, virus-specific CD8+ T cells are able to control the primary infection in the respiratory tract, yet surprisingly the memory CD8+ T cells generated are unable to inhibit virus recurrences in the lung. This could be explained in part by the observations that this virus can downregulate major histocompatibility complex class I expression and also restrict inflammatory cell responses by producing a chemokine-binding protein (M3 gene product). MHV-68 provides an excellent model to explore methods for controlling gamma-herpesvirus infection through vaccination and chemotherapy. Vaccination with gp150 (a homologue of gp350 of Epstein-Barr virus) results in a reduction in splenomegaly and virus latency but does not block replication in the lung, nor the establishment of a latent infection. Even when lung virus infection is greatly reduced following the action of CD8+ T cells, induced via a prime-boost vaccination strategy, a latent infection is established. Potent antiviral compounds such as the nucleoside analogue 2'deoxy-5-ethyl-beta-4'-thiouridine, which disrupts virus replication in vivo, cannot inhibit the establishment of a latent infection. Clearly, devising strategies to interrupt the establishment of latent virus infections may well prove impossible with existing methods.
Collapse
Affiliation(s)
- A A Nash
- Laboratory for Clinical and Molecular Virology, Department of Veterinary Pathology, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK.
| | | | | | | |
Collapse
|
39
|
Dal Canto AJ, Virgin HW, Speck SH. Ongoing viral replication is required for gammaherpesvirus 68-induced vascular damage. J Virol 2000; 74:11304-10. [PMID: 11070030 PMCID: PMC113235 DOI: 10.1128/jvi.74.23.11304-11310.2000] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2000] [Accepted: 09/11/2000] [Indexed: 11/20/2022] Open
Abstract
The role of autoimmunity in large-vessel vasculitis in humans remains unclear. We have previously shown that infection of gamma interferon receptor knockout (IFN-gamma R(-/-)) mice with gammaherpesvirus 68 (gamma HV68) results in severe inflammation of the large elastic arteries that is pathologically similar to the lesions observed in Takayasu's arteritis, the nongranulomatous variant of temporal arteritis, and Kawasaki's disease (K. E. Weck et al., Nat. Med. 3:1346-1353, 1997). Here we define the mechanism of damage to the elastic arteries. We show that there is a persistent productive infection of the media of the large elastic vessels. In addition, we demonstrate that persistent virus replication is necessary for chronic arteritis, since antiviral therapy of mice with established disease resulted in increased survival, clearance of viral antigen from the media of the affected vessel, and dramatic amelioration of arteritic lesions. These data argue that ongoing virus replication, rather than autoimmunity, is the cause of gamma HV68-induced elastic arteritis.
Collapse
Affiliation(s)
- A J Dal Canto
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | | |
Collapse
|
40
|
Adler H, Messerle M, Wagner M, Koszinowski UH. Cloning and mutagenesis of the murine gammaherpesvirus 68 genome as an infectious bacterial artificial chromosome. J Virol 2000; 74:6964-74. [PMID: 10888635 PMCID: PMC112213 DOI: 10.1128/jvi.74.15.6964-6974.2000] [Citation(s) in RCA: 279] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gammaherpesviruses cause important infections of humans, in particular in immunocompromised patients. Recently, murine gammaherpesvirus 68 (MHV-68) infection of mice has been developed as a small animal model of gammaherpesvirus pathogenesis. Efficient generation of mutants of MHV-68 would significantly contribute to the understanding of viral gene functions in virus-host interaction, thereby further enhancing the potential of this model. To this end, we cloned the MHV-68 genome as a bacterial artificial chromosome (BAC) in Escherichia coli. During propagation in E. coli, spontaneous recombination events within the internal and terminal repeats of the cloned MHV-68 genome, affecting the copy number of the repeats, were occasionally observed. The gene for the green fluorescent protein was incorporated into the cloned BAC for identification of infected cells. BAC vector sequences were flanked by loxP sites to allow the excision of these sequences using recombinase Cre and to allow the generation of recombinant viruses with wild-type genome properties. Infectious virus was reconstituted from the BAC-cloned MHV-68. Growth of the BAC-derived virus in cell culture was indistinguishable from that of wild-type MHV-68. To assess the feasibility of mutagenesis of the cloned MHV-68 genome, a mutant virus with a deletion of open reading frame 4 was generated. Genetically modified MHV-68 can now be analyzed in functionally modified mouse strains to assess the role of gammaherpesvirus genes in virus-host interaction and pathogenesis.
