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Abstract
Neurotropic strains of the mouse hepatitis virus (MHV) cause a range of diseases in infected mice ranging from mild encephalitis with clearance of the virus followed by demyelination to rapidly fatal encephalitis. This chapter discusses the structure, life cycle, transmission, and pathology of neurotropic coronaviruses, as well as the immune response to coronavirus infection. Mice infected with neurotropic strains of MHV have provided useful systems in which to study processes of virus- and immune-mediated demyelination and virus clearance and/or persistence in the CNS, and the mechanisms of virus evasion of the immune system.
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Trujillo JA, Gras S, Twist KA, Croft NP, Channappanavar R, Rossjohn J, Purcell AW, Perlman S. Structural and functional correlates of enhanced antiviral immunity generated by heteroclitic CD8 T cell epitopes. THE JOURNAL OF IMMUNOLOGY 2014; 192:5245-56. [PMID: 24795457 DOI: 10.4049/jimmunol.1400111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Peptides that bind poorly to MHC class I molecules often elicit low-functional avidity T cell responses. Peptide modification by altering the anchor residue facilitates increased binding affinity and may elicit T cells with increased functional avidity toward the native epitope ("heteroclitic"). This augmented MHC binding is likely to increase the half-life and surface density of the heteroclitic complex, but precisely how this enhanced T cell response occurs in vivo is not known. Furthermore, the ideal heteroclitic epitope will elicit T cell responses that completely cross-react with the native epitope, maximizing protection and minimizing undesirable off-target effects. Such epitopes have been difficult to identify. In this study, using mice infected with a murine coronavirus that encodes epitopes that elicit high (S510, CSLWNGPHL)- and low (S598, RCQIFANI)-functional avidity responses, we show that increased expression of peptide S598 but not S510 generated T cells with enhanced functional avidity. Thus, immune responses can be augmented toward T cell epitopes with low functional avidity by increasing Ag density. We also identified a heteroclitic epitope (RCVIFANI) that elicited a T cell response with nearly complete cross-reactivity with native epitope and demonstrated increased MHC/peptide abundance compared with native S598. Structural and thermal melt analyses indicated that the Q600V substitution enhanced stability of the peptide/MHC complex without greatly altering the antigenic surface, resulting in highly cross-reactive T cell responses. Our data highlight that increased peptide/MHC complex display contributes to heteroclitic epitope efficacy and describe parameters for maximizing immune responses that cross-react with the native epitope.
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Affiliation(s)
- Jonathan A Trujillo
- Interdisciplinary Program in Immunology, University of Iowa, Iowa City, IA 52242
| | - Stephanie Gras
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Kelly-Anne Twist
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Nathan P Croft
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia
| | | | - Jamie Rossjohn
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia; and Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - Anthony W Purcell
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Stanley Perlman
- Interdisciplinary Program in Immunology, University of Iowa, Iowa City, IA 52242; Department of Microbiology, University of Iowa, Iowa City, IA 52242;
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3
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Gispert S, Parganlija D, Klinkenberg M, Dröse S, Wittig I, Mittelbronn M, Grzmil P, Koob S, Hamann A, Walter M, Büchel F, Adler T, Hrabé de Angelis M, Busch DH, Zell A, Reichert AS, Brandt U, Osiewacz HD, Jendrach M, Auburger G. Loss of mitochondrial peptidase Clpp leads to infertility, hearing loss plus growth retardation via accumulation of CLPX, mtDNA and inflammatory factors. Hum Mol Genet 2013; 22:4871-87. [PMID: 23851121 PMCID: PMC7108587 DOI: 10.1093/hmg/ddt338] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The caseinolytic peptidase P (CLPP) is conserved from bacteria to humans. In the mitochondrial matrix, it multimerizes and forms a macromolecular proteasome-like cylinder together with the chaperone CLPX. In spite of a known relevance for the mitochondrial unfolded protein response, its substrates and tissue-specific roles are unclear in mammals. Recessive CLPP mutations were recently observed in the human Perrault variant of ovarian failure and sensorineural hearing loss. Here, a first characterization of CLPP null mice demonstrated complete female and male infertility and auditory deficits. Disrupted spermatogenesis already at the spermatid stage and ovarian follicular differentiation failure were evident. Reduced pre-/post-natal survival and marked ubiquitous growth retardation contrasted with only light impairment of movement and respiratory activities. Interestingly, the mice showed resistance to ulcerative dermatitis. Systematic expression studies detected up-regulation of other mitochondrial chaperones, accumulation of CLPX and mtDNA as well as inflammatory factors throughout tissues. T-lymphocytes in the spleen were activated. Thus, murine Clpp deletion represents a faithful Perrault model. The disease mechanism probably involves deficient clearance of mitochondrial components and inflammatory tissue destruction.
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Kyuwa S, Takagaki S, Matsuyama S, Taguchi F, Saegusa J, Iwakura Y, Tagawa YI, Yoshikawa Y. Characterization of a variant virus from ascitic fluid of subacute granulomatous serositis in interferon-gamma-deficient C57BL/6 mice persistently infected with murine coronavirus strain JHM. Viral Immunol 2011; 23:437-42. [PMID: 20712488 DOI: 10.1089/vim.2010.0008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Previously, we showed that intraperitoneal infection with murine coronavirus strain JHM (JHMV) established a persistent infection with subacute granulomatous serositis in interferon-gamma-deficient C57BL/6 (B6-GKO) mice. Herein, we characterize a variant virus from B6-GKO mice persistently infected with JHMV. Viruses were isolated from ascites at 25 d post-infection and cloned by limiting dilution on DBT cells; one variant was named 25V16G. To compare pathogenicity in vivo, we inoculated 25V16G and JHMV intraperitoneally into 8- to 12-week-old B6-GKO mice. Whereas nearly all of the B6-GKO mice infected with JHMV survived over 14 d, all of those infected with 25V16G died by 9 d post-infection. Histopathological examination revealed that 25V16G induced acute fulminant hepatitis in B6-GKO mice, whereas JHMV caused severe but focal hepatitis. The virus titer of 25V16G in the liver was 50- and 250-fold higher than that of JHMV at 5 and 7 d post-infection, respectively. However, there was no significant difference in viral growth between 25V16G and JHMV in cell lines cultured in vitro. Nucleotide sequencing of the S gene of 25V16G and JHMV revealed a deletion of 29 amino acids encompassing S(511-539), which covers a major cytotoxic T lymphocyte (CTL) epitope in C57BL/6 mice, and two point mutations resulting in amino acid changes in the S protein of 25V16G. One explanation for the greater pathogenicity of 25V16G is that 25V16G escapes CTL-mediated protection in B6-GKO mice. This experimental model may be used to assess the role of IFN-gamma in viral persistence in vivo.
