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Deng Y, Ostermann E, Brune W. A cytomegalovirus inflammasome inhibitor reduces proinflammatory cytokine release and pyroptosis. Nat Commun 2024; 15:786. [PMID: 38278864 PMCID: PMC10817922 DOI: 10.1038/s41467-024-45151-z] [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: 04/24/2023] [Accepted: 01/17/2024] [Indexed: 01/28/2024] Open
Abstract
In response to viral infection, cells can initiate programmed cell death (PCD), leading to a reduction in the release of viral progeny. Viruses have therefore evolved specific mechanisms to curb PCD. Cytomegaloviruses (CMVs) are sophisticated manipulators of cellular defenses and encode potent inhibitors of apoptosis and necroptosis. However, a CMV inhibitor of pyroptosis has not been clearly identified and characterized. Here we identify the mouse cytomegalovirus M84 protein as an inhibitor of pyroptosis and proinflammatory cytokine release. M84 interacts with the pyrin domain of AIM2 and ASC to inhibit inflammasome assembly. It thereby prevents Caspase-1-mediated activation of interleukin 1β (IL-1β), IL-18, and Gasdermin D. Growth attenuation of an M84-deficient MCMV in macrophages is rescued by knockout of either Aim2 or Asc or by treatment with a Caspase-1 inhibitor, and its attenuation in infected mice is partially rescued in Asc knockout mice. Thus, viral inhibition of the inflammasome-pyroptosis pathway is important to promote viral replication in vivo.
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Affiliation(s)
- Yingqi Deng
- Leibniz Institute of Virology (LIV), Hamburg, Germany
| | | | - Wolfram Brune
- Leibniz Institute of Virology (LIV), Hamburg, Germany.
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Abstract
Cytomegaloviruses (CMVs) are among the largest pathogenic viruses in mammals. To enable replication of their long double-stranded DNA genomes, CMVs induce profound changes in cell cycle regulation. A hallmark of CMV cell cycle control is the establishment of an unusual cell cycle arrest at the G1/S transition, which is characterized by the coexistence of cell cycle stimulatory and inhibitory activities. While CMVs interfere with cellular DNA synthesis and cell division, they activate S-phase-specific gene expression and nucleotide metabolism. This is facilitated by a set of CMV gene products that target master regulators of G1/S progression such as cyclin E and A kinases, Rb-E2F transcription factors, p53-p21 checkpoint proteins, the APC/C ubiquitin ligase, and the nucleotide hydrolase SAMHD1. While the major themes of cell cycle regulation are well conserved between human and murine CMVs (HCMV and MCMV), there are considerable differences at the level of viral cell cycle effectors and their mechanisms of action. Furthermore, both viruses have evolved unique mechanisms to sense the host cell cycle state and modulate the infection program accordingly. This review provides an overview of conserved and divergent features of G1/S control by MCMV and HCMV.
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Chan B, Arapović M, Masters LL, Rwandamuiye F, Jonjić S, Smith LM, Redwood AJ. The m15 Locus of Murine Cytomegalovirus Modulates Natural Killer Cell Responses to Promote Dissemination to the Salivary Glands and Viral Shedding. Pathogens 2021; 10:pathogens10070866. [PMID: 34358016 PMCID: PMC8308470 DOI: 10.3390/pathogens10070866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 11/16/2022] Open
Abstract
As the largest herpesviruses, the 230 kb genomes of cytomegaloviruses (CMVs) have increased our understanding of host immunity and viral escape mechanisms, although many of the annotated genes remain as yet uncharacterised. Here we identify the m15 locus of murine CMV (MCMV) as a viral modulator of natural killer (NK) cell immunity. We show that, rather than discrete transcripts from the m14, m15 and m16 genes as annotated, there are five 3′-coterminal transcripts expressed over this region, all utilising a consensus polyA tail at the end of the m16 gene. Functional inactivation of any one of these genes had no measurable impact on viral replication. However, disruption of all five transcripts led to significantly attenuated dissemination to, and replication in, the salivary glands of multiple strains of mice, but normal growth during acute infection. Disruption of the m15 locus was associated with heightened NK cell responses, including enhanced proliferation and IFNγ production. Depletion of NK cells, but not T cells, rescued salivary gland replication and viral shedding. These data demonstrate the identification of multiple transcripts expressed by a single locus which modulate, perhaps in a concerted fashion, the function of anti-viral NK cells.
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Affiliation(s)
- Baca Chan
- School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (B.C.); (L.L.M.); (F.R.); (L.M.S.)
- Institute of Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
| | - Maja Arapović
- Department for Histology and Embryology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (M.A.); (S.J.)
| | - Laura L. Masters
- School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (B.C.); (L.L.M.); (F.R.); (L.M.S.)
| | - Francois Rwandamuiye
- School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (B.C.); (L.L.M.); (F.R.); (L.M.S.)
| | - Stipan Jonjić
- Department for Histology and Embryology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (M.A.); (S.J.)
| | - Lee M. Smith
- School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (B.C.); (L.L.M.); (F.R.); (L.M.S.)
| | - Alec J. Redwood
- School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (B.C.); (L.L.M.); (F.R.); (L.M.S.)
- Institute of Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
- Correspondence: ; Tel.: +61-8-6151-0895
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Costa H, Xu X, Overbeek G, Vasaikar S, Patro CPK, Kostopoulou ON, Jung M, Shafi G, Ananthaseshan S, Tsipras G, Davoudi B, Mohammad AA, Lam H, Strååt K, Wilhelmi V, Shang M, Tegner J, Tong JC, Wong KT, Söderberg-Naucler C, Yaiw KC. Human cytomegalovirus may promote tumour progression by upregulating arginase-2. Oncotarget 2018; 7:47221-47231. [PMID: 27363017 PMCID: PMC5216936 DOI: 10.18632/oncotarget.9722] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 05/14/2016] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Both arginase (ARG2) and human cytomegalovirus (HCMV) have been implicated in tumorigenesis. However, the role of ARG2 in the pathogenesis of glioblastoma (GBM) and the HCMV effects on ARG2 are unknown. We hypothesize that HCMV may contribute to tumorigenesis by increasing ARG2 expression. RESULTS ARG2 promotes tumorigenesis by increasing cellular proliferation, migration, invasion and vasculogenic mimicry in GBM cells, at least in part due to overexpression of MMP2/9. The nor-NOHA significantly reduced migration and tube formation of ARG2-overexpressing cells. HCMV immediate-early proteins (IE1/2) or its downstream pathways upregulated the expression of ARG2 in U-251 MG cells. Immunostaining of GBM tissue sections confirmed the overexpression of ARG2, consistent with data from subsets of Gene Expression Omnibus. Moreover, higher levels of ARG2 expression tended to be associated with poorer survival in GBM patient by analyzing data from TCGA. METHODS The role of ARG2 in tumorigenesis was examined by proliferation-, migration-, invasion-, wound healing- and tube formation assays using an ARG2-overexpressing cell line and ARG inhibitor, N (omega)-hydroxy-nor-L-arginine (nor-NOHA) and siRNA against ARG2 coupled with functional assays measuring MMP2/9 activity, VEGF levels and nitric oxide synthase activity. Association between HCMV and ARG2 were examined in vitro with 3 different GBM cell lines, and ex vivo with immunostaining on GBM tissue sections. The viral mechanism mediating ARG2 induction was examined by siRNA approach. Correlation between ARG2 expression and patient survival was extrapolated from bioinformatics analysis on data from The Cancer Genome Atlas (TCGA). CONCLUSIONS ARG2 promotes tumorigenesis, and HCMV may contribute to GBM pathogenesis by upregulating ARG2.
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Affiliation(s)
- Helena Costa
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Xinling Xu
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Gitta Overbeek
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Suhas Vasaikar
- Unit of Computational Medicine, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - C Pawan K Patro
- Social & Cognitive Computing Department, Institute of High Performance Computing, Agency for Science, Technology and Research, Singapore
| | - Ourania N Kostopoulou
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Masany Jung
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Gowhar Shafi
- Department of Genomics and Bioinformatics, Positive Bioscience, Mumbai, India
| | - Sharan Ananthaseshan
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Giorgos Tsipras
- Unit of Computational Medicine, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Belghis Davoudi
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Abdul-Aleem Mohammad
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Hoyin Lam
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden.,Present affiliation: Division of Cancer Studies, King's College London, London, UK
| | - Klas Strååt
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden.,Division of Gene Technology, School of Biotechnology, Science for Life Laboratory, Royal Institute of Technology (KTH), Solna, Sweden
| | - Vanessa Wilhelmi
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Mingmei Shang
- Unit of Computational Medicine, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Jesper Tegner
- Unit of Computational Medicine, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Joo Chuan Tong
- Social & Cognitive Computing Department, Institute of High Performance Computing, Agency for Science, Technology and Research, Singapore
| | - Kum Thong Wong
- Department of Pathology, Faculty of Medicine, University of Malaya, Malaysia
| | - Cecilia Söderberg-Naucler
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Koon-Chu Yaiw
- Cell and Molecular Immunology, Department of Medicine, Center for Molecular Medicine, Unit for Experimental Cardiovascular Research and Department of Neurology, Karolinska Institutet, Stockholm, Sweden
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Huang C, Wang H, Wu S, Chang H, Liu L, Peng B, Fang F, Chen Z. Comparison of multiple DNA vaccines for protection against cytomegalovirus infection in BALB/c mice. Virol J 2014; 11:104. [PMID: 24898886 PMCID: PMC4073173 DOI: 10.1186/1743-422x-11-104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 05/23/2014] [Indexed: 11/23/2022] Open
Abstract
Background Human cytomegalovirus (HCMV) causes serious HCMV-related diseases in immunocompromised people. Vaccination is the most effective measure to control infection with the pathogen, yet no vaccine has been licensed till now. We performed a head-to-head comparison of the protective abilities of multiple DNA vaccines in murine model of murine cytomegalovirus (MCMV) infection. Methods Five DNA vaccines were constructed. Four encoding MCMV proteins gp34 (m04), p65 (M84), DNA helicase (M105), and immediate-early 1 protein pp89 (IE-1) , respectively, which were reported to induce CD8+ T cell responses, were compared with the one expressing gB (M55), the neutralizing antibody target antigen, for immune protection in BALB/c mice. Mice were immunized with these DNA vaccines 1 to 4 times via intramuscular injection followed by electroporation, and were subsequently infected with a lethal dose (3 × LD50) of highly virulent SG-MCMV. Specific antibodies and IFN-γ secreting splenocytes were detected by immunoblotting and ELISPOT, respectively. Protective abilities in mice provided by the vaccines were evaluated by residual virus titers in organs, survival rate and weight loss. Results These DNA vaccines, especially m04, M84 and IE-1, could effectively reduce the virus loads in salivary glands and spleens of mice, but they couldn’t completely clear the residual virus. Survival rates of 100% in mice after a lethal dose of MCMV infection could be reached by more than one dose of M84 vaccine or two doses of m04 or IE-1 vaccine. Immunization with M55 or M105 DNA at four doses offered mice only 62.5% survival rate after the lethal challenge. Conclusions The study demonstrated that DNA vaccines could effectively afford mice protection against infection with a highly virulent MCMV and that the protection offered by induced CD8+ T cell immunity might be superior to that by gB-specific antibodies. These results are valuable references for development and application of HCMV vaccines.