Collapse
Affiliation(s)
- H Adler
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Lehrstuhl Virologie, Genzentrum, Ludwig-Maximilians-Universität München, D-81377 Munich, Germany
| | | | | | | |
Collapse
|
41
|
van Berkel V, Barrett J, Tiffany HL, Fremont DH, Murphy PM, McFadden G, Speck SH, Virgin HW IV. Identification of a gammaherpesvirus selective chemokine binding protein that inhibits chemokine action. J Virol 2000; 74:6741-7. [PMID: 10888612 PMCID: PMC112190 DOI: 10.1128/jvi.74.15.6741-6747.2000] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chemokines are involved in recruitment and activation of hematopoietic cells at sites of infection and inflammation. The M3 gene of gammaHV68, a gamma-2 herpesvirus that infects and establishes a lifelong latent infection and chronic vasculitis in mice, encodes an abundant secreted protein during productive infection. The M3 gene is located in a region of the genome that is transcribed during latency. We report here that the M3 protein is a high-affinity broad-spectrum chemokine scavenger. The M3 protein bound the CC chemokines human regulated upon activation of normal T-cell expressed and secreted (RANTES), murine macrophage inflammatory protein 1alpha (MIP-1alpha), and murine monocyte chemoattractant protein 1 (MCP-1), as well as the human CXC chemokine interleukin-8, the murine C chemokine lymphotactin, and the murine CX(3)C chemokine fractalkine with high affinity (K(d) = 1. 6 to 18.7 nM). M3 protein chemokine binding was selective, since the protein did not bind seven other CXC chemokines (K(d) > 1 microM). Furthermore, the M3 protein abolished calcium signaling in response to murine MIP-1alpha and murine MCP-1 and not to murine KC or human stromal cell-derived factor 1 (SDF-1), consistent with the binding data. The M3 protein was also capable of blocking the function of human CC and CXC chemokines, indicating the potential for therapeutic applications. Since the M3 protein lacks homology to known chemokines, chemokine receptors, or chemokine binding proteins, these studies suggest a novel herpesvirus mechanism of immune evasion.
Collapse
Affiliation(s)
- V van Berkel
- Center for Immunology and Departments of Pathology and Immunology and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Flaño E, Husain SM, Sample JT, Woodland DL, Blackman MA. Latent murine gamma-herpesvirus infection is established in activated B cells, dendritic cells, and macrophages. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:1074-81. [PMID: 10878386 DOI: 10.4049/jimmunol.165.2.1074] [Citation(s) in RCA: 256] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Intranasal infection of mice with the murine gamma-herpesvirus MHV-68 results in an acute lytic infection in the lung, followed by the establishment of lifelong latency. Development of an infectious mononucleosis-like syndrome correlates with the establishment of latency and is characterized by splenomegaly and the appearance of activated CD8+ T cells in the peripheral blood. Interestingly, a large population of activated CD8+ T cells in the peripheral blood expresses the V beta 4+ element in their TCR. In this report we show that MHV-68 latency in the spleen after intranasal infection is harbored in three APC types: B cells, macrophages, and dendritic cells. Surprisingly, since latency has not previously been described in dendritic cells, these cells harbored the highest frequency of latent virus. Among B cells, latency was preferentially associated with activated B cells expressing the phenotype of germinal center B cells, thus formally linking the previously reported association of latency gene expression and germinal centers to germinal center B cells. Germinal center formation, however, was not required for the establishment of latency. Significantly, although three cell types were latently infected, the ability to stimulate V beta 4+CD8+ T cell hybridomas was limited to latently infected, activated B cells.