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Affiliation(s)
- Shigeru Kyuwa
- Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
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Bender SJ, Weiss SR. Pathogenesis of murine coronavirus in the central nervous system. J Neuroimmune Pharmacol 2010; 5:336-54. [PMID: 20369302 PMCID: PMC2914825 DOI: 10.1007/s11481-010-9202-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 03/05/2010] [Indexed: 12/15/2022]
Abstract
Murine coronavirus (mouse hepatitis virus, MHV) is a collection of strains that induce disease in several organ systems of mice. Infection with neurotropic strains JHM and A59 causes acute encephalitis, and in survivors, chronic demyelination, the latter of which serves as an animal model for multiple sclerosis. The MHV receptor is a carcinoembryonic antigen-related cell adhesion molecule, CEACAM1a; paradoxically, CEACAM1a is poorly expressed in the central nervous system (CNS), leading to speculation of an additional receptor. Comparison of highly neurovirulent JHM isolates with less virulent variants and the weakly neurovirulent A59 strain, combined with the use of reverse genetics, has allowed mapping of pathogenic properties to individual viral genes. The spike protein, responsible for viral entry, is a major determinant of tropism and virulence. Other viral proteins, both structural and nonstructural, also contribute to pathogenesis in the CNS. Studies of host responses to MHV indicate that both innate and adaptive responses are crucial to antiviral defense. Type I interferon is essential to prevent very early mortality after infection. CD8 T cells, with the help of CD4 T cells, are crucial for viral clearance during acute disease and persist in the CNS during chronic disease. B cells are necessary to prevent reactivation of virus in the CNS following clearance of acute infection. Despite advances in understanding of coronavirus pathogenesis, questions remain regarding the mechanisms of viral entry and spread in cell types expressing low levels of receptor, as well as the unique interplay between virus and the host immune system during acute and chronic disease.
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Affiliation(s)
- Susan J Bender
- Department of Microbiology, University of Pennsylvania School of Medicine, 36th Street and Hamilton Walk, Philadelphia, PA 19104-6076, USA
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Butler NS, Theodossis A, Webb AI, Dunstone MA, Nastovska R, Ramarathinam SH, Rossjohn J, Purcell AW, Perlman S. Structural and biological basis of CTL escape in coronavirus-infected mice. THE JOURNAL OF IMMUNOLOGY 2008; 180:3926-37. [PMID: 18322201 DOI: 10.4049/jimmunol.180.6.3926] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cytotoxic T lymphocyte escape occurs in many human infections, as well as mice infected with the JHM strain of mouse hepatitis virus, which exhibit CTL escape variants with mutations in a single epitope from the spike glycoprotein (S510). In all CTL epitopes prone to escape, only a subset of all potential variants is generally detected, even though many of the changes that are not selected would result in evasion of the T cell response. It is postulated that these unselected mutations significantly impair virus fitness. To define more precisely the basis for this preferential selection, we combine x-ray crystallographic studies of the MHC class I (D(b))/S510 complexes with viral reverse genetics to identify a prominent TCR contact residue (tryptophan at position 4) prone to escape mutations. The data show that a mutation that is commonly detected in chronically infected mice (tryptophan to arginine) potently disrupts the topology of the complex, explaining its selection. However, other mutations at this residue, which also abrogate the CTL response, are never selected in vivo even though they do not compromise virus fitness in acutely infected animals or induce a significant de novo CTL response. Thus, while structural analyses of the S510/D(b) complex provide a strong basis for why some CTL escape variants are selected, our results also show that factors other than effects on virus fitness limit the diversification of CD8 T cell epitopes.
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Affiliation(s)
- Noah S Butler
- Department of Microbiology, University of Iowa, Iowa City, IA 52242, USA
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7
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Richter K, Baur K, Ackermann A, Schneider U, Hausmann J, Staeheli P. Pathogenic potential of borna disease virus lacking the immunodominant CD8 T-cell epitope. J Virol 2007; 81:11187-94. [PMID: 17686872 PMCID: PMC2045572 DOI: 10.1128/jvi.00742-07] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Borna disease virus (BDV) is a highly neurotropic, noncytolytic virus. Experimentally infected B10.BR mice remain healthy unless specific antiviral T cells that infiltrate the infected brain are triggered by immunization. In contrast, infected MRL mice spontaneously mount an antiviral T-cell response that can result in meningoencephalitis and neurological disease. The antiviral T cells may, alternatively, eliminate the virus without inducing disease if they are present in sufficient numbers before the virus replicates to high titers. Since the immune response of H-2(k) mice is directed mainly against the epitope TELEISSI located in the viral nucleoprotein N, we generated BDV mutants that feature TQLEISSI in place of TELEISSI. We show that adoptive transfer of BDV N-specific CD8 T cells induced neurological disease in B10.BR mice persistently infected with wild-type BDV but not with the mutant virus expressing TQLEISSI. Surprisingly, the mutant virus replicated less well in adult MRL wild-type mice than in mutant mice lacking mature CD8 T cells. Furthermore, when MRL mice were infected with the TQLEISSI-expressing BDV mutant as newborns, neurological disease was observed, although at a lower rate and with slower kinetics than in mice infected with wild-type virus. These results confirm that TELEISSI is the major CD8 T-cell epitope in H-2(k) mice and suggest that unidentified minor epitopes are present in the BDV proteome which are recognized rather efficiently by antiviral T cells if the dominant epitope is absent.