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Affiliation(s)
| | | | | | | | | | | | - Fang Fang
- College of Life Sciences, Hunan Normal University, Changsha 410081, Hunan, China.
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Malouli D, Hansen SG, Nakayasu ES, Marshall EE, Hughes CM, Ventura AB, Gilbride RM, Lewis MS, Xu G, Kreklywich C, Whizin N, Fischer M, Legasse AW, Viswanathan K, Siess D, Camp DG, Axthelm MK, Kahl C, DeFilippis VR, Smith RD, Streblow DN, Picker LJ, Früh K. Cytomegalovirus pp65 limits dissemination but is dispensable for persistence. J Clin Invest 2014; 124:1928-44. [PMID: 24691437 DOI: 10.1172/jci67420] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 02/13/2014] [Indexed: 11/17/2022] Open
Abstract
The most abundantly produced virion protein in human cytomegalovirus (HCMV) is the immunodominant phosphoprotein 65 (pp65), which is frequently included in CMV vaccines. Although it is nonessential for in vitro CMV growth, pp65 displays immunomodulatory functions that support a potential role in primary and/or persistent infection. To determine the contribution of pp65 to CMV infection and immunity, we generated a rhesus CMV lacking both pp65 orthologs (RhCMVΔpp65ab). While deletion of pp65ab slightly reduced growth in vitro and increased defective particle formation, the protein composition of secreted virions was largely unchanged. Interestingly, pp65 was not required for primary and persistent infection in animals. Immune responses induced by RhCMVΔpp65ab did not prevent reinfection with rhesus CMV; however, reinfection with RhCMVΔUS2-11, which lacks viral-encoded MHC-I antigen presentation inhibitors, was prevented. Unexpectedly, induction of pp65b-specific T cells alone did not protect against RhCMVΔUS2-11 challenge, suggesting that T cells targeting multiple CMV antigens are required for protection. However, pp65-specific immunity was crucial for controlling viral dissemination during primary infection, as indicated by the marked increase of RhCMVΔpp65ab genome copies in CMV-naive, but not CMV-immune, animals. Our data provide rationale for inclusion of pp65 into CMV vaccines but also demonstrate that pp65-induced T cell responses alone do not recapitulate the protective effect of natural infection.
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Blalock EL, Chien H, Dix RD. Murine cytomegalovirus downregulates interleukin-17 in mice with retrovirus-induced immunosuppression that are susceptible to experimental cytomegalovirus retinitis. Cytokine 2013; 61:862-75. [PMID: 23415673 DOI: 10.1016/j.cyto.2013.01.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 01/06/2013] [Accepted: 01/07/2013] [Indexed: 12/31/2022]
Abstract
Interleukin-17 (IL-17), a pro-inflammatory cytokine produced by CD4+ Th17 cells, has been associated with the pathogenesis of several autoimmune diseases including uveitis. The fate of IL-17 during HIV/AIDS, however, remains unclear, and a possible role for IL-17 in the pathogenesis of AIDS-related diseases has not been investigated. Toward these ends, we performed studies using a well-established animal model of experimental murine cytomegalovirus (MCMV) retinitis that develops in C57/BL6 mice with retrovirus-induced immunosuppression (MAIDS). After establishing baseline levels for IL-17 production in whole splenic cells of healthy mice, we observed a significant increase in IL-17 mRNA levels in whole splenic cells of mice with MAIDS of 4-weeks (MAIDS-4), 8-weeks (MAIDS-8), and 10-weeks (MAIDS-10) duration. In contrast, enriched populations of splenic CD4+ T cells, splenic macrophages, and splenic neutrophils exhibited a reproducible decrease in levels of IL-17 mRNA during MAIDS progression. To explore a possible role for IL-17 during the pathogenesis of MAIDS-related MCMV retinitis, we first demonstrated constitutive IL-17 expression in retinal photoreceptor cells of uninfected eyes of healthy mice. Subsequent studies, however, revealed a significant decrease in intraocular levels of IL-17 mRNA and protein in MCMV-infected eyes of MAIDS-10 mice during retinitis development. That MCMV infection might cause a remarkable downregulation of IL-17 production was supported further by the finding that systemic MCMV infection of healthy, MAIDS-4, or MAIDS-10 mice also significantly decreased IL-17 mRNA production by splenic CD4+ T cells. Based on additional studies using IL-10 -/- mice infected systemically with MCMV and IL-10 -/- mice with MAIDS infected intraocularly with MCMV, we propose that MCMV infection downregulates IL-17 production via stimulation of suppressor of cytokine signaling (SOCS)-3 and interleukin-10.
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Affiliation(s)
- Emily L Blalock
- Department of Biology, Viral Immunology Center, Georgia State University, Atlanta, GA 30303, United States
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Tsen SWD, Chapa T, Beatty W, Tsen KT, Yu D, Achilefu S. Inactivation of enveloped virus by laser-driven protein aggregation. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:128002. [PMID: 23224114 PMCID: PMC3518210 DOI: 10.1117/1.jbo.17.12.128002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ultrafast lasers in the visible and near-infrared range have emerged as a potential new method for pathogen reduction of blood products and pharmaceuticals. However, the mechanism of enveloped virus inactivation by this method is unknown. We report the inactivation as well as the molecular and structural effects caused by visible (425 nm) femtosecond laser irradiation on murine cytomegalovirus (MCMV), an enveloped, double-stranded DNA virus. Our results show that laser irradiation (1) caused a 5-log reduction in MCMV titer, (2) did not cause significant changes to the global structure of MCMV virions including membrane and capsid, as assessed by electron microscopy, (3) produced no evidence of double-strand breaks or crosslinking in MCMV genomic DNA, and (4) caused selective aggregation of viral capsid and tegument proteins. We propose a model in which ultrafast laser irradiation induces partial unfolding of viral proteins by disrupting hydrogen bonds and/or hydrophobic interactions, leading to aggregation of closely associated viral proteins and inactivation of the virus. These results provide new insight into the inactivation of enveloped viruses by visible femtosecond lasers at the molecular level, and help pave the way for the development of a new ultrafast laser technology for pathogen reduction.
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Affiliation(s)
- Shaw-Wei D. Tsen
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110
| | - Travis Chapa
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110
| | - Wandy Beatty
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110
| | - Kong-Thon Tsen
- Arizona State University, Department of Physics, Tempe, Arizona 85287
- Arizona State University, Center for Biophysics, Tempe, Arizona 85287
- Address correspondence to: Samuel Achilefu, Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110. Tel: 314-362-8599; Fax: 314-747-5191; E-mail: , or Kong-Thon Tsen, Arizona State University, Department of Physics, Tempe, Arizona 85287. Tel: 480-965-5206; Fax: 480-965-7954;
| | - Dong Yu
- Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110
| | - Samuel Achilefu
- Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110
- Washington University School of Medicine, Department of Biochemistry and Molecular Biophysics, St. Louis, Missouri 63110
- Washington University School of Medicine, Department of Biomedical Engineering, St. Louis, Missouri 63110
- Address correspondence to: Samuel Achilefu, Washington University School of Medicine, Department of Radiology, St. Louis, Missouri 63110. Tel: 314-362-8599; Fax: 314-747-5191; E-mail: , or Kong-Thon Tsen, Arizona State University, Department of Physics, Tempe, Arizona 85287. Tel: 480-965-5206; Fax: 480-965-7954;
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Properties of virion transactivator proteins encoded by primate cytomegaloviruses. Virol J 2009; 6:65. [PMID: 19473490 PMCID: PMC2693105 DOI: 10.1186/1743-422x-6-65] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 05/27/2009] [Indexed: 11/25/2022] Open
Abstract
Background Human cytomegalovirus (HCMV) is a betaherpesvirus that causes severe disease in situations where the immune system is immature or compromised. HCMV immediate early (IE) gene expression is stimulated by the virion phosphoprotein pp71, encoded by open reading frame (ORF) UL82, and this transactivation activity is important for the efficient initiation of viral replication. It is currently recognized that pp71 acts to overcome cellular intrinsic defences that otherwise block viral IE gene expression, and that interactions of pp71 with the cell proteins Daxx and ATRX are important for this function. A further property of pp71 is the ability to enable prolonged gene expression from quiescent herpes simplex virus type 1 (HSV-1) genomes. Non-human primate cytomegaloviruses encode homologs of pp71, but there is currently no published information that addresses their effects on gene expression and modes of action. Results The UL82 homolog encoded by simian cytomegalovirus (SCMV), strain Colburn, was identified and cloned. This ORF, named S82, was cloned into an HSV-1 vector, as were those from baboon, rhesus monkey and chimpanzee cytomegaloviruses. The use of an HSV-1 vector enabled expression of the UL82 homologs in a range of cell types, and permitted investigation of their abilities to direct prolonged gene expression from quiescent genomes. The results show that all UL82 homologs activate gene expression, and that neither host cell type nor promoter target sequence has major effects on these activities. Surprisingly, the UL82 proteins specified by non-human primate cytomegaloviruses, unlike pp71, did not direct long term expression from quiescent HSV-1 genomes. In addition, significant differences were observed in the intranuclear localization of the UL82 homologs, and in their effects on Daxx. Strikingly, S82 mediated the release of Daxx from nuclear domain 10 substructures much more rapidly than pp71 or the other proteins tested. All UL82 homologs stimulated the early release of ATRX from nuclear domain 10. Conclusion All of the UL82 homolog proteins analysed activated gene expression, but surprising differences in other aspects of their properties were revealed. The results provide new information on early events in infection with cytomegaloviruses.