Collapse
Affiliation(s)
- E Flaño
- Department of Immunology, Program in Viral Oncogenesis and Tumor Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | | | | | | | | |
Collapse
|
43
|
Parry CM, Simas JP, Smith VP, Stewart CA, Minson AC, Efstathiou S, Alcami A. A broad spectrum secreted chemokine binding protein encoded by a herpesvirus. J Exp Med 2000; 191:573-8. [PMID: 10662803 PMCID: PMC2195820 DOI: 10.1084/jem.191.3.573] [Citation(s) in RCA: 185] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/1999] [Accepted: 11/11/1999] [Indexed: 11/25/2022] Open
Abstract
Chemokines are a family of small proteins that interact with seven-transmembrane domain receptors and modulate the migration of immune cells into sites of inflammation and infection. The murine gammaherpesvirus 68 M3 gene encodes a secreted 44-kD protein with no sequence similarity to known chemokine receptors. We show that M3 binds a broad range of chemokines, including CC, CXC, C, and CX(3)C chemokines, but does not bind human B cell-specific nor mouse neutrophil-specific CXC chemokines. This herpesvirus chemokine binding protein (hvCKBP) blocks the interaction of chemokines with high-affinity cellular receptors and inhibits chemokine-induced elevation of intracellular calcium levels. hvCKBP is the first soluble chemokine receptor identified in herpesviruses; it represents a novel protein structure with the ability to bind all subfamilies of chemokines in solution and has potential therapeutic applications.
Collapse
Affiliation(s)
- Christopher M. Parry
- From the Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - J. Pedro Simas
- From the Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Vincent P. Smith
- From the Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - C. Andrew Stewart
- From the Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Anthony C. Minson
- From the Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Stacey Efstathiou
- From the Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| | - Antonio Alcami
- From the Division of Virology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom
| |
Collapse
|
44
|
Clambey ET, Virgin HW, Speck SH. Disruption of the murine gammaherpesvirus 68 M1 open reading frame leads to enhanced reactivation from latency. J Virol 2000; 74:1973-84. [PMID: 10644370 PMCID: PMC111675 DOI: 10.1128/jvi.74.4.1973-1984.2000] [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] [Indexed: 11/20/2022] Open
Abstract
Murine gammaherpesvirus 68 (gammaHV68, or MHV-68) is a genetically tractable, small animal model for the analysis of gammaherpesvirus pathogenesis. The gammaHV68 genome is colinear with the genomes of other sequence gammaherpesviruses, containing large blocks of conserved genes interspersed by a number of putative genes without clear homologs in the other gammaherpesviruses. One of these putative unique genes, the M1 open reading frame (ORF), exhibits sequence homology to a poxvirus serine protease inhibitor, SPI-1, as well as to another gammaHV68 gene, M3, which we have recently shown encodes an abundantly secreted chemokine binding protein. To assess the contribution of the M1 ORF to gammaHV68 pathogenesis, we have generated a recombinant gammaHV68 in which the M1 ORF has been disrupted through targeted insertion of a lacZ expression cassette (M1.LacZ). Although M1.LacZ replicated normally in tissue culture, it exhibited decreased splenic titers at days 4 and 9 postinfection in both immunocompetent and immunodeficient mice. Despite decreased levels of acute virus replication, M1.LacZ established a latent infection comparable to wild-type (wt) gammaHV68, but exhibited an approximately fivefold increase in efficiency of reactivation from latency. M1.LacZ also caused severe vasculitis of the great elastic arteries in gamma interferon receptor (IFN-gammaR)-deficient mice with a frequency comparable to wt gammaHV68, but did not cause the mortality or splenic pathology observed with wt gammaHV68 infection of IFN-gammaR-deficient mice. Restoration of M1 ORF sequences into M1.LacZ (M1 marker rescue, or M1.MR) demonstrated that M1.LacZ phenotypic alterations in growth in vivo and latency were not due to the presence of additional mutations located elsewhere in the M1. LacZ genome. Generation of a second M1 mutant virus containing a deletion at the 5' end of the M1 ORF (M1Delta511), but lacking the LacZ expression cassette, revealed the same latency phenotype observed with the M1.LacZ mutant. However, M1Delta511 was not attenuated for acute virus replication in the spleen. We conclude that (i) the induction of arteritis in gammaHV68-infected IFN-gammaR-deficient mice can occur in the absence of splenic pathology and mortality, (ii) replication during acute infection is not the primary determinant for the establishment of latent infection, and (iii) the M1 ORF, or a closely linked gene, encodes a gene product that functions to suppress virus reactivation.