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Affiliation(s)
- Kirsten Richter
- Department of Virology, University of Freiburg, Hermann-Herder-Strasse 11, D-79104 Freiburg, Germany
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Ramos SJ, Hardison JL, Stiles LN, Lane TE, Walsh CM. Anti-viral effector T cell responses and trafficking are not dependent upon DRAK2 signaling following viral infection of the central nervous system. Autoimmunity 2007; 40:54-65. [PMID: 17364498 DOI: 10.1080/08916930600996700] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The signaling events involved in T cell trafficking into the central nervous system (CNS) following viral infection are not fully understood. Intracerebral infection of mice with mouse hepatitis virus (MHV) results in an acute encephalomyelitis followed by an immune-mediated demyelinating disease. Although chemokine signaling is critical in promoting T cell infiltration into the CNS and control of viral replication, additional signaling pathways have not been completely explored. DRAK2, a lymphoid-restricted serine/threonine kinase, prevents spurious T cell activation. Yet Drak2- / - mice are resistant to MOG-induced experimental autoimmune encephalomyelitis (EAE), suggesting that DRAK2 may influence T cell trafficking into the CNS. In order to further characterize the molecular mechanisms governing T cell activation and accumulation within the CNS in response to viral infection, MHV was instilled into the CNS of Drak2- / - mice. Drak2-deficient T cells possessed no obvious defects in trafficking into the CNS following MHV infection. Moreover, Drak2-deficient T cell activation, expansion and cytokine production were unimpaired in response to acute MHV infection. These results demonstrate that DRAK2 signaling is dispensable for T cell recruitment into the CNS following viral infection, suggesting that the resistance of Drak2- / - mice to EAE is not due to overt T cell trafficking defects.
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Affiliation(s)
- Stephanie J Ramos
- Center for Immunology and Department of Molecular Biology & Biochemistry, University of California, Irvine, CA, 92697-3900, USA
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Phares TW, Kean RB, Mikheeva T, Hooper DC. Regional differences in blood-brain barrier permeability changes and inflammation in the apathogenic clearance of virus from the central nervous system. THE JOURNAL OF IMMUNOLOGY 2006; 176:7666-75. [PMID: 16751414 DOI: 10.4049/jimmunol.176.12.7666] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The loss of blood-brain barrier (BBB) integrity in CNS inflammatory responses triggered by infection and autoimmunity has generally been associated with the development of neurological signs. In the present study, we demonstrate that the clearance of the attenuated rabies virus CVS-F3 from the CNS is an exception; increased BBB permeability and CNS inflammation occurs in the absence of neurological sequelae. We speculate that regionalization of the CNS inflammatory response contributes to its lack of pathogenicity. Despite virus replication and the expression of several chemokines and IL-6 in both regions being similar, the up-regulation of MIP-1beta, TNF-alpha, IFN-gamma, and ICAM-1 and the loss of BBB integrity was more extensive in the cerebellum than in the cerebral cortex. The accumulation of CD4- and CD19-positive cells was higher in the cerebellum than the cerebral cortex. Elevated CD19 levels were paralleled by kappa-L chain expression levels. The timing of BBB permeability changes, kappa-L chain expression in CNS tissues, and Ab production in the periphery suggest that the in situ production of virus-neutralizing Ab may be more important in virus clearance than the infiltration of circulating Ab. The data indicate that, with the possible exception of CD8 T cells, the effectors of rabies virus clearance are more commonly targeted to the cerebellum. This is likely the result of differences in the capacity of the tissues of the cerebellum and cerebral cortex to mediate the events required for BBB permeability changes and cell invasion during virus infection.
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Affiliation(s)
- Timothy W Phares
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Chen W, McCluskey J. Immunodominance and Immunodomination: Critical Factors in Developing Effective CD8+ T‐Cell–Based Cancer Vaccines. Adv Cancer Res 2006; 95:203-47. [PMID: 16860659 DOI: 10.1016/s0065-230x(06)95006-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The focusing of cellular immunity toward one, or just a few, antigenic determinant, even during immune responses to complex microorganisms or antigens, is known as immunodominance. Although described in many systems, the mechanisms of determinant immunodominance are only just beginning to be appreciated, especially in relation to the interplay between T cells of differing specificities and the interactions between T cells and the antigen-presenting cells (APCs). The outcome of these cellular interactions can lead to a form of immune suppression of one specificity by another-described as "immunodomination". The specific and detailed mechanisms involved in this process are now partly defined. A full understanding of all the factors that control immunodominance and influence immunodomination will help us to develop better viral and cancer vaccines.