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Differences between mouse and human cytomegalovirus interactions with their respective hosts at immediate early times of the replication cycle. Med Microbiol Immunol 2008; 197:241-9. [PMID: 18264718 DOI: 10.1007/s00430-008-0078-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Indexed: 12/29/2022]
Abstract
The promise of the mouse model of cytomegalovirus (CMV) research lies in a cost effective way to obtain significant data in in vivo settings. Keeping that promise requires a high degree of equivalency in the human and mouse virus. While genomic structure and many common proteins suggest that this system is appropriate to develop and test concepts in an organismal context, areas of difference have not been evaluated. Here we show that the major immediate early protein 1 (IE1) in MCMV binds the repressor Daxx suggesting that it serves a function performed by pp71 in HCMV. A Daxx binding pp71 equivalent at M82 could not be identified for MCMV. Differences in the mouse and human interferon upregulation of Daxx may have driven the need to have a Daxx-defeating function during reactivation, when pp71 is not present. The major immediate early protein 1 also differs in its chromatin binding properties between the two viruses. MCMV IE1 does not bind to chromatin, but HCMV IE1 does. It remains unclear whether this difference is functionally significant. The HCMV major immediate early protein 2 and its MCMV equivalent IE3 differ in their effect on the cell cycle; HCMV IE2 blocks the cell cycle, but MCMV IE3 does not, allowing MCMV to spread in infected mouse cells by cell division with continued expression of the major transactivating viral proteins. Actively transcribing genomes inducing immediate transcript environments are usually silenced and diminish during cell cycle progression. However, a recognizable desilencing and increase in immediate transcript environments takes place immediately after mitosis in MCMV infected cells. This raises the possibility that desilencing happens during tissue transplantation, wound healing, or other injury where cells are induced to proliferate.
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Morello CS, Kelley LA, Munks MW, Hill AB, Spector DH. DNA immunization using highly conserved murine cytomegalovirus genes encoding homologs of human cytomegalovirus UL54 (DNA polymerase) and UL105 (helicase) elicits strong CD8 T-cell responses and is protective against systemic challenge. J Virol 2007; 81:7766-75. [PMID: 17507492 PMCID: PMC1933361 DOI: 10.1128/jvi.00633-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2007] [Accepted: 05/04/2007] [Indexed: 01/03/2023] Open
Abstract
Human cytomegalovirus (HCMV) establishes a lifelong infection with the potential for reinfection or viral transmission even in the presence of strong and diverse CD8 T-lymphocyte responses. This suggests that the CMVs skew the host T-cell response in order to favor viral persistence. In this study, we hypothesized that the essential, nonstructural proteins that are highly conserved among the CMVs may represent a novel class of T-cell targets for vaccine-mediated protection due to their requirements for expression and sequence stability, but that the observed subdominance of these antigens in the CMV-infected host results from the virus limiting the T-cell responses to otherwise-protective specificities. We found that DNA immunization of mice with the murine CMV (MCMV) homologs of HCMV DNA polymerase (M54) or helicase (M105) was protective against virus replication in the spleen following systemic challenge, with the protection level elicited by the M54 DNA being comparable to that of DNA expressing the immunodominant IE1 (pp89). Intracellular gamma interferon staining of CD8 T cells from mice immunized with either the M54 or M105 DNAs showed strong primary responses that recalled rapidly after viral challenge. M54- and M105-specific CD8 T cells were detected after the primary MCMV infection, but their levels were not consistently above the background level. The conserved, essential proteins of the CMVs thus represent a novel class of CD8 T-cell targets that may contribute to a successful HCMV vaccine strategy.
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Affiliation(s)
- Christopher S Morello
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093-0712, USA
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12
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Schleiss MR, Heineman TC. Progress toward an elusive goal: current status of cytomegalovirus vaccines. Expert Rev Vaccines 2006; 4:381-406. [PMID: 16026251 DOI: 10.1586/14760584.4.3.381] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although infection with human cytomegalovirus (CMV) is ubiquitous and generally asymptomatic in most individuals, certain patient populations are at high risk for CMV-associated disease. These include HIV-infected individuals with AIDS, transplant patients, and newborn infants with congenital CMV infection. Immunity to CMV infection, both in the transplant setting and among women of childbearing age, plays a vital role in the control of CMV-induced injury and disease. Although immunity induced by CMV infection is not completely protective against reinfection, there is nevertheless a sound basis on which to believe that vaccination could help control CMV disease in high-risk patient populations. Evidence from several animal models of CMV infection indicates that a variety of vaccine strategies are capable of inducing immune responses sufficient to protect against CMV-associated illness following viral challenge. Vaccination has also proven effective in improving pregnancy outcomes following CMV challenge of pregnant guinea pigs, providing a 'proof-of-principle' relevant to human clinical trials of CMV vaccines. Although there are no licensed vaccines currently available for human CMV, progress toward this goal has been made, as evidenced by ongoing clinical trial testing of a number of immunization strategies. CMV vaccines currently in various stages of preclinical and clinical testing include: protein subunit vaccines; DNA vaccines; vectored vaccines using viral vectors, such as attenuated pox- and alphaviruses; peptide vaccines; and live attenuated vaccines. This review summarizes some of the obstacles that must be overcome in development of a CMV vaccine, and provides an overview of the current state of preclinical and clinical trial evaluation of vaccines for this important public health problem.
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Affiliation(s)
- Mark R Schleiss
- University of Minnesota School of Medicine, 420 Delaware Street SE, MMC 296, Minneapolis, MN 55455, USA.
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13
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Munks MW, Gold MC, Zajac AL, Doom CM, Morello CS, Spector DH, Hill AB. Genome-wide analysis reveals a highly diverse CD8 T cell response to murine cytomegalovirus. THE JOURNAL OF IMMUNOLOGY 2006; 176:3760-6. [PMID: 16517745 DOI: 10.4049/jimmunol.176.6.3760] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Human CMV establishes a lifelong latent infection in the majority of people worldwide. Although most infections are asymptomatic, immunocompetent hosts devote an extraordinary amount of immune resources to virus control. To increase our understanding of CMV immunobiology in an animal model, we used a genomic approach to comprehensively map the C57BL/6 CD8 T cell response to murine CMV (MCMV). Responses to 27 viral proteins were detectable directly ex vivo, the most diverse CD8 T cell response yet described within an individual animal. Twenty-four peptide epitopes were mapped from 18 Ags, which together account for most of the MCMV-specific response. Most Ags were from genes expressed at early times, after viral genes that interfere with Ag presentation are expressed, consistent with the hypothesis that the CD8 T cell response to MCMV is largely driven by cross-presented Ag. Titration of peptide epitopes in a direct ex vivo intracellular cytokine staining assay revealed a wide range of functional avidities, with no obvious correlation between functional avidity and the strength of the response. The immunodominance hierarchy varied only slightly between mice and between experiments. However, H-2(b)-expressing mice with different genetic backgrounds responded preferentially to different epitopes, indicating that non-MHC-encoded factors contribute to immunodominance in the CD8 T cell response to MCMV.
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Affiliation(s)
- Michael W Munks
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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14
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Abstract
Published work (D. J. McGeoch, Nucleic Acids Res. 18:4105-4110, 1990; J. E. McGeehan, N. W. Depledge, and D. J. McGeoch, Curr. Protein Peptide Sci. 2:325-333, 2001) has indicated that evolution of dUTPase in the class of herpesviruses that infect mammals and birds involved capture of a host gene followed by a duplication event that resulted in a coding region comprising two fused dUTPase domains. Some of the conserved residues required for enzyme activity were then lost, resulting in a dUTPase containing a single active site with different elements contributed by each half of the protein. Further conserved residues were lost in one subfamily (the Betaherpesvirinae), yielding a protein that is related to herpesvirus dUTPases but has a different and as yet unrecognized function. Evidence from sequence similarities and structural predictions now indicates that several additional genes were derived from the herpesvirus dUTPase gene, probably by duplication. These are UL31, UL82, UL83, and UL84 in human cytomegalovirus (and counterparts in other members of the Betaherpesvirinae) and ORF10 and ORF11 in human herpesvirus 8 (and counterparts in other members of the Gammaherpesvirinae). The findings clarify the evolutionary history of these genes and provide novel insights for structural and functional studies.