Collapse
Affiliation(s)
- E T Clambey
- Center for Immunology and Departments of Pathology and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
| | | | | |
Collapse
|
45
|
Ensser A, Pfinder A, Müller-Fleckenstein I, Fleckenstein B. The URNA genes of herpesvirus saimiri (strain C488) are dispensable for transformation of human T cells in vitro. J Virol 1999; 73:10551-5. [PMID: 10559377 PMCID: PMC113114 DOI: 10.1128/jvi.73.12.10551-10555.1999] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The herpesvirus saimiri strain C488 genome contains five genes for small nuclear RNAs, termed herpesvirus saimiri URNAs (or HSURs). Using a cosmid-based approach, all HSURs were precisely deleted from the genome. The mutant virus replicated at levels that were similar to those of wild-type viruses in OMK cells. Although the HSURs are expressed in wild-type virus-transformed human T-cell lines, the deletion does not affect viral transformation in cell culture.
Collapse
Affiliation(s)
- A Ensser
- Institut für Klinische und Molekulare Virologie der Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | | | | | | |
Collapse
|
46
|
Shisler JL, Isaacs SN, Moss B. Vaccinia virus serpin-1 deletion mutant exhibits a host range defect characterized by low levels of intermediate and late mRNAs. Virology 1999; 262:298-311. [PMID: 10502509 DOI: 10.1006/viro.1999.9884] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Orthopoxviruses encode three serpin homologs-SPI-1, SPI-2 and SPI-3-of which SPI-2 has been well characterized as an inhibitor of ICE-like proteases. A rabbitpox virus SPI-1 deletion mutant exhibited a host range restriction in human lung A549 and pig kidney 15 cell lines that was attributed to apoptosis. Here we report that replication of a vaccinia virus SPI-1 deletion mutant (DeltaSPI-1) was restricted in primary human keratinocytes as well as A549 cells. Although chromatin condensation was detected in some A549 cells, other morphological or biochemical signs of apoptosis including DNA fragmentation, cleavage of poly(ADP-ribose)polymerase or nuclear mitotic apparatus protein, or caspase 3 activation were not found. Moreover, DeltaSPI-1 protected A549 cells from apoptosis induced by tumor necrosis factor, whereas the corresponding DeltaSPI-2 mutant did not. Further studies indicated undiminished amounts of vaccinia virus early mRNA and replicated DNA in the absence of the SPI-1 product. However, there were reduced amounts of viral intermediate and late mRNAs, viral late proteins, cleaved core proteins, and virus particles. These data suggested that apoptosis is not the determining factor in the host range restriction of DeltaSPI-1 and that the SPI-1 gene product is needed to allow efficient expression of intermediate and late genes in A549 cells.