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Affiliation(s)
- Weisan Chen
- T Cell Laboratory, Ludwig Institute for Cancer Research, Austin Health, Heidelberg, VIC 3084, Australia
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Hardison JL, Nistor G, Gonzalez R, Keirstead HS, Lane TE. Transplantation of glial-committed progenitor cells into a viral model of multiple sclerosis induces remyelination in the absence of an attenuated inflammatory response. Exp Neurol 2005; 197:420-9. [PMID: 16297915 PMCID: PMC7094399 DOI: 10.1016/j.expneurol.2005.10.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2005] [Revised: 09/26/2005] [Accepted: 10/06/2005] [Indexed: 12/29/2022]
Abstract
Transplantation of remyelination-competent cells represents a promising strategy for the treatment of demyelinating diseases. As the environment dictates the success or failure of remyelination, it is critical to understand the role that the immune system plays in transplant-mediated remyelination. In this study, we evaluated the severity of neuroinflammation following transplantation of glial-committed progenitor cells into the spinal cords of mice chronically infected with mouse hepatitis virus (MHV), a model in which T cells and macrophages are critical in amplifying the severity of demyelination. Transplantation was performed following viral persistence in which inflammation and demyelination are established and clinical disease is evident. Mice were sacrificed 10 and 21 days following progenitor cell transplantation and the effect on neuroinflammation evaluated. Treatment did not alter accumulation of T cells or macrophages within the CNS as compared to control mice. Moreover, progenitor cell implantation did not affect local cytokine/chemokine gene expression in the CNS. Finally, remyelination associated with transplantation did not result in an imbalance of TH1-associated cytokine production by virus-specific T cells. These studies demonstrate that progenitor cell-mediated remyelination is not the result of modulating the composition of the cellular infiltrate nor cytokine expression by virus-specific T cells and suggest that remyelination may not depend on amelioration of the inflammatory response or alteration of cytokine secretion by virus-specific T cells.
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Affiliation(s)
- Jenny L. Hardison
- Department of Molecular Biology and Biochemistry, 3205 McGaugh Hall, University of California, Irvine, CA 92697-3900, USA
| | - Gabriel Nistor
- Reeve-Irvine Research Center, Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-4120, USA
| | - Rafael Gonzalez
- Reeve-Irvine Research Center, Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-4120, USA
| | - Hans S. Keirstead
- Reeve-Irvine Research Center, Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, CA 92697-4120, USA
- Corresponding authors. H.S. Keirstead is to be contacted at fax: +1 949 824 2625. T.E. Lane, Department of Molecular Biology and Biochemistry, 3205 McGaugh Hall, University of California, Irvine, CA 92697-3900, USA. Fax: +1 949 924 8551.
| | - Thomas E. Lane
- Department of Molecular Biology and Biochemistry, 3205 McGaugh Hall, University of California, Irvine, CA 92697-3900, USA
- Center for Immunology, University of California, Irvine, CA 92697-3900, USA
- Corresponding authors. H.S. Keirstead is to be contacted at fax: +1 949 824 2625. T.E. Lane, Department of Molecular Biology and Biochemistry, 3205 McGaugh Hall, University of California, Irvine, CA 92697-3900, USA. Fax: +1 949 924 8551.
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Vukmanović S, Santori FR. Self-peptide/MHC and TCR antagonism: physiological role and therapeutic potential. Cell Immunol 2005; 233:75-84. [PMID: 15950208 DOI: 10.1016/j.cellimm.2005.04.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Accepted: 04/21/2005] [Indexed: 10/25/2022]
Abstract
TCR antagonists are peptides that bind MHC molecules and can specifically inhibit T cell activation induced by antigens. Studying TCR antagonism has taken an important place in immunology for both theoretical and practical reasons. Deciphering the mechanism(s) of action of TCR antagonists can yield important information about interactions of the TCR with ligands, T cell development, and TCR signaling. Moreover, microorganisms may employ TCR antagonism to elude the attention of the immune system. Finally, specificity of inhibition makes TCR antagonists an ideal tool to seek antigen-specific immunomodulation. Present state of knowledge on these topics is reviewed.
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Affiliation(s)
- Stanislav Vukmanović
- Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010-2970, USA.
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MacNamara KC, Chua MM, Phillips JJ, Weiss SR. Contributions of the viral genetic background and a single amino acid substitution in an immunodominant CD8+ T-cell epitope to murine coronavirus neurovirulence. J Virol 2005; 79:9108-18. [PMID: 15994805 PMCID: PMC1168726 DOI: 10.1128/jvi.79.14.9108-9118.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The immunodominant CD8+ T-cell epitope of a highly neurovirulent strain of mouse hepatitis virus (MHV), JHM, is thought to be essential for protection against virus persistence within the central nervous system. To test whether abrogation of this H-2Db-restricted epitope, located within the spike glycoprotein at residues S510 to 518 (S510), resulted in delayed virus clearance and/or virus persistence we selected isogenic recombinants which express either the wild-type JHM spike protein (RJHM) or spike containing the N514S mutation (RJHM(N514S)), which abrogates the response to S510. In contrast to observations in suckling mice in which viruses encoding inactivating mutations within the S510 epitope (epitope escape mutants) were associated with persistent virus and increased neurovirulence (Pewe et al., J Virol. 72:5912-5918, 1998), RJHM(N514S) was not more virulent than the parental, RJHM, in 4-week-old C57BL/6 (H-2b) mice after intracranial injection. Recombinant viruses expressing the JHM spike, wild type or encoding the N514S substitution, were also selected in which background genes were derived from the neuroattenuated A59 strain of MHV. Whereas recombinants expressing the wild-type JHM spike (SJHM/RA59) were highly neurovirulent, A59 recombinants containing the N514S mutation (SJHM(N514S)/RA59) were attenuated, replicated less efficiently, and exhibited reduced virus spread in the brain at 5 days postinfection (peak of infectious virus titers in the central nervous system) compared to parental virus encoding wild-type spike. Virulence assays in BALB/c mice (H-2d), which do not recognize the S510 epitope, revealed that attenuation of the epitope escape mutants was not due to the loss of a pathogenic immune response directed against the S510 epitope. Thus, an intact immunodominant S510 epitope is not essential for virus clearance from the CNS, the S510 inactivating mutation results in decreased virulence in weanling mice but not in suckling mice, suggesting that specific host conditions are required for epitope escape mutants to display increased virulence, and the N514S mutation causes increased attenuation in the context of A59 background genes, demonstrating that genes other than that for the spike are also important in determining neurovirulence.