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Affiliation(s)
- Andrew J Davison
- MRC Virology Unit, Institute of Virology, University of Glasgow, UK.
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15
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Morello CS, Ye M, Hung S, Kelley LA, Spector DH. Systemic priming-boosting immunization with a trivalent plasmid DNA and inactivated murine cytomegalovirus (MCMV) vaccine provides long-term protection against viral replication following systemic or mucosal MCMV challenge. J Virol 2005; 79:159-75. [PMID: 15596812 PMCID: PMC538742 DOI: 10.1128/jvi.79.1.159-175.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Accepted: 08/23/2004] [Indexed: 11/20/2022] Open
Abstract
We previously demonstrated that vaccination of BALB/c mice with a pool of 13 plasmid DNAs (pDNAs) expressing murine cytomegalovirus (MCMV) genes followed by formalin-inactivated MCMV (FI-MCMV) resulted in complete protection against viral replication in the spleen and salivary glands following sublethal intraperitoneal (i.p.) challenge. Here, we found that following intranasal (i.n.) challenge, titers of virus in the lungs of the immunized mice were reduced approximately 1,000-fold relative to those for mock-immunized controls. We next sought to extend these results and to determine whether similar protection levels could be achieved by priming with a pool of three pDNAs containing three key plasmids (IE1, M84, and gB). We found that the three-pDNA priming elicited IE1- and M84-p65-specific CD8+ T lymphocytes and, following FI-MCMV boost, high levels of virion-specific immunoglobulin G (IgG) and virus-neutralizing antibodies. When mice were i.n. challenged 4 months after the last boost, titers of virus in the lungs of immunized mice were reduced 1,000- to 2,000-fold from those for controls during the peak of viral replication. Additionally, titers of virus were either at or below the detection limits for the salivary glands, liver, and spleen of the majority of the immunized mice. Following sublethal i.p. challenge, virus was undetectable in all of the above target organs of the immunized mice. Virion-specific IgA in the lungs was consistently detected by day 6 post-i.n. challenge for the immunized mice and by day 14 for controls. These results demonstrate the immunity and high levels of protection of the priming-boosting vaccination against both systemic and mucosal challenge.
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Affiliation(s)
- Christopher S Morello
- Section of Molecular Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla, California 92093-0366, USA
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16
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Kattenhorn LM, Mills R, Wagner M, Lomsadze A, Makeev V, Borodovsky M, Ploegh HL, Kessler BM. Identification of proteins associated with murine cytomegalovirus virions. J Virol 2004; 78:11187-97. [PMID: 15452238 PMCID: PMC521832 DOI: 10.1128/jvi.78.20.11187-11197.2004] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Proteins associated with the murine cytomegalovirus (MCMV) viral particle were identified by a combined approach of proteomic and genomic methods. Purified MCMV virions were dissociated by complete denaturation and subjected to either separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in-gel digestion or treated directly by in-solution tryptic digestion. Peptides were separated by nanoflow liquid chromatography and analyzed by tandem mass spectrometry (LC-MS/MS). The MS/MS spectra obtained were searched against a database of MCMV open reading frames (ORFs) predicted to be protein coding by an MCMV-specific version of the gene prediction algorithm GeneMarkS. We identified 38 proteins from the capsid, tegument, glycoprotein, replication, and immunomodulatory protein families, as well as 20 genes of unknown function. Observed irregularities in coding potential suggested possible sequence errors in the 3'-proximal ends of m20 and M31. These errors were experimentally confirmed by sequencing analysis. The MS data further indicated the presence of peptides derived from the unannotated ORFs ORF(c225441-226898) (m166.5) and ORF(105932-106072). Immunoblot experiments confirmed expression of m166.5 during viral infection.
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Affiliation(s)
- Lisa M Kattenhorn
- Pathology Functional Proteomics Center, Department of Pathology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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17
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Ye M, Morello CS, Spector DH. Multiple epitopes in the murine cytomegalovirus early gene product M84 are efficiently presented in infected primary macrophages and contribute to strong CD8+-T-lymphocyte responses and protection following DNA immunization. J Virol 2004; 78:11233-45. [PMID: 15452242 PMCID: PMC521820 DOI: 10.1128/jvi.78.20.11233-11245.2004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously demonstrated that after vaccination of BALB/c mice with DNA encoding murine cytomegalovirus (MCMV) IE1 or M84, a similar level of protection against MCMV infection was achieved. However, the percentage of antigen-specific CD8(+) T cells elicited by IE1 was higher than that by M84 as measured by intracellular cytokine staining when splenocytes were stimulated with an epitope peptide (M. Ye at al., J. Virol. 76:2100-2112, 2002). We show here that after DNA vaccination with M84, a higher percentage of M84-specific CD8(+) T cells was detected when splenocytes were stimulated with J774 cells expressing full-length M84. When the defined M84 epitope 297-305 was deleted, the mutant DNA vaccine was still protective against MCMV replication and induced strong M84-specific CD8(+)-T-cell responses. The M84 gene was subsequently subcloned into three fragments encoding overlapping protein fragments. When mice were immunized with each of the M84 subfragment DNAs, at least two additional protective CD8(+)-T-cell epitopes were detected. In contrast to strong responses after DNA vaccination, M84-specific CD8(+)-T-cell responses were poorly induced during MCMV infection. The weak M84-specific response after MCMV infection was not due to poor antigen presentation in antigen-presenting cells, since both J774 macrophages and primary peritoneal macrophages infected with MCMV in vitro were able to efficiently and constitutively present M84-specific epitopes starting at the early phase of infection. These results indicate that antigen presentation by macrophages is not sufficient for M84-specific CD8(+)-T-cell responses during MCMV infection.
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Affiliation(s)
- Ming Ye
- Pacific Hall, Room 1224A, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0366, USA
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18
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McGregor A, Liu F, Schleiss MR. Molecular, biological, and in vivo characterization of the guinea pig cytomegalovirus (CMV) homologs of the human CMV matrix proteins pp71 (UL82) and pp65 (UL83). J Virol 2004; 78:9872-89. [PMID: 15331722 PMCID: PMC515002 DOI: 10.1128/jvi.78.18.9872-9889.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We recently identified the genes encoding the guinea pig cytomegalovirus (GPCMV) homologs of the upper and lower matrix proteins of human CMV, pp71 (UL82) and pp65 (UL83), which we designated GP82 and GP83, respectively. Transient-expression studies with a GP82 plasmid demonstrated that the encoded protein targets the nucleus and that the infectivity and plaquing efficiency of cotransfected GPCMV viral DNA was enhanced by GP82. The transactivation function of GP82 was not limited to GPCMV, but was also observed for a heterologous virus, herpes simplex virus type 1 (HSV-1). This was confirmed by its ability to complement the growth of an HSV-1 VP16 transactivation-defective mutant virus in an HSV viral DNA cotransfection assay. Study of a GP82 "knockout" virus (and its attendant rescuant), generated on a GPCMV bacterial artificial chromosome construct, confirmed the essential nature of the gene. Conventional homologous recombination was used to generate a GP83 mutant to examine the role of GP83 in the viral life cycle. Comparison of the one-step growth kinetics of the GP83 mutant (vAM409) and wild-type GPCMV indicated that GP83 protein is not required for viral replication in tissue culture. The role of GP83 in vivo was examined by comparing the pathogenesis of wild-type GPCMV, vAM409, and a control virus, vAM403, in guinea pigs. The vAM409 mutant was significantly attenuated for dissemination in immunocompromised strain 2 guinea pigs, suggesting that the GP83 protein is essential for full pathogenicity in vivo.
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Affiliation(s)
- Alistair McGregor
- Division of Infectious Diseases, Children's Hospital Medical Center Research Foundation, University of Cincinnati, OH 45229, USA
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19
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Tam A, Zhu J, Hai R, Haghjoo E, Tong T, Zhan X, Lu S, Liu F. Murine cytomegalovirus with a transposon insertional mutation at open reading frame M35 is defective in growth in vivo. J Virol 2003; 77:7746-55. [PMID: 12829814 PMCID: PMC161956 DOI: 10.1128/jvi.77.14.7746-7755.2003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We had previously constructed a pool of murine cytomegalovirus (MCMV) mutants that contained a Tn3-based transposon sequence randomly inserted in the viral genome. In the study reported here, one of the mutants, RvM35, which contains the transposon insertion at open reading frame M35, was characterized both in vitro in tissue cultures and in immunocompetent Balb/c and immunodeficient SCID mice. Our results provide the first direct evidence to suggest that M35 is not essential for viral replication in vitro in NIH 3T3 cells. Compared to the wild-type strain and a rescued virus that restored the M35 region, the viral mutant was attenuated in growth in both the intraperitoneally infected Balb/c and SCID mice. At 21 days postinfection, the titers of the mutant in the salivary glands, lungs, spleens, livers, and kidneys of the SCID mice were lower than the titers of the wild-type Smith strain and the rescued virus by 50,000-, 100-, 10-, 100-, and 50-fold, respectively. Moreover, the growth of RvM35 is severely attenuated in the salivary glands. The virulence of the mutant virus also appears to be attenuated, because no death was observed in SCID mice infected with RvM35 until 35 days postinfection, while all the animals infected with the wild-type and rescued viruses died 27 days postinfection. Our results suggest that M35 is important for MCMV virulence in killing SCID mice and is required for optimal viral growth in vivo, including in the salivary glands.
