151
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Srinivasan V, Schnitzlein WM, Tripathy DN. Fowlpox virus encodes a novel DNA repair enzyme, CPD-photolyase, that restores infectivity of UV light-damaged virus. J Virol 2001; 75:1681-8. [PMID: 11160666 PMCID: PMC114077 DOI: 10.1128/jvi.75.4.1681-1688.2001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fowlpox virus (FPV), a pathogen of poultry, can persist in desiccated scabs shed from infected hosts. Although the mechanisms which ensure virus survival are unknown, it is likely that some type of remedial action against environmentally induced damage is required. In this regard, we have identified an open reading frame (ORF) coding for a putative class II cyclobutane pyrimidine dimer (CPD)-photolyase in the genome of FPV. This enzyme repairs the UV light-induced formation of CPDs in DNA by using blue light as an energy source and thus could enhance the viability of FPV during its exposure to sunlight. Based on transcriptional analyses, the photolyase gene was found to be expressed late during the FPV replicative cycle. That the resultant protein retained DNA repair activity was demonstrated by the ability of the corresponding FPV ORF to complement functionally a photolyase-deficient Escherichia coli strain. Interestingly, insertional inactivation of the FPV photolyase gene did not impair the replication of such a genetically altered virus in cultured cells. However, greater sensitivity of this mutant than of the parental virus to UV light irradiation was evident when both were subsequently photoreactivated in the absence of host participation. Therefore, FPV appears to incorporate its photolyase into mature virions where the enzyme can promote their survival in the environment. Although expression of a homologous protein has been predicted for some chordopoxviruses, this report is the first to demonstrate that a poxvirus can utilize light to repair damage to its genome.
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Affiliation(s)
- V Srinivasan
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana, Illinois 61802, USA
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152
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Brandt TA, Jacobs BL. Both carboxy- and amino-terminal domains of the vaccinia virus interferon resistance gene, E3L, are required for pathogenesis in a mouse model. J Virol 2001; 75:850-6. [PMID: 11134298 PMCID: PMC113981 DOI: 10.1128/jvi.75.2.850-856.2001] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2000] [Accepted: 10/10/2000] [Indexed: 11/20/2022] Open
Abstract
The vaccinia virus (VV) E3L gene is responsible for providing interferon (IFN) resistance and a broad host range to VV in cell culture. The E3L gene product contains two distinct domains. A conserved carboxy-terminal domain, which is required for the IFN resistance and broad host range of the virus, has been shown to bind double-stranded RNA (dsRNA) and inhibit the antiviral dsRNA-dependent protein kinase, PKR. The amino-terminal domain, while conserved among orthopoxviruses, is dispensable in cell culture. To study the role of E3L in whole-animal infections, WR strain VV recombinants either lacking E3L (VVDeltaE3L) or expressing an amino-terminal (VVE3LDelta83N) or carboxy-terminal (VVE3LDelta26C) truncation of E3L were constructed. Whereas wild-type VV had a 50% lethal dose of approximately 10(4) PFU after intranasal infection, and elicited severe weight loss and morbidity, VVDeltaE3L was apathogenic, leading to no death, weight loss, or morbidity. VVDeltaE3L was also apathogenic after intracranial injection. Although the amino-terminal domain of E3L is dispensable for infection of cells in culture, both the amino- and carboxy-terminal domains of E3L were required for full pathogenesis in intranasal infections. These results demonstrate that the entire E3L gene is required for pathogenesis in the mouse model.
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Affiliation(s)
- T A Brandt
- Department of Microbiology, Graduate Program in Molecular and Cellular Biology, Arizona State University, Tempe, Arizona 85287-2701, USA
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153
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Turner SJ, Silke J, Kenshole B, Ruby J. Characterization of the ectromelia virus serpin, SPI-2. J Gen Virol 2000; 81:2425-2430. [PMID: 10993930 DOI: 10.1099/0022-1317-81-10-2425] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Poxviruses encode multiple proteins that enable them to evade host responses. Among these are serine protease inhibitors (serpins). One of the earliest serpins described, cowpox virus crmA, acts to inhibit inflammation and apoptosis. crmA homologous serpins, known as SPI-2, are conserved in rabbitpox, vaccinia and variola viruses. Here, we describe the characterization of ectromelia virus (EV) SPI-2. EV SPI-2 encodes a protein of approximately 38 kDa showing >94% identity with other poxviral homologues. Conservative changes in amino acid sequence were found within the reactive site loop and the serpin backbone. Like crmA, transient expression of SPI-2 protected cells from tumour necrosis factor-mediated apoptosis and inhibited the activity of caspases-1 and -8 but not caspases-3, -6 or granzyme B. Overall, this study demonstrates that EV SPI-2 is functionally similar to crmA, based on in vitro assays.