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Affiliation(s)
- Katherine C MacNamara
- Department of Microbiology, University of Pennsylvania, School of Medicine, 36th Street and Hamilton Walk, Philadelphia, PA 19104-6076, USA
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The Role of T Cell Epitopes in Coronavirus Infection. EXPERIMENTAL MODELS OF MULTIPLE SCLEROSIS 2005. [PMCID: PMC7122487 DOI: 10.1007/0-387-25518-4_42] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Multiple MHV-specific CD4 and CD8 T cell epitopes have been identified in C57Bl/6 and BALB/c mice. In particular, at least two CD8 T cell epitopes are recognized in C57Bl/6 mice. In one model of MHV persistence, mutations are detected in the immunodominant CD8 T cell epitope recognized in this strain. These mutations contribute to virus persistence and to the development of more severe clinical disease.
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Poluektova L, Gorantla S, Faraci J, Birusingh K, Dou H, Gendelman HE. Neuroregulatory events follow adaptive immune-mediated elimination of HIV-1-infected macrophages: studies in a murine model of viral encephalitis. THE JOURNAL OF IMMUNOLOGY 2004; 172:7610-7. [PMID: 15187141 DOI: 10.4049/jimmunol.172.12.7610] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
HIV-1-specific cellular immunity serves to eliminate infected cells and disease. However, how this process specifically affects the CNS is poorly understood. To mirror the regulatory events that occur in human brain after HIV-1 infection, a murine model of viral encephalitis was used to study relationships, over time, among lymphocyte-mediated infected cell elimination, innate immune responses, and neuropathology. Nonobese diabetic SCID mice were reconstituted with human PBL and a focal encephalitis induced by intracranial injection of autologous HIV-1-infected, monocyte-derived macrophages (MDM). On days 7, 14, and 21 after MDM injection into the basal ganglia, the numbers of human lymphocytes and mouse monocytes, virus-infected MDM, glial (astrocyte and microglial) responses, cytokines, inducible NO (iNOS), neurotrophic factors, and neuronal Ags were determined in brain by immunohistochemistry, real-time PCR, and Western blot assays. Microglia activation, astrocytosis, proinflammatory cytokines, and iNOS expression accompanied the loss of neuronal Ags. This followed entry of human lymphocytes and mouse monocytes into the brain on days 7 and 14. Elimination of virus-infected human MDM, expression of IL-10, neurotropins, and a down-regulation of iNOS coincided with brain tissue restoration. Our results demonstrate that the degree of tissue damage and repair parallels the presence of infected macrophages and effectors of innate and adaptive immunity. This murine model of HIV-1 encephalitis can be useful in elucidating the role played by innate and adaptive immunity in disease progression and resolution.
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Affiliation(s)
- Larisa Poluektova
- Laboratory of Neuroregeneration, Center for Neurovirology and Neurodegenerative Disorders, and Department of Pathology and Microbiology, University of Nebraska Medical Center, 958215 Nebraska Medical Center, Omaha, NE 68198-5215, USA.
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16
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De Groot AS. How the SARS vaccine effort can learn from HIV-speeding towards the future, learning from the past. Vaccine 2004; 21:4095-104. [PMID: 14505885 PMCID: PMC7126672 DOI: 10.1016/s0264-410x(03)00489-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A remarkable collaborative effort coordinated by the severe acute respiratory syndrome (SARS) team at WHO resulted in discovery of the etiologic agent of severe acute respiratory syndrome less than 2 months after the announcement of global alert. The development of a vaccine to prevent SARS should be pursued with the same urgency and cooperative spirit, as SARS is highly lethal and, if not controlled during the first few generations of transmission, is likely to become endemic in regions of the world where health-care infrastructure is underdeveloped and epidemiological control measures are weak. The scientific community already learned many important lessons from HIV vaccine development; these should be heeded. For example, consideration should be given to the development of a vaccine that will protect across regional strains of SARS, as the newly emergent coronavirus SARS-coronavirus (SARS-CoV) is proving to be variable and may be mutating in response to immune pressure. SARS-specific research reagents should also be collected and shared. These would include SARS peptides, adjuvants, DNA vaccine vectors and clinical grade viral vectors. Rapidly developing a collaborative approach to developing a SARS vaccine that will be both effective and safe is the only way to go. This article reviews parallels between HIV and SARS and proposes an approach that would accelerate the development of a SARS vaccine.
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Affiliation(s)
- Anne S De Groot
- TB/HIV Research Laboratory, Brown University, Providence, RI 02912, USA.