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Affiliation(s)
- Ada Tam
- Division of Infectious Diseases, School of Public Health, University of California-Berkeley, Berkeley, CA 94720, USA
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20
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Morello CS, Ye M, Spector DH. Development of a vaccine against murine cytomegalovirus (MCMV), consisting of plasmid DNA and formalin-inactivated MCMV, that provides long-term, complete protection against viral replication. J Virol 2002; 76:4822-35. [PMID: 11967299 PMCID: PMC136169 DOI: 10.1128/jvi.76.10.4822-4835.2002] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2001] [Accepted: 02/05/2002] [Indexed: 01/02/2023] Open
Abstract
We previously demonstrated that immunization of mice with plasmid DNAs (pDNAs) expressing the murine cytomegalovirus (MCMV) genes IE1-pp89 and M84 provided synergistic protection against sublethal viral challenge, while immunization with plasmids expressing putative virion proteins provided no or inconsistent protection. In this report, we sought to augment protection by increasing the breadth of the immune response. We identified another MCMV gene (m04 encoding gp34) that provided strong and consistent protection against viral replication in the spleen. We also found that immunization with a DNA pool containing 10 MCMV genes that individually were nonprotective elicited reproducible protection against low to intermediate doses of challenge virus. Moreover, inclusion of these plasmids into a mixture with gp34, pp89, and M84 DNAs provided even greater protection than did coimmunization with pp89 and M84. The highest level of protection was achieved by immunization of mice with the pool of 13 pDNAs, followed by formalin-inactivated MCMV (FI-MCMV). Immunization with FI-MCMV elicited neutralizing antibodies against salivary gland-derived MCMV, and of greatest importance, mice immunized with both the combined pDNA pool and FI-MCMV had undetectable levels of virus in the spleen and salivary glands after challenge. Intracellular cytokine staining of splenocytes from pDNA- and FI-MCMV-immunized mice showed that pDNA immunization elicited high levels of pp89- and M83-specific CD8(+) T cells, whereas both pDNA and FI-MCMV immunizations generated strong CD8(+)-T-cell responses against virion-associated antigens. Taken together, these results show that immunization with pDNA and inactivated virus provides strong antibody and cell-mediated immunity against CMV infection.
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Affiliation(s)
- Christopher S Morello
- Molecular Biology Section, Division of Biology, University of California, San Diego, La Jolla, California 92093-0366, USA
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21
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Ye M, Morello CS, Spector DH. Strong CD8 T-cell responses following coimmunization with plasmids expressing the dominant pp89 and subdominant M84 antigens of murine cytomegalovirus correlate with long-term protection against subsequent viral challenge. J Virol 2002; 76:2100-12. [PMID: 11836387 PMCID: PMC153826 DOI: 10.1128/jvi.76.5.2100-2112.2002] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2001] [Accepted: 12/03/2001] [Indexed: 11/20/2022] Open
Abstract
We previously showed that intradermal immunization with plasmids expressing the murine cytomegalovirus (MCMV) protein IE1-pp89 or M84 protects against viral challenge and that coimmunization has a synergistic protective effect (C. S. Morello, L. D. Cranmer, and D. H. Spector, J. Virol. 74:3696-3708, 2000). Using an intracellular gamma interferon cytokine staining assay, we have now characterized the CD8+ T-cell response after DNA immunization with pp89, M84, or pp89 plus M84. The pp89- and M84-specific CD8+ T-cell responses peaked rapidly after three immunizations. DNA immunization and MCMV infection generated similar levels of pp89-specific CD8+ T cells. In contrast, a significantly higher level of M84-specific CD8+ T cells was elicited by DNA immunization than by MCMV infection. Fusion of ubiquitin to pp89 enhanced the CD8+ T-cell response only under conditions where vaccination was suboptimal. Three immunizations with either pp89, M84, or pp89 plus M84 DNA also provided significant protection against MCMV infection for at least 6 months, with the best protection produced by coimmunization. A substantial percentage of antigen-specific CD8+ T cells remained detectable, and they responded rapidly to the MCMV challenge. These results underscore the importance of considering antigens that do not appear to be highly immunogenic during infection as DNA vaccine candidates.
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Affiliation(s)
- Ming Ye
- Molecular Biology Section, Division of Biology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0366, USA
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22
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Holtappels R, Grzimek NKA, Thomas D, Reddehase MJ. Early gene m18, a novel player in the immune response to murine cytomegalovirus. J Gen Virol 2002; 83:311-316. [PMID: 11807223 DOI: 10.1099/0022-1317-83-2-311] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The identification of all antigenic peptides encoded by a pathogen, its T cell 'immunome', is a research aim for rational vaccine design. Screening of proteome-spanning peptide libraries or computational prediction is used to identify antigenic peptides recognized by CD8 T cells. Based on their high coding capacity, cytomegaloviruses (CMVs) could specify numerous antigenic peptides. Yet, current evidence indicates that the memory CD8 T cell response in a given haplotype is actually focused on a few viral proteins. CMVs actively interfere with antigen processing and presentation by the expression of immune evasion proteins. In the case of murine CMV (mCMV), these proteins are effectual in the early (E) phase of the virus replication cycle and should thus preclude the presentation of peptides derived from E proteins. Notably, the m18 gene is here added to a growing list of mCMV E genes that encode antigenic peptides in spite of the E phase immune evasion strategies of the virus.
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Affiliation(s)
- Rafaela Holtappels
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany1
| | - Natascha K A Grzimek
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany1
| | - Doris Thomas
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany1
| | - Matthias J Reddehase
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany1
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23
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Holtappels R, Podlech J, Grzimek NK, Thomas D, Pahl-Seibert MF, Reddehase MJ. Experimental preemptive immunotherapy of murine cytomegalovirus disease with CD8 T-cell lines specific for ppM83 and pM84, the two homologs of human cytomegalovirus tegument protein ppUL83 (pp65). J Virol 2001; 75:6584-600. [PMID: 11413326 PMCID: PMC114382 DOI: 10.1128/jvi.75.14.6584-6600.2001] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CD8 T cells are the principal antiviral effectors controlling cytomegalovirus (CMV) infection. For human CMV, the virion tegument protein ppUL83 (pp65) has been identified as a source of immunodominant peptides and is regarded as a candidate for cytoimmunotherapy and vaccination. Two sequence homologs of ppUL83 are known for murine CMV, namely the virion protein ppM83 (pp105) expressed late in the viral replication cycle and the nonstructural protein pM84 (p65) expressed in the early phase. Here we show that ppM83, unlike ppUL83, is not delivered into the antigen presentation pathway after virus penetration before or in absence of viral gene expression, while other virion proteins of murine CMV are processed along this route. In cytokine secretion-based assays, ppM83 and pM84 appeared to barely contribute to the acute immune response and to immunological memory. Specifically, the frequencies of M83 and M84 peptide-specific CD8 T cells were low and undetectable, respectively. Nonetheless, in a murine model of cytoimmunotherapy of lethal CMV disease, M83 and M84 peptide-specific cytolytic T-cell lines proved to be highly efficient in resolving productive infection in multiple organs of cell transfer recipients. These findings demonstrate that proteins which fail to prime a quantitatively dominant immune response can nevertheless represent relevant antigens in the effector phase. We conclude that quantitative and qualitative immunodominance are not necessarily correlated. As a consequence of these findings, there is no longer a rationale for considering T-cell abundance as the key criterion for choosing specificities to be included in immunotherapy and immunoprophylaxis of CMV disease and of viral infections in general.
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Affiliation(s)
- R Holtappels
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany
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24
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Bahr U, Darai G. Analysis and characterization of the complete genome of tupaia (tree shrew) herpesvirus. J Virol 2001; 75:4854-70. [PMID: 11312357 PMCID: PMC114240 DOI: 10.1128/jvi.75.10.4854-4870.2001] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2000] [Accepted: 02/26/2001] [Indexed: 11/20/2022] Open
Abstract
The tupaia herpesvirus (THV) was isolated from spontaneously degenerating tissue cultures of malignant lymphoma, lung, and spleen cell cultures of tree shrews (Tupaia spp.). The determination of the complete nucleotide sequence of the THV strain 2 genome resulted in a 195,857-bp-long, linear DNA molecule with a G+C content of 66.5%. The terminal regions of the THV genome and the loci of conserved viral genes were found to be G+C richer. Furthermore, no large repetitive DNA sequences could be identified. This is in agreement with the previous classification of THV as the prototype species of herpesvirus genome group F. The search for potential coding regions resulted in the identification of 158 open reading frames (ORFs) regularly distributed on both DNA strands. Seventy-six out of the 158 ORFs code for proteins that are significantly homologous to known herpesvirus proteins. The highest homologies found were to primate and rodent cytomegaloviruses. Biological properties, protein homologies, the arrangement of conserved viral genes, and phylogenetic analysis revealed that THV is a member of the subfamily Betaherpesvirinae. The evolutionary lineages of THV and the cytomegaloviruses seem to have branched off from a common ancestor. In addition, it was found that the arrangements of conserved genes of THV and murine cytomegalovirus strain Smith, both of which are not able to form genomic isomers, are colinear with two different human cytomegalovirus (HCMV) strain AD169 genomic isomers that differ from each other in the orientation of the long unique region. The biological properties and the high degree of relatedness of THV to the mammalian cytomegaloviruses allow the consideration of THV as a model system for investigation of HCMV pathogenicity.