Collapse
MESH Headings
- Apoptosis/genetics
- Caspase 3
- Caspases/metabolism
- Cell Line
- Cells, Cultured
- Chromatin/metabolism
- DNA, Viral/biosynthesis
- Gene Deletion
- Gene Expression Regulation, Viral
- Genes, Reporter/genetics
- Genes, Viral/genetics
- Humans
- In Situ Nick-End Labeling
- Keratinocytes/cytology
- Keratinocytes/enzymology
- Keratinocytes/ultrastructure
- Keratinocytes/virology
- Kinetics
- Microscopy, Electron
- Poly(ADP-ribose) Polymerases/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Serpins/genetics
- Serpins/physiology
- Vaccinia virus/genetics
- Vaccinia virus/growth & development
- Vaccinia virus/metabolism
- Vaccinia virus/ultrastructure
- Viral Proteins/biosynthesis
- Virus Assembly
- Virus Replication
Collapse
Affiliation(s)
- J L Shisler
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, 20892-0445, USA
| | | | | |
Collapse
|
47
|
Coppola MA, Flaño E, Nguyen P, Hardy CL, Cardin RD, Shastri N, Woodland DL, Blackman MA. Apparent MHC-Independent Stimulation of CD8+ T Cells In Vivo During Latent Murine Gammaherpesvirus Infection. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.3.1481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Like EBV-infected humans with infectious mononucleosis, mice infected with the rodent gammaherpesvirus MHV-68 develop a profound increase in the number of CD8+ T cells in the circulation. In the mouse model, this lymphocytosis consists of highly activated CD8+ T cells strikingly biased toward Vβ4 TCR expression. Moreover, this expansion of Vβ4+CD8+ T cells does not depend on the MHC haplotype of the infected animal. Using a panel of lacZ-inducible T cell hybridomas, we have detected Vβ4-specific T cell stimulatory activity in the spleens of MHV-68-infected mice. We show that the appearance and quantity of this activity correlate with the establishment and magnitude of latent viral infection. Furthermore, on the basis of Ab blocking studies as well as experiments with MHC class II, β2-microglobulin (β2m) and TAP1 knockout mice, the Vβ4-specific T cell stimulatory activity does not appear to depend on conventional presentation by classical MHC class I or class II molecules. Taken together, the data indicate that during latent infection, MHV-68 may express a T cell ligand that differs fundamentally from both conventional peptide Ags and classical viral superantigens.
Collapse
Affiliation(s)
- Michael A. Coppola
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Emilio Flaño
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Phuong Nguyen
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Charles L. Hardy
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Rhonda D. Cardin
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Nilabh Shastri
- †Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720; and
| | - David L. Woodland
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105
- ‡Department of Pathology, University of Tennessee, Memphis, TN 38163
| | - Marcia A. Blackman
- *Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105
- ‡Department of Pathology, University of Tennessee, Memphis, TN 38163
| |
Collapse
|
48
|
Virgin HW, Speck SH. Unraveling immunity to gamma-herpesviruses: a new model for understanding the role of immunity in chronic virus infection. Curr Opin Immunol 1999; 11:371-9. [PMID: 10448140 DOI: 10.1016/s0952-7915(99)80063-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Murine gamma-herpesvirus 68 (gammaHV68) infection is a new model for understanding how immunity and chronic gamma-herpesvirus infection inter-relate. gammaHV68 is closely related to the human Epstein-Barr virus and Kaposi's sarcoma herpesvirus and is associated with tumors, vasculitis of the great elastic arteries and splenic fibrosis. Advances in the past year have provided an even stronger foundation for believing that gammaHV68 infection of normal and mutant mice will become the pre-eminent animal model for understanding gamma-herpesvirus pathogenesis and immunity. gammaHV68 latency has been characterized employing new assays for quantitating cells carrying the gammaHV68 genome and cells that reactivate gammaHV68 and for detecting the presence of preformed infectious virus in tissues. These advances have fostered the first steps towards a molecular definition of gammaHV68 latency. It appears that gammaHV68 shares latency programs with human gamma-herpesviruses - including the loci for gene 73, v-bcl-2 and the viral homolog of the G-protein coupled receptor. This provides candidate antigens for analysis of the role of T and B cells in regulating latency. Multiple cellular reservoirs for gammaHV68 latency were uncovered with the demonstration that gammaHV68 latently infects macrophages in addition to B cells. A critical role for B cells in regulating the nature of gammaHV68 latency was discovered and the mechanism was shown to be via alteration of the efficiency of reactivation. Studies of the response of CD4(+) and CD8(+) cells during acute and chronic gammaHV68 were performed. These new studies provide key building blocks for further development of this novel and interesting model system.