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17
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Kim TS, Perlman S. Protection against CTL escape and clinical disease in a murine model of virus persistence. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:2006-13. [PMID: 12902505 DOI: 10.4049/jimmunol.171.4.2006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CTL escape mutations have been identified in several chronic infections, including mice infected with mouse hepatitis virus strain JHM. One outstanding question in understanding CTL escape is whether a CD8 T cell response to two or more immunodominant CTL epitopes would prevent CTL escape. Although CTL escape at multiple epitopes seems intuitively unlikely, CTL escape at multiple CD8 T cell epitopes has been documented in some chronically infected individual animals. To resolve this apparent contradiction, we engineered a recombinant variant of JHM that expressed the well-characterized gp33 epitope of lymphocytic choriomeningitis virus, an epitope with high functional avidity. The results show that the presence of a host response to this second epitope protected mice against CTL escape at the immunodominant JHM-specific CD8 T cell epitope, the persistence of infectious virus, and the development of clinical disease.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Viral/administration & dosage
- Antigens, Viral/analysis
- Antigens, Viral/biosynthesis
- Antigens, Viral/genetics
- Chronic Disease
- Coronavirus Infections/genetics
- Coronavirus Infections/immunology
- Coronavirus Infections/prevention & control
- Disease Models, Animal
- Encephalomyelitis/genetics
- Encephalomyelitis/immunology
- Encephalomyelitis/prevention & control
- Encephalomyelitis/virology
- Epitopes, T-Lymphocyte/administration & dosage
- Epitopes, T-Lymphocyte/analysis
- Epitopes, T-Lymphocyte/biosynthesis
- Epitopes, T-Lymphocyte/genetics
- Female
- Gene Deletion
- Glycoproteins/administration & dosage
- Glycoproteins/analysis
- Glycoproteins/biosynthesis
- Glycoproteins/genetics
- HeLa Cells
- Humans
- Lymphocytic choriomeningitis virus/genetics
- Lymphocytic choriomeningitis virus/immunology
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Molecular Sequence Data
- Murine hepatitis virus/genetics
- Murine hepatitis virus/immunology
- Peptide Fragments/administration & dosage
- Peptide Fragments/analysis
- Peptide Fragments/biosynthesis
- Peptide Fragments/genetics
- Recombinant Fusion Proteins/administration & dosage
- Recombinant Fusion Proteins/biosynthesis
- Recombinant Fusion Proteins/chemical synthesis
- Recombinant Fusion Proteins/immunology
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
- T-Lymphocytes, Cytotoxic/virology
- Vaccines, Synthetic/administration & dosage
- Vaccines, Synthetic/biosynthesis
- Vaccines, Synthetic/chemistry
- Vaccines, Synthetic/immunology
- Viral Proteins/administration & dosage
- Viral Proteins/analysis
- Viral Proteins/biosynthesis
- Viral Proteins/genetics
- Virus Latency/genetics
- Virus Latency/immunology
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Affiliation(s)
- Taeg S Kim
- Interdisciplinary Program in Immunology, Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
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18
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Daniels RS, Kang C, Patel D, Xiang Z, Douglas NW, Zheng NN, Cho HW, Lee JS. An HIV type 1 subtype B founder effect in Korea: gp160 signature patterns infer circulation of CTL-escape strains at the population level. AIDS Res Hum Retroviruses 2003; 19:631-41. [PMID: 13678464 DOI: 10.1089/088922203322280847] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HIV-1 subtype B predominates in the Republic of Korea. Phylogenetic analyses of sequences for complete nef genes and env gene fragments encoding the V3 loop have identified a major monophyletic Korean subclade that is distinct from Western subtype B sequences in the Los Alamos HIV Sequence Database. This was investigated further by sequence analysis of complete env genes recovered from the DNA of peripheral blood mononuclear cells for matched groups of Koreans, four patients per group, previously assigned as being infected with either Korean or Western strains. The phylogenetic classifications were confirmed and analysis of the translation products identified 32 amino acid signature pattern differences, dispersed throughout gp160, which differentiate the two subclades. Twenty-three of these positions map to epitopes recognized by HLA-I-restricted cytotoxic T-lymphocytes (CTL) as catalogued in the Los Alamos HIV Immunology Database. The remaining nine map at or close to sites predicted to be targets for immunoproteasomes that are involved in producing peptides that bind to MHC Class I. These results suggest that a founder effect in the Korean population is based on the spread of CTL-escape/host-adapted HIV-1 strains.
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Affiliation(s)
- Rod S Daniels
- Virology Division, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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19
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Vukmanović S, Neubert TA, Santori FR. Could TCR antagonism explain associations between MHC genes and disease? Trends Mol Med 2003; 9:139-46. [PMID: 12727139 DOI: 10.1016/s1471-4914(03)00029-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Alleles of major histocompatibility complex (MHC) loci are associated with certain types of diseases, including those of infectious and autoimmune origin. MHC products can promote susceptibility or resistance to disease by stimulating or inhibiting immune responses. Recent evidence suggests that MHC-associated peptides derived from self-proteins can act as antagonists of T-cell activation, thereby inhibiting immune responses to antigens. We suggest that self-peptide-promoted antagonism might explain some associations between MHC alleles and particular chronic diseases.
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Affiliation(s)
- Stanislav Vukmanović
- Michael Heidelberger Division of Immunology, Department of Pathology and NYU Cancer Center, NYU School of Medicine, New York, NY 10016, USA.
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20
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Phillips JJ, Chua MM, Rall GF, Weiss SR. Murine coronavirus spike glycoprotein mediates degree of viral spread, inflammation, and virus-induced immunopathology in the central nervous system. Virology 2002; 301:109-20. [PMID: 12359451 PMCID: PMC7131834 DOI: 10.1006/viro.2002.1551] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The mouse hepatitis virus (MHV) spike glycoprotein is a major determinant of neurovirulence. We investigated how alterations in spike affect neurovirulence using two isogenic recombinant viruses differing exclusively in spike. S(4)R, containing the MHV-4 spike gene, is dramatically more neurovirulent than S(A59)R, containing the MHV-A59 spike gene (J. J. Phillips, M. M. Chua, E. Lavi, and S. R. Weiss, 1999, J. Virol. 73, 7752-7760). We examined the contribution of differences in cellular tropism, viral spread, and the immune response to infection to the differential neurovirulence of S(4)R and S(A59)R. MHV-4 spike-mediated neurovirulence was associated with extensive viral spread in the brain in both neurons and astrocytes. Infection of primary hippocampal neuron cultures demonstrated that S(4)R spread more rapidly than S(A59)R and suggested that spread may occur between cells in close physical contact. In addition, S(4)R infection induced a massive influx of lymphocytes into the brain, a higher percentage of CD8(+) T cells, and a higher frequency of MHV-specific CD8(+) T cells relative S(A59)R infection. Despite this robust and viral-specific immune response to S(4)R infection, infection of RAG1-/- mice suggested that immune-mediated pathology also contributes to the high neurovirulence of S(4)R.