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Affiliation(s)
- U Bahr
- Institut für Medizinische Virologie, Universität Heidelberg, D-69120 Heidelberg, Germany
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25
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Abenes G, Lee M, Haghjoo E, Tong T, Zhan X, Liu F. Murine cytomegalovirus open reading frame M27 plays an important role in growth and virulence in mice. J Virol 2001; 75:1697-707. [PMID: 11160668 PMCID: PMC114079 DOI: 10.1128/jvi.75.4.1697-1707.2001] [Citation(s) in RCA: 30] [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
Using a Tn3-based transposon mutagenesis approach, we have generated a pool of murine cytomegalovirus (MCMV) mutants. In this study, one of the mutants, RvM27, which contained the transposon sequence at open reading frame M27, was characterized both in tissue culture and in immunocompetent BALB/c mice and immunodeficient SCID mice. Our results suggest that the M27 carboxyl-terminal sequence is dispensable for viral replication in vitro. Compared to the wild-type strain and a rescued virus that restored the M27 region, RvM27 was attenuated in growth in both BALB/c and SCID mice that were intraperitoneally infected with the viruses. Specifically, the titers of RvM27 in the salivary glands, lungs, spleens, livers, and kidneys of the infected SCID mice at 21 days postinfection were 50- to 500-fold lower than those of the wild-type virus and the rescued virus. Moreover, the virulence of the mutant virus appeared to be attenuated, because no deaths occurred among SCID mice infected with RvM27 for up to 37 days postinfection, while all the animals infected with the wild-type and rescued viruses died within 27 days postinfection. Our observations provide the first direct evidence to suggest that a disruption of M27 expression results in reduced viral growth and attenuated viral virulence in vivo in infected animals. Moreover, these results suggest that M27 is a viral determinant required for optimal MCMV growth and virulence in vivo and provide insight into the functions of the M27 homologues found in other animal and human CMVs as well as in other betaherpesviruses.
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Affiliation(s)
- G Abenes
- Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, California 94720, USA
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26
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Holtappels R, Pahl-Seibert MF, Thomas D, Reddehase MJ. Enrichment of immediate-early 1 (m123/pp89) peptide-specific CD8 T cells in a pulmonary CD62L(lo) memory-effector cell pool during latent murine cytomegalovirus infection of the lungs. J Virol 2000; 74:11495-503. [PMID: 11090146 PMCID: PMC112429 DOI: 10.1128/jvi.74.24.11495-11503.2000] [Citation(s) in RCA: 185] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2000] [Accepted: 09/19/2000] [Indexed: 11/20/2022] Open
Abstract
Interstitial cytomegalovirus (CMV) pneumonia is a clinically relevant complication in recipients of bone marrow transplantation (BMT). Recent data for a model of experimental syngeneic BMT and concomitant infection of BALB/c mice with murine CMV (mCMV) have documented the persistence of tissue-resident CD8 T cells after clearance of productive infection of the lungs (J. Podlech, R. Holtappels, M.-F. Pahl-Seibert, H.-P. Steffens, and M. J. Reddehase, J. Virol. 74:7496-7507, 2000). It was proposed that these cells represent antiviral "standby" memory cells whose functional role might be to help prevent reactivation of latent virus. The pool of pulmonary CD8 T cells was composed of two subsets defined by the T-cell activation marker L-selectin (CD62L): a CD62L(hi) subset of quiescent memory cells, and a CD62L(lo) subset of recently resensitized memory-effector cells. In this study, we have continued this line of investigation by quantitating CD8 T cells specific for the three currently published antigenic peptides of mCMV: peptide YPHFMPTNL processed from the immediate-early protein IE1 (pp89), and peptides YGPSLYRRF and AYAGLFTPL, derived from the early proteins m04 (gp34) and M84 (p65), respectively. IE1-specific CD8 T cells dominated in acute-phase pulmonary infiltrates and were selectively enriched in latently infected lungs. Notably, most IE1-specific CD8 T cells were found to belong to the CD62L(lo) subset representing memory-effector cells. This finding is in accordance with the interpretation that IE1-specific CD8 T cells are frequently resensitized during latent infection of the lungs and may thus be involved in the maintenance of mCMV latency.
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Affiliation(s)
- R Holtappels
- Institute for Virology, Johannes Gutenberg University, 55101 Mainz, Germany
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27
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Holtappels R, Thomas D, Reddehase MJ. Identification of a K(d)-restricted antigenic peptide encoded by murine cytomegalovirus early gene M84. J Gen Virol 2000; 81:3037-3042. [PMID: 11086134 DOI: 10.1099/0022-1317-81-12-3037] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The two sister cytomegaloviruses (CMVs), human and murine CMV, have both evolved immune evasion functions that interfere with the major histocompatibility complex class I (MHC-I) pathway of antigen processing and presentation and are effectual in the early (E) phase of virus gene expression. However, studies on murine CMV have shown that E-phase immune evasion is leaky. An E-phase protein involved in immune evasion, namely m04-gp34, was found to simultaneously account for an antigenic peptide presented by the MHC-I molecule D(d). Recent work has demonstrated the induction of protective immunity specific for the E-phase protein M84-p65, one of two murine CMV homologues of the human CMV matrix protein UL83-pp65. In this study, the identification of the MHC-I K(d)-restricted M84 peptide (297)AYAGLFTPL(305) is documented. This peptide is the third antigenic peptide described for murine CMV and the second that escapes immunosubversive mechanisms.
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Affiliation(s)
- Rafaela Holtappels
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany1
| | - Doris Thomas
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany1
| | - Matthias J Reddehase
- Institute for Virology, Johannes Gutenberg University, Hochhaus am Augustusplatz, 55101 Mainz, Germany1
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28
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Zhan X, Lee M, Xiao J, Liu F. Construction and characterization of murine cytomegaloviruses that contain transposon insertions at open reading frames m09 and M83. J Virol 2000; 74:7411-21. [PMID: 10906194 PMCID: PMC112261 DOI: 10.1128/jvi.74.16.7411-7421.2000] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A transposon derived from Escherichia coli Tn3 was introduced into the genome of murine cytomegalovirus (MCMV) to generate a pool of viral mutants, including two recombinant viruses that contained the transposon sequence within open reading frames m09 and M83. Our studies provide the first direct evidence to suggest that m09 is not essential for viral replication in mouse NIH 3T3 cells. Studies in cultured cells and in both BALB/c-Byj and CB17 severe combined immunodeficient (SCID) mice indicated that the transposon insertion is stable during viral propagation both in vitro and in vivo. Moreover, the virus that contained the insertion mutation in m09 exhibited a titer similar to that of the wild-type virus in the salivary glands, lungs, livers, spleens, and kidneys of both the BALB/c and SCID mice and was as virulent as the wild-type virus in killing the SCID mice when these animals were intraperitoneally infected with these viruses. These results suggest that m09 is dispensable for viral growth in these organs and that the presence of the transposon sequence in the viral genome does not significantly affect viral replication in vivo. In contrast, the virus that contained the insertion mutation in M83 exhibited a titer of at least 60-fold lower than that of the wild-type virus in the organs of the SCID mice and was attenuated in killing the SCID mice. These results demonstrate the utility of using the Tn3-based system as a mutagenesis approach for studying the function of MCMV genes in both immunocompetent and immunodeficient animals.
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Affiliation(s)
- X Zhan
- Program in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, California 94720, USA
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29
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Abstract
We have determined the complete genome sequence of the Maastricht strain of rat cytomegalovirus (RCMV). The RCMV genome has a length of 229,896 bp and is arranged as a single unique sequence flanked by 504-bp terminal direct repeats. RCMV was found to have counterparts of all but one of the open reading frames (ORFs) that are conserved between murine CMV (MCMV) and human CMV (HCMV). Like HCMV, RCMV lacks homologs of the genes belonging to the MCMV m02 glycoprotein gene family. However, RCMV contains 15 ORFs with homology to members of the MCMV m145 glycoprotein gene family. Four ORFs are predicted to encode homologs of host proteins; R33 and R78 both putatively encode G protein-coupled receptors, whereas r144 and r131 encode homologs of major histocompatibility class I heavy chains and CC chemokines, respectively. An intriguing feature of the RCMV genome is the presence of an ORF, r127, with similarity to the rep gene of parvoviruses as well as ORF U94 of human herpesvirus 6A (HHV-6A) and HHV-6B. Counterparts of these ORFs have not been found in the other sequenced herpesviruses.
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Affiliation(s)
- C Vink
- Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, University of Maastricht, 6202 AZ Maastricht, The Netherlands.