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Affiliation(s)
- Stephen J Turner
- Department of Microbiology and Immunology, University of Melbourne, Parkville 3010, Australia1
| | - John Silke
- The Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Melbourne 3050, Australia2
| | - Bronwyn Kenshole
- Department of Microbiology and Immunology, University of Melbourne, Parkville 3010, Australia1
| | - Janet Ruby
- Department of Microbiology and Immunology, University of Melbourne, Parkville 3010, Australia1
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154
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Gieryńska M, Toka FN, Cespedes IS, Schollenberger A, Malicka E, Popis A, Niemiałtowski MG. Homing studies on distribution of ectromelia (mousepox) virus-specific T cells adoptively transferred into syngeneic H-2d mice: paradigm of lymphocyte migration. Viral Immunol 2000; 13:107-23. [PMID: 10733173 DOI: 10.1089/vim.2000.13.107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mousepox (infectious ectromelia) may be used as a model for studies on the cellular immune response and pathogenesis of generalized viral infections. Ectromelia virus (EV) initially replicates in the footpad (f.p.) skin at the site of infection, next in draining lymph nodes, and then in the spleen and liver where the virus may induce extensive necrotic process with inflammatory reaction. We show in this study that after recipient BALB/c mice (H-2d) f.p. infection with EV prior to the adoptive transfer of syngeneic donor EV-specific cytotoxic T lymphocytes interferon-gamma-positive (IFN-gamma-+), interleukin-2-positive (IL-2+), and IL-4+ of both phenotypes, CD8+ approximately 70%, and CD4+ approximately 30%) preferentially migrated to the inguinal and auxiliary lymph nodes, spleen, liver, and skin at the site of infection (f.p.). Many particles of EV with the morphology characteristic for orthopoxviruses and virus-specific immunofluorescence within the cells of inguinal and auxiliary lymph nodes, liver, spleen, and skin have been observed using high-resolution transmission electron microscopy and fluorescence antibody technique, respectively. Results presented in this article support the concept that immune T cells adoptively transferred into infected recipient mice are able not only to specific migration in the host and homing in the sites of virus replication, but also to develop immunoprotection in the transferred animals.
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MESH Headings
- Adoptive Transfer
- Animals
- Antigens, Viral/analysis
- Cytokines/metabolism
- Cytotoxicity Tests, Immunologic
- Ectromelia virus/immunology
- Ectromelia virus/isolation & purification
- Ectromelia, Infectious/immunology
- Ectromelia, Infectious/pathology
- Ectromelia, Infectious/prevention & control
- Ectromelia, Infectious/virology
- Enzyme-Linked Immunosorbent Assay
- H-2 Antigens/immunology
- Lymphocyte Activation
- Mice
- Mice, Inbred BALB C
- Microscopy, Electron
- Receptors, Lymphocyte Homing/metabolism
- T-Lymphocytes/immunology
- T-Lymphocytes/transplantation
- T-Lymphocytes, Cytotoxic/immunology
- Transplantation, Isogeneic
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Affiliation(s)
- M Gieryńska
- Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Warsaw Agricultural University, Grochowska, Poland
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155
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156
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Kotwal GJ. Poxviral mimicry of complement and chemokine system components: what's the end game? IMMUNOLOGY TODAY 2000; 21:242-8. [PMID: 10782056 DOI: 10.1016/s0167-5699(00)01606-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Numerous viral proteins mimic host immunoregulatory proteins, both structurally and functionally. This phenomenon appears to underlie viral evasion of host defense. These viral immunomodulatory proteins block viral neutralization and destruction of infected cells, and are also able to influence their habitat, preserving habitats that favor their growth and that of their progeny. The end game seems to vary widely among viruses.
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Affiliation(s)
- G J Kotwal
- Dept of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
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157
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Villacres MC, Zuo J, Bergmann CC. Maintenance of CD8(+) T-cell memory following infection with recombinant sindbis and vaccinia viruses. Virology 2000; 270:54-64. [PMID: 10772979 DOI: 10.1006/viro.2000.0255] [Citation(s) in RCA: 15] [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
CD8(+) T-cell memory is critical for protection against pathogens poorly controlled by humoral immunity. To characterize two distinct vaccine vectors, the acute and memory CD8(+) T-cell responses to an HIV-1 epitope (p18) expressed by recombinant vaccinia (vp18) and Sindbis (SINp18) viruses were compared. Whereas 9 to 13% of CD8(+) splenocytes were p18 specific during the acute response to vp18, 4% were induced by SINp18 as revealed by class I tetramer staining. Increased T-cell activation by vp18 was confirmed by higher numbers of both p18-specific IFN-gamma-secreting splenocytes and activated CD8(+) and CD4(+) T cells. Although higher frequencies of p18-specific CD8(+) T cells during primary responses correlated with higher frequencies during memory, the overall decline was only two- to threefold during the transition to memory, demonstrating equally efficient maintenance of memory in SINp18- as in vp18-immune mice. Despite modest in vivo activation, SINp18-induced CD4(+) T cells secreted substantial amounts of IFN-gamma and IL-2, potentially contributing to sustained CD8(+) memory. Collectively the data indicate that Sindbis virus recombinants provide effective vaccines for inducing protective memory CD8(+) T cells in the absence of the extensive inflammation and replication associated with vaccinia virus.