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Affiliation(s)
- Joanna J Phillips
- Department of Microbiology, University of pennsylvania School of Medicine, Philadelphia 19104-6076, USA
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21
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Oldstone MBA. Biology and pathogenesis of lymphocytic choriomeningitis virus infection. Curr Top Microbiol Immunol 2002; 263:83-117. [PMID: 11987822 DOI: 10.1007/978-3-642-56055-2_6] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- M B A Oldstone
- Division of Virology, Department of Neuropharmacology, Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, USA
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22
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Abstract
Feline infectious peritonitis (FIP) is a common cause of death in cats. Management of this disease has been hampered by difficulties identifying the infection and determining the immunological status of affected cats and by high variability in the clinical, pathological, and immunological characteristics of affected cats. Neurological FIP, which is much more homogeneous than systemic effusive or noneffusive FIP, appears to be a good model for establishing the basic features of FIP immunopathogenesis. Very little information is available about the immunopathogenesis of neurologic FIP, and it is reasonable to use research from the well-characterized mouse hepatitis virus (MHV) immune-mediated encephalitis system, as a template for FIP investigation, and to contrast findings from the MHV model with those of FIP. It is expected that the immunopathogenic mechanisms will have important similarities. Such comparative research may lead to better understanding of FIP immunopathogenesis and rational prospects for management of this frustrating disease.
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Affiliation(s)
- J E Foley
- School of Veterinary Medicine, Department of Medicine and Epidemiology, University of California, Davis 95616, USA.
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23
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Abstract
Feline infectious peritonitis (FIP) is a common cause of death in cats. Management of this disease has been hampered by difficulties identifying the infection and determining the immunological status of affected cats and by high variability in the clinical, pathological, and immunological characteristics of affected cats. Neurological FIP, which is much more homogeneous than systemic effusive or noneffusive FIP, appears to be a good model for establishing the basic features of FIP immunopathogenesis. Very little information is available about the immunopathogenesis of neurologic FIP, and it is reasonable to use research from the well-characterized mouse hepatitis virus (MHV) immune-mediated encephalitis system, as a template for FIP investigation, and to contrast findings from the MHV model with those of FIP. It is expected that the immunopathogenic mechanisms will have important similarities. Such comparative research may lead to better understanding of FIP immunopathogenesis and rational prospects for management of this frustrating disease.
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Affiliation(s)
- J E Foley
- School of Veterinary Medicine, Department of Medicine and Epidemiology, University of California, Davis 95616, USA.
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24
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Das Sarma J, Fu L, Hingley ST, Lavi E. Mouse hepatitis virus type-2 infection in mice: an experimental model system of acute meningitis and hepatitis. Exp Mol Pathol 2001; 71:1-12. [PMID: 11502093 DOI: 10.1006/exmp.2001.2378] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Infection with mouse hepatitis virus (MHV) strain A59 produces acute hepatitis, encephalitis, and chronic demyelination in mice. However, little is known about a closely related strain, MHV-2, which is only weakly neurotropic. To better understand the molecular basis of neurotropism of MHVs, we compared the pathogenesis and genomic sequence of MHV-2 with that of MHV-A59. Intracerebral injection of MHV-2 into 4-week-old C57B1/6 mice produces acute meningitis and hepatitis without encephalitis or chronic inflammatory demyelination. Sequence comparison between MHV-2 and MHV-A59 reveals 94-98% sequence identity of the replicase gene, 83-95% sequence identity of genes 2a, 3, 5b, 6, and 7, and marked difference in the sequence of genes, 2b, 4, and 5a. This information provides the basis for further studies exploring the mechanism of viral neurotropism and virus-induced demyelination.
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Affiliation(s)
- J Das Sarma
- Division of Neuropathology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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25
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Abstract
Cytotoxic CD8 T lymphocytes (CTLs) are critical for the clearance of noncytopathic viruses from infected cells. This chapter discusses one mechanism used by viruses to persist—namely, the selection of a variant virus in which changes in the sequence of a CTL epitope abrogate recognition. The unique features of cytotoxic CD8 T cell function in the central nervous system (CNS) are discussed. The role of CTL escape mutants in the viral evasion of the immune system and subsequent disease progression in non-CNS infections are summarized. The immune response in the CNS is similar to the response in extraneural tissue, but several aspects of the activation of the immune response, cellular trafficking, and antigen presentation are unique to the CNS. Although the CNS has classically been considered a site of immune privilege, surveillance of the normal CNS by circulating, activated lymphocytes occurs, with a limited number of lymphocytes being present in the normal CNS at any given time. In mice infected with mouse hepatitis virus and in some humans persistently infected with human immunodeficiency virus type1, hepatitis B virus or hepatitis C virus, CTL escape mutants play an important role in virus amplification and disease progression.
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Affiliation(s)
- S Perlman
- Departments of Pediatrics and Microbiology, University of Iowa, Iowa City, Iowa 52242, USA
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26
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Lane TE, Liu MT, Chen BP, Asensio VC, Samawi RM, Paoletti AD, Campbell IL, Kunkel SL, Fox HS, Buchmeier MJ. A central role for CD4(+) T cells and RANTES in virus-induced central nervous system inflammation and demyelination. J Virol 2000; 74:1415-24. [PMID: 10627552 PMCID: PMC111476 DOI: 10.1128/jvi.74.3.1415-1424.2000] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Infection of C57BL/6 mice with mouse hepatitis virus (MHV) results in a demyelinating encephalomyelitis characterized by mononuclear cell infiltration and white matter destruction similar to the pathology of the human demyelinating disease multiple sclerosis. The contributions of CD4(+) and CD8(+) T cells in the pathogenesis of the disease were investigated. Significantly less severe inflammation and demyelination were observed in CD4(-/-) mice than in CD8(-/-) and C57BL/6 mice (P < or = 0.002 and P < or = 0.001, respectively). Immunophenotyping of central nervous system (CNS) infiltrates revealed that CD4(-/-) mice had a significant reduction in numbers of activated macrophages/microglial cells in the brain compared to the numbers in CD8(-/-) and C57BL/6 mice, indicating a role for these cells in myelin destruction. Furthermore, CD4(-/-) mice displayed lower levels of RANTES (a C-C chemokine) mRNA transcripts and protein, suggesting a role for this molecule in the pathogenesis of MHV-induced neurologic disease. Administration of RANTES antisera to MHV-infected C57BL/6 mice resulted in a significant reduction in macrophage infiltration and demyelination (P < or = 0.001) compared to those in control mice. These data indicate that CD4(+) T cells have a pivotal role in accelerating CNS inflammation and demyelination within infected mice, possibly by regulating RANTES expression, which in turn coordinates the trafficking of macrophages into the CNS, leading to myelin destruction.