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30
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Morello CS, Cranmer LD, Spector DH. Suppression of murine cytomegalovirus (MCMV) replication with a DNA vaccine encoding MCMV M84 (a homolog of human cytomegalovirus pp65). J Virol 2000; 74:3696-708. [PMID: 10729145 PMCID: PMC111879 DOI: 10.1128/jvi.74.8.3696-3708.2000] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cytotoxic T-lymphocyte (CTL) response against the murine cytomegalovirus (MCMV) immediate-early gene 1 (IE1) 89-kDa phosphoprotein pp89 plays a major role in protecting BALB/c mice against the lethal effects of the viral infection. CTL populations specific to MCMV early-phase and structural antigens are also generated during infection, but the identities of these antigens and their relative contributions to overall immunity against MCMV are not known. We previously demonstrated that DNA vaccination with a pp89-expressing plasmid effectively generated a CTL response and conferred protection against infection (J. C. Gonzalez Armas, C. S. Morello, L. D. Cranmer, and D. H. Spector, J. Virol. 70:7921-7928, 1996). In this report, we have sought (i) to identify other viral antigens that contribute to immunity against MCMV and (ii) to determine whether the protective response is haplotype specific. DNA immunization was used to test the protective efficacies of plasmids encoding MCMV homologs of human cytomegalovirus (HCMV) tegument (M32, M48, M56, M82, M83, M69, and M99), capsid (M85 and M86), and nonstructural antigens (IE1-pp89 and M84). BALB/c (H-2(d)) and C3H/HeN (H-2(k)) mice were immunized by intradermal injection of either single plasmids or cocktails of up to four expression plasmids and then challenged with sublethal doses of virulent MCMV administered intraperitoneally. In this way, we identified a new viral gene product, M84, that conferred protection against viral replication in the spleens of BALB/c mice. M84 is expressed early in the infection and encodes a nonstructural protein that shares significant amino acid homology with the HCMV UL83-pp65 tegument protein, a major target of protective CTLs in humans. Specificity of the immune response to the M84 protein was confirmed by showing that immunization with pp89 DNA, but not M84 DNA, protected mice against subsequent infection with an MCMV deletion mutant lacking the M84 gene. The other MCMV genes tested did not generate a protective response even when mice were immunized with vaccinia viruses expressing the viral proteins. However, the M84 plasmid was protective when injected in combination with nonprotective plasmids, and coimmunization of BALB/c mice with pp89 and M84 provided a synergistic level of protection in the spleen. Viral titers in the salivary glands were also reduced, but not to the same extent as observed in the spleen, and the decrease was seen only when the BALB/c mice were immunized with pp89 plus M84 or with pp89 alone. The experiments with the C3H/HeN mice showed that the immunity conferred by DNA vaccination was haplotype dependent. In this strain of mice, only pp89 elicited a protective response as measured by a reduction in spleen titer. These results suggest that DNA immunization with the appropriate combination of CMV genes may provide a strategy for improving vaccine efficacy.
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Affiliation(s)
- C S Morello
- Department of Pathology, University of California, San Diego, La Jolla, California 92093-0366, USA
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31
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Schleiss MR, McGregor A, Jensen NJ, Erdem G, Aktan L. Molecular characterization of the guinea pig cytomegalovirus UL83 (pp65) protein homolog. Virus Genes 1999; 19:205-21. [PMID: 10595412 DOI: 10.1023/a:1008136714136] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The tegument phosphoproteins of human cytomegalovirus (HCMV) elicit cytotoxic T-lymphocyte (CTL) responses and are hence candidates for subunit vaccine development. Little is known, however, about the tegument proteins of nonhuman cytomegaloviruses, such as guinea pig CMV (GPCMV). DNA sequence analysis of the Eco R I "C" fragment of the GPCMV genome identified an open reading frame (ORF) which is colinear with that of the HCMV tegument phosphoprotein, UL83 (pp65). This ORF was found to have identity to HCMV UL83 and was predicted to encode a 565-amino-acid (aa) protein with a molecular mass of 62.3 kDa. Transcriptional analyses revealed that a GPCMV UL83 probe hybridized with both 2.2 kb and 4.2 kb mRNA species at 48 h post-infection (p.i.); synthesis of these messages was blocked by phosphonoacetic acid (PAA), defining these as "late" gene transcripts. In vitro translation of the UL83 ORF in reticulocyte lysate resulted in synthesis of a 65 kDa protein. Immunofluorescence experiments revealed that the putative GPCMV UL83 homolog exhibited a predominantly nuclear localization pattern. Polyclonal antisera were raised against a UL83/glutathione-S-transferase (GST) fusion protein. This antibody identified a 70-kDa virion-associated protein, the putative GPCMV UL83 homolog, in immunoblot and radioimmunoprecipitation experiments. Labeling experiments with 32P-orthophosphate indicated that the GPCMV UL83 protein is phosphorylated. Western blot analysis of glycerol tartrate gradient-purified virions and dense bodies confirmed that the putative GPCMV UL83 homolog was a constituent of both fractions.
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Affiliation(s)
- M R Schleiss
- Division of Infectious Diseases, Children's Hospital Research Foundation, Cincinnati, Ohio 45229, USA
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32
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Beuken E, Grauls G, Bruggeman CA, Vink C. The rat cytomegalovirus R32 gene encodes a virion-associated protein that elicits a strong humoral immune response in infected rats. J Gen Virol 1999; 80 ( Pt 10):2719-2728. [PMID: 10573166 DOI: 10.1099/0022-1317-80-10-2719] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A gene of rat cytomegalovirus (RCMV), designated R32, has been identified that encodes a homologue of the human cytomegalovirus (HCMV) pp150 (ppUL32) major tegument phosphoprotein. The R32 ORF has the capacity to encode a 667 amino acid polypeptide (pR32) with a calculated molecular mass of 73 kDa. The predicted amino acid sequence of pR32 shows similarity to that of polypeptides predicted to be encoded by the HCMV UL32, murine cytomegalovirus M32 and human herpesvirus types 6 and 7 U11 genes. The R32 gene is transcribed as a 2.5 kb mRNA during the late phase of RCMV infection in rat embryo fibroblasts in vitro. To study expression of the pR32 protein in vitro and in vivo, a rabbit polyclonal antiserum was raised against a recombinant protein that comprised amino acids 252-522 of pR32. By using this antiserum, pR32 could be detected predominantly in the cytoplasm of RCMV-infected fibroblasts at 24 and 48 h post-infection in vitro. The pR32 protein was also detected within virions isolated from the culture medium of RCMV-infected cells. Expression of pR32 in vivo was observed within the cytoplasm of salivary gland epithelial cells of RCMV-infected rats. In addition, recombinant pR32 was found to react with sera from rats that were previously infected with RCMV, whereas reactivity was not seen with sera from mock-infected rats. Together, these findings indicate that RCMV pR32 represents the homologue of HCMV ppUL32, both in primary structure and in function.
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Affiliation(s)
- Erik Beuken
- Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 5800, 6202 AZ Maastricht, The Netherlands1
| | - Gert Grauls
- Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 5800, 6202 AZ Maastricht, The Netherlands1
| | - Cathrien A Bruggeman
- Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 5800, 6202 AZ Maastricht, The Netherlands1
| | - Cornelis Vink
- Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 5800, 6202 AZ Maastricht, The Netherlands1
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33
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Wu CA, Carlson ME, Henry SC, Shanley JD. The murine cytomegalovirus M25 open reading frame encodes a component of the tegument. Virology 1999; 262:265-76. [PMID: 10502507 DOI: 10.1006/viro.1999.9942] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The murine cytomegalovirus (MCMV) monoclonal antibody 5C7:6 was used in Western analysis to probe MCMV infected murine embryo cells (MEC). This antibody recognizes three virus specific polypeptides of 130, 105, and 95 kDa and pulse-chase experiments demonstrated that these three proteins, although antigenically related, are distinct. The 105- and 95-kDa species were expressed with early kinetics, whereas the 130-kDa protein was synthesized as a true late. By screening a lambdagt11 MCMV cDNA library, the gene encoding these proteins was identified as the M25 open reading frame previously reported by Dallas et al. (Dallas, P. B., Lyons, P. A., Hudson, J. B., Scalzo, A. A., and Shellam, G. R., 1994, Virology 200, 643-650). Immunofluorescent studies monitored the location of pM25, present in the nucleus at 15 h after infection, condensing around the periphery of the nucleus at 18 h, before finally accumulating in the cytoplasm. Immunoelectron microscopy detected gold particles associated with the viral tegument of enveloped virions located in the cytoplasm and extracellular space but not with naked nucleocapsids. Western analysis of MCMV purified virions depicted the presence of the 130-kDa protein, the predominant M25 species, in mature virus particles. Together these findings provide compelling evidence that the 130-kDa M25 polypeptide is a component of the viral tegument.
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MESH Headings
- Animals
- Antibodies, Monoclonal
- Cell Nucleus/metabolism
- Cell Nucleus/ultrastructure
- Cell Nucleus/virology
- Cells, Cultured
- Cloning, Molecular
- Cytoplasm/metabolism
- Cytoplasm/ultrastructure
- Cytoplasm/virology
- DNA, Complementary/genetics
- Embryo, Mammalian/cytology
- Embryo, Mammalian/metabolism
- Embryo, Mammalian/virology
- Female
- Gene Expression Regulation, Viral
- Genes, Viral/genetics
- Mice
- Mice, Inbred Strains
- Microscopy, Immunoelectron
- Molecular Weight
- Muromegalovirus/chemistry
- Muromegalovirus/genetics
- Muromegalovirus/isolation & purification
- Muromegalovirus/ultrastructure
- Nucleocapsid/metabolism
- Open Reading Frames/genetics
- Peptides/chemistry
- Peptides/genetics
- Peptides/metabolism
- Viral Envelope Proteins/chemistry
- Viral Envelope Proteins/genetics
- Viral Envelope Proteins/metabolism
- Virus Assembly
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Affiliation(s)
- C A Wu
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, 06030-3212, USA.