Collapse
Affiliation(s)
- H W Virgin
- Department of Pathology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO 63110, USA.
| | | |
Collapse
|
49
|
Virgin HW, Presti RM, Li XY, Liu C, Speck SH. Three distinct regions of the murine gammaherpesvirus 68 genome are transcriptionally active in latently infected mice. J Virol 1999; 73:2321-32. [PMID: 9971815 PMCID: PMC104477 DOI: 10.1128/jvi.73.3.2321-2332.1999] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/1998] [Accepted: 12/03/1998] [Indexed: 11/20/2022] Open
Abstract
The program(s) of gene expression operating during murine gammaherpesvirus 68 (gammaHV68) latency is undefined, as is the relationship between gammaHV68 latency and latency of primate gammaherpesviruses. We used a nested reverse transcriptase PCR strategy (sensitive to approximately one copy of gammaHV68 genome for each genomic region tested) to screen for the presence of viral transcripts in latently infected mice. Based on the positions of known latency-associated genes in other gammaherpesviruses, we screened for the presence of transcripts corresponding to 11 open reading frames (ORFs) in the gammaHV68 genome in RNA from spleens and peritoneal cells of latently infected B-cell-deficient (MuMT) mice which have been shown contain high levels of reactivable latent gammaHV68 (K. E. Weck, M. L. Barkon, L. I. Yoo, S. H. Speck, and H. W. Virgin, J. Virol. 70:6775-6780, 1996). To control for the possible presence of viral lytic activity, we determined that RNA from latently infected peritoneal and spleen cells contained few or no detectable transcripts corresponding to seven ORFs known to encode viral gene products associated with lytic replication. However, we did detect low-level expression of transcripts arising from the region of gene 50 (encoding the putative homolog of the Epstein-Barr virus BRLF1 transactivator) in peritoneal but not spleen cells. Latently infected peritoneal cells consistently scored for expression of RNA derived from 4 of the 11 candidate latency-associated ORFs examined, including the regions of ORF M2, ORF M11 (encoding v-bcl-2), gene 73 (a homolog of the Kaposi's sarcoma-associated herpesvirus [human herpesvirus 8] gene encoding latency-associated nuclear antigen), and gene 74 (encoding a G-protein coupled receptor homolog, v-GCR). Latently infected spleen cells consistently scored positive for RNA derived from 3 of the 11 candidate latency-associated ORFs examined, including ORF M2, ORF M3, and ORF M9. To further characterize transcription of these candidate latency-associated ORFs, we examined their transcription in lytically infected fibroblasts by Northern analysis. We detected abundant transcription from regions of the genome containing ORF M3 and ORF M9, as well as the known lytic-cycle genes. However, transcription of ORF M2, ORF M11, gene 73, and gene 74 was barely detectable in lytically infected fibroblasts, consistent with a role of these viral genes during latent infection. We conclude that (i) we have identified several candidate latency genes of murine gammaHV68, (ii) expression of genes during latency may be different in different organs, consistent with multiple latency programs and/or multiple cellular sites of latency, and (iii) regions of the viral genome (v-bcl-2 gene, v-GCR gene, and gene 73) are transcribed during latency with both gammaHV68 and primate gammaherpesviruses. The implications of these findings for replacing previous operational definitions of gammaHV68 latency with a molecular definition are discussed.
Collapse
Affiliation(s)
- H W Virgin
- Center for Immunology and Departments of Pathology and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
| | | | | | | | | |
Collapse
|
50
|
Simas JP, Efstathiou S. Murine gammaherpesvirus 68: a model for the study of gammaherpesvirus pathogenesis. Trends Microbiol 1998; 6:276-82. [PMID: 9717216 DOI: 10.1016/s0966-842x(98)01306-7] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Murine gammaherpesvirus 68 (MHV-68) is a naturally occurring herpesvirus of wild rodents and is genetically related to human herpesvirus 8 and Epstein-Barr virus. The ability of MHV-68 to establish acute and persistent infection within laboratory mice offers a unique opportunity to investigate immunological and virological aspects of gammaherpesvirus pathogenesis.
Collapse
Affiliation(s)
- J P Simas
- Dept of Pathology, University of Cambridge, UK
| | | |
Collapse
|