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Affiliation(s)
- T E Lane
- Department of Molecular Biology and Biochemistry, University of California-Irvine, Irvine, California.
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27
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Pewe L, Heard SB, Bergmann C, Dailey MO, Perlman S. Selection of CTL Escape Mutants in Mice Infected with a Neurotropic Coronavirus: Quantitative Estimate of TCR Diversity in the Infected Central Nervous System. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.11.6106] [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
Variant viruses mutated in the immunodominant cytotoxic T cell epitope surface (S) glycoprotein S-510-518 are selected in mice chronically infected with mouse hepatitis virus, strain JHM. We determined whether this selection occurred in the presence of an oligoclonal or polyclonal T cell response using soluble MHC/peptide tetramers in direct ex vivo analyses of CNS-derived lymphocytes. A total of 42% (range, 29–60%) of CD8 T cells in the CNS of mice with acute encephalitis recognized epitope S-510-518. A total of 34% (range, 18–62%) of cells from mice with hind limb paralysis (and chronic demyelination) were also epitope specific, even though only virus expressing mutated epitope is detected in these animals. Sequence analysis of the β-chain CDR3 of 487 tetramer S-510-518-positive cDNA clones from nine mice showed that a majority of clonotypes were identified in more than one mouse. From these analyses, we estimated that 300–500 different CD8 T cell clonotypes responsive to epitope S-510-518 were present in each acutely infected brain, while 100–900 were present in the CNS of each mouse with chronic disease. In conclusion, a polyclonal CD8 T cell response to an epitope does not preclude the selection of T cell escape mutants, and epitope-specific T cells are still present at high levels even after RNA-encoding wild-type sequence is no longer detectable.
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Affiliation(s)
| | | | - Conni Bergmann
- ∥Departments of Neurology and Molecular Microbiology and Immunology, University of Southern California School of Medicine, Los Angeles, CA 90033
| | - Morris O. Dailey
- ‡Pathology, and
- §Microbiology and the
- ¶Interdisciplinary Program in Immunology, University of Iowa, Iowa City, IA 52242; and
| | - Stanley Perlman
- *Pediatrics,
- §Microbiology and the
- ¶Interdisciplinary Program in Immunology, University of Iowa, Iowa City, IA 52242; and
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28
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Xue S, Sun N, Van Rooijen N, Perlman S. Depletion of blood-borne macrophages does not reduce demyelination in mice infected with a neurotropic coronavirus. J Virol 1999; 73:6327-34. [PMID: 10400724 PMCID: PMC112711 DOI: 10.1128/jvi.73.8.6327-6334.1999] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mice infected with the neurotropic coronavirus mouse hepatitis virus strain JHM (MHV-JHM) develop a chronic demyelinating disease with symptoms of hindlimb paralysis. Histological examination of the brains and spinal cords of these animals reveals the presence of large numbers of activated macrophages/microglia. In two other experimental models of demyelination, experimental allergic encephalomyelitis and Theiler's murine encephalomyelitis virus-induced demyelination, depletion of hematogenous macrophages abrogates the demyelinating process. In both of these diseases, early events in the demyelinating process are inhibited by macrophage depletion. From these studies, it was not possible to determine whether infiltrating macrophages were required for late steps in the process, such as myelin removal. In this study, we show that when macrophages are depleted with either unmodified or mannosylated liposomes encapsulating dichloromethylene diphosphate, the amount of demyelination detected in MHV-infected mice is not affected. At a time when these cells were completely depleted from the liver, approximately equivalent numbers of macrophages were present in the spinal cords of control and drug-treated animals. These results suggest that blood-borne macrophages are not required for MHV-induced demyelination and also suggest that other cells, such as perivascular macrophages or microglia, perform the function of these cells in the presence of drug.
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Affiliation(s)
- S Xue
- Departments of Microbiology, University of Iowa, Iowa City, Iowa 52242, USA
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29
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Pewe L, Perlman S. Immune response to the immunodominant epitope of mouse hepatitis virus is polyclonal, but functionally monospecific in C57Bl/6 mice. Virology 1999; 255:106-16. [PMID: 10049826 DOI: 10.1006/viro.1998.9576] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Mutations in an immunodominant CD8 CTL epitope (S-510-518) are selected in mice persistently infected with the neurotropic JHM strain of mouse hepatitis virus. These mutations abrogate recognition by T cells harvested from the infected CNS in direct ex vivo cytotoxicity assays. Previous reports have suggested that, in general, an oligoclonal, monospecific T cell response contributes to the selection of CTL escape mutants. Herein, we show that, in MHV-JHM-infected mice, the CD8 T cell response after intraperitoneal infection is polyclonal and diverse. This diverse response was shown to include both polyclonal and oligoclonal components. The polyclonal data were shown to fit a logarithmic distribution. With regard to specificity, we used a panel of peptide analogues of epitope S-510-518 and spleen-derived CD8 T cell lines to determine why only a subset of possible mutations was selected in persistently infected mice. At a given position in the epitope, the mutations identified in in vivo isolates were among those that resulted in the greatest loss of recognition. However, not all such mutations were selected, suggesting that additional factors must contribute to selection in vivo. By extrapolation of these results to the persistently infected CNS, they suggest that the selection of CTL escape mutants requires the presence of a monospecific T cell response but also show that this response need not be oligoclonal.
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Affiliation(s)
- L Pewe
- Department of Pediatrics, University of Iowa, Iowa City, Iowa 52242, USA
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