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34
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Morello CS, Cranmer LD, Spector DH. In vivo replication, latency, and immunogenicity of murine cytomegalovirus mutants with deletions in the M83 and M84 genes, the putative homologs of human cytomegalovirus pp65 (UL83). J Virol 1999; 73:7678-93. [PMID: 10438858 PMCID: PMC104295 DOI: 10.1128/jvi.73.9.7678-7693.1999] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously identified two open reading frames (ORFs) of murine cytomegalovirus (MCMV), M83 and M84, which are putative homologs of the human cytomegalovirus (HCMV) UL83 tegument phosphoprotein pp65 (L. D. Cranmer, C. L. Clark, C. S. Morello, H. E. Farrell, W. D. Rawlinson, and D. H. Spector, J. Virol. 70:7929-7939, 1996). In this report, we show that unlike the M83 gene product, the M84 protein is expressed at early times in the infection and cannot be detected in the virion. To elucidate the functional differences between the two pp65 homologs in acute and latent MCMV infections, we constructed two MCMV K181 mutants in which either the M83 or M84 ORF was deleted. The resultant viruses, designated DeltaM83 and DeltaM84, respectively, were found to replicate in NIH 3T3 cells with kinetics identical to those of the parent strain. Western blot analysis demonstrated that except for the absence of M83 or M84 protein expression in the respective mutants, no global perturbations of protein expression were detected. When DeltaM83 and DeltaM84 were inoculated intraperitoneally (i.p.) into BALB/c mice, both viruses showed similar attenuated growth in the spleen, liver, and kidney. However, only DeltaM83 was severely growth restricted in the salivary glands, a phenotype that was abolished upon restoration of the M83 ORF. DeltaM83's growth was similarly restricted in the salivary glands of the resistant C3H/HeN or highly sensitive 129/J strain, as well as in the lungs of all three strains following intranasal inoculation. Using a nested-PCR assay, we found that both DeltaM83 and DeltaM84 established latency in BALB/c mice, with slightly decreased levels of DeltaM83 and DeltaM84 genomic DNAs, relative to K181, observed in the salivary glands and lungs. Immunization of BALB/c mice with 10(5) PFU of K181, DeltaM83, or DeltaM84 i.p. provided similar levels of protection against lethal challenge. Although immunization with 200 PFU of DeltaM83 also provided complete protection, this dose allowed both the immunizing and challenge viruses to establish latency in the spleen. Our results show that the two MCMV pp65 homologs differ in their expression kinetics, virion association, and influence on viral tropism and/or dissemination.
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Affiliation(s)
- C S Morello
- Department of Pathology, University of California, San Diego, La Jolla, California 92093-0366, USA
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35
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Hanson LK, Dalton BL, Karabekian Z, Farrell HE, Rawlinson WD, Stenberg RM, Campbell AE. Transcriptional analysis of the murine cytomegalovirus HindIII-I region: identification of a novel immediate-early gene region. Virology 1999; 260:156-64. [PMID: 10405367 DOI: 10.1006/viro.1999.9796] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cytomegaloviruses likely encode numerous gene products involved in regulating virus-host cell interactions and pathogenesis. We previously identified a region of murine cytomegalovirus (MCMV) within HindIII-J and -I that regulates pathogenesis of the virus [open reading frames (ORFs) M139-M141] or is likely required for MCMV replication (ORFs m142 and m143). As a prerequisite for further studies on the structure and function of this gene region, we mapped the transcripts encoded within MCMV HindIII-I. Probes for ORFs M140 and M141 hybridized to 5.4- and 7.0-kb RNA, respectively, which were transcribed with early kinetics and were 3' coterminal with HindIII-J ORF M139. Probes representing ORFs m142, m143, or m144 hybridized to 3' coterminal transcripts of 1.8, 3.8, and 5.1 kb, respectively. ORFs m142 and m143 were transcribed with immediate-early kinetics but were most abundantly expressed at early times. Probes for the rightmost end of HindIII-I hybridized to a 5. 1-kb early/late RNA corresponding to m144 and to a 1.8-kb early RNA transcribed from m145. All of the major transcripts were polyadenylated and therefore are likely coding. Additional minor transcripts of intermediate sizes were also detected. ORFs M139-m143 showed homology to the betaherpesvirus-specific HCMV US22 gene family. Because deletion of these viral genes results in attenuated or helper-dependent phenotypes, this conserved region of US22 family genes may have a role in virus replication as well as in the pathogenesis of betaherpesviruses in their natural hosts.
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Affiliation(s)
- L K Hanson
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia, 23507, USA
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36
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Abstract
Human cytomegalovirus is ubiquitous, yet causes little illness in immunocompetent individuals. Disease is evident in immunodeficient groups such as neonates, transplant recipients and AIDS patients either following a primary infection or reactivation of a latent infection. Little is known of the mechanisms underlying the pathogenicity of the virus. The recent determination of the nucleotide sequence of both human cytomegalovirus (strain AD169) and murine cytomegalovirus (murine cytomegalovirus strain Smith) has allowed an analysis of the biological importance of several virus genes. Studies with human cytomegalovirus have indicated that many viral genes are non-essential for replication in vitro which are thus assumed to be important in the pathogenesis of the virus. This is being examined in the murine model where the role of the gene and its product in disease can be directly examined in vivo using viral mutants in which the relevant gene has been interrupted or deleted. Current information on the role of cytomegalovirus genes in tissue tropism, immune evasion, latency, reactivation from latency and damage is described.
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Affiliation(s)
- C Sweet
- School of Biological Sciences, University of Birmingham, UK.
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37
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Gallina A, Simoncini L, Garbelli S, Percivalle E, Pedrali-Noy G, Lee KS, Erikson RL, Plachter B, Gerna G, Milanesi G. Polo-like kinase 1 as a target for human cytomegalovirus pp65 lower matrix protein. J Virol 1999; 73:1468-78. [PMID: 9882353 PMCID: PMC103972 DOI: 10.1128/jvi.73.2.1468-1478.1999] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/1998] [Accepted: 11/13/1998] [Indexed: 11/20/2022] Open
Abstract
Human cytomegalovirus (HCMV) pp65 protein is the major constituent of viral dense bodies but is dispensable for viral growth in vitro. pp65 copurifies with a S/T kinase activity and has been implicated in phosphorylation of HCMV IE1 immediate-early protein and its escape from major histocompatibility complex 1 presentation. Furthermore, the presence of pp65 correlates with a virion-associated kinase activity. To clarify the role of pp65, yeast two-hybrid system (THS) screening was performed to identify pp65 cellular partners. A total of 18 out of 48 yeast clones harboring cDNAs for putative pp65 binding proteins encoded the Polo-like kinase 1 (Plk1) C-terminal domain. Plk1 behaved as a bona fide pp65 partner in THS control crosses, and the interaction was confirmed by in vitro binding experiments. Endogenous Plk1 was coimmunoprecipitated with pp65 from transiently transfected COS7 cells. In infected fibroblasts, Plk1 was coimmunoprecipitated with pp65 at late infection stages. Furthermore, Plk1 was detected within wild-type HCMV particles but not within the particles of a pp65-negative mutant (RVAd65). The hydrophilic region of pp65 was phosphorylated in vitro by Plk1. These results suggest that one function of pp65 may be to capture a cell kinase, perhaps in order to alter its activity, nucleotide preference, substrate specificity, or subcellular localization to the advantage of HCMV.
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Affiliation(s)
- A Gallina
- Istituto di Genetica Biochimica ed Evoluzionistica, Consiglio Nazionale delle Ricerche, Pavia, Italy
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38
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MacDonald MR, Li XY, Stenberg RM, Campbell AE, Virgin HW. Mucosal and parenteral vaccination against acute and latent murine cytomegalovirus (MCMV) infection by using an attenuated MCMV mutant. J Virol 1998; 72:442-51. [PMID: 9420244 PMCID: PMC109393 DOI: 10.1128/jvi.72.1.442-451.1998] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/1997] [Accepted: 08/19/1997] [Indexed: 02/05/2023] Open
Abstract
We used a live attenuated murine cytomegalovirus (MCMV) mutant to analyze mechanisms of vaccination against acute and latent CMV infection. We selected MCMV mutant RV7 as a vaccine candidate since this virus grows well in tissue culture but is profoundly attenuated for growth in normal and severe combined immunodeficient (SCID) mice (V. J. Cavanaugh et al., J. Virol. 70:1365-1374, 1996). BALB/c mice were immunized twice (0 and 14 days) subcutaneously (s.c.) with tissue culture-passaged RV7 and then challenged with salivary gland-passaged wild-type MCMV (sgMCMV) intraperitoneally (i.p.) on day 28. RV7 vaccination protected mice against challenge with 10(5) PFU of sgMCMV, a dose that killed 100% of mock-vaccinated mice. RV7 vaccination reduced MCMV replication 100- to 500-fold in the spleen between 1 and 8 days after challenge. We used the capacity to control replication of MCMV in the spleen 4 days after challenge as a surrogate for protection. Protection was antigen specific and required both live RV7 and antigen-specific lymphocytes. Interestingly, RV7 was effective when administered s.c., i.p., perorally, intranasally, and intragastrically, demonstrating that attenuated CMV applied to mucosal surfaces can elicit protection against parenteral virus challenge. B cells and immunoglobulin G were not essential for RV7-induced immunity since B-cell-deficient mice were effectively vaccinated by RV7. CD8 T cells, but not CD4 T cells, were critical for RV7-induced protection. Depletion of CD8 T cells by passive transfer of monoclonal anti-CD8 (but not anti-CD4) antibody abrogated RV7-mediated protection, and RV7 vaccination was less efficient in CD8 T-cell-deficient mice with a targeted mutation in the beta2-microglobulin gene. Although gamma interferon is important for innate resistance to MCMV, it was not essential for RV7 vaccination since gamma interferon receptor-deficient mice were protected by RV7 vaccination. Establishment of and/or reactivation from latency by sgMCMV was decreased by RV7 vaccination, as measured by diminished reactivation of MCMV from splenic explants. We found no evidence for establishment of splenic latency by RV7 after s.c. vaccination. We conclude that RV7 administered through both systemic and mucosal routes is an effective vaccine against MCMV infection. It may be possible to design human CMV vaccines with similar properties.
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Affiliation(s)
- M R MacDonald
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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