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Affiliation(s)
- M C Villacres
- Department of Neurology, University of Southern California Keck School of Medicine, Los Angeles, California 90033, USA
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158
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Kennedy MK, Glaccum M, Brown SN, Butz EA, Viney JL, Embers M, Matsuki N, Charrier K, Sedger L, Willis CR, Brasel K, Morrissey PJ, Stocking K, Schuh JC, Joyce S, Peschon JJ. Reversible defects in natural killer and memory CD8 T cell lineages in interleukin 15-deficient mice. J Exp Med 2000; 191:771-80. [PMID: 10704459 PMCID: PMC2195858 DOI: 10.1084/jem.191.5.771] [Citation(s) in RCA: 1282] [Impact Index Per Article: 53.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
C57BL/6 mice genetically deficient in interleukin 15 (IL-15(-/-) mice) were generated by gene targeting. IL-15(-/-) mice displayed marked reductions in numbers of thymic and peripheral natural killer (NK) T cells, memory phenotype CD8(+) T cells, and distinct subpopulations of intestinal intraepithelial lymphocytes (IELs). The reduction but not absence of these populations in IL-15(-/-) mice likely reflects an important role for IL-15 for expansion and/or survival of these cells. IL-15(-/-) mice lacked NK cells, as assessed by both immunophenotyping and functional criteria, indicating an obligate role for IL-15 in the development and functional maturation of NK cells. Specific defects associated with IL-15 deficiency were reversed by in vivo administration of exogenous IL-15. Despite their immunological defects, IL-15(-/-) mice remained healthy when maintained under specific pathogen-free conditions. However, IL-15(-/-) mice are likely to have compromised host defense responses to various pathogens, as they were unable to mount a protective response to challenge with vaccinia virus. These data reveal critical roles for IL-15 in the development of specific lymphoid lineages. Moreover, the ability to rescue lymphoid defects in IL-15(-/-) mice by IL-15 administration represents a powerful means by which to further elucidate the biological roles of this cytokine.
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Affiliation(s)
- M K Kennedy
- Immunex Corporation, Seattle, Washington 98101, USA
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159
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Kolokotronis A, Antoniades D, Katsoulidis E, Kioses V. Facial and perioral molluscum contagiosum as a manifestation of HIV infection. Aust Dent J 2000; 45:49-52. [PMID: 10846273 DOI: 10.1111/j.1834-7819.2000.tb00242.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molluscum contagiosum (MC) is a self-limiting viral disease of the skin and the mucous membranes. Facial and perioral MC is seen with increasing frequency in human immunodeficiency (HIV) infection, particularly in HIV infected homosexual men. The purpose of this study was to describe clinical observations of facial and perioral MC in HIV infected patients. One hundred and eighty HIV-positive individuals (160 males and 20 females) were examined over a period of five years. Fifty-eight were homosexual men and 19 were bisexual men. Fifty-one of 180 patients at the time of the first examination had CD+4 count < 200 cells/mm3 and another 63 presented loss of CD+4 cells in this level, during this period. Three HIV infected patients (two homosexual and one bisexual) were affected with facial and perioral MC. At the time of MC diagnosis the CD+4 count was less than 200 cells/mm3 for all three patients. One patient died nine months after MC diagnosis and the other two are still alive. It is remarkable that in this study no clinical lesions were observed on other sites of the skin.
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Affiliation(s)
- A Kolokotronis
- Dental School of Aristotle, University of Thessaloniki, Greece
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160
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Martinez MJ, Bray MP, Huggins JW. A mouse model of aerosol-transmitted orthopoxviral disease: morphology of experimental aerosol-transmitted orthopoxviral disease in a cowpox virus-BALB/c mouse system. Arch Pathol Lab Med 2000; 124:362-77. [PMID: 10705388 DOI: 10.5858/2000-124-0362-ammoat] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVES To determine the morphologic changes and disease progression of aerosolized cowpox virus infection in BALB/c mice and to ascertain the suitability of cowpox virus-infected BALB/c mice as a model of aerosol-transmitted, orthopoxviral respiratory disease. METHODS BALB/c mice were inoculated with cowpox virus, Brighton strain, by aerosol or intranasal route. Mice were killed at specified times after inoculation, necropsied, and tissues were collected for routine histology, immunohistochemistry, and electron microscopy. RESULTS Inoculation by both routes resulted in disease and death. Immunolabeled viral antigen and lesions predominated in the tissues associated with the inoculation route, that is, lungs, airways, trachea, and nasal passages and sinuses. Tracheitis was evident in the intranasally infected group only. Lesions were generally necrotizing and hemorrhagic, neutrophilic, and increased in extent and severity in a time-dependent fashion. Viral intracytoplasmic inclusion bodies, immunolabeled viral antigen, or virions were readily seen in epithelial tissues, smooth muscle cells of airways and vessels, fibroblasts, periosteal cells, perineural cells, and macrophages. Although the extension of infection appeared to be primarily direct, lesions suggesting hematogenous dissemination were occasionally noted in bone marrow and skin. Transmission electron microscopy demonstrated features of cell injury or death, virion assembly and maturation, and both A-type and B-type inclusions. CONCLUSIONS Aerosol inoculation of BALB/c mice with cowpox virus provides a reliable and facilitative model of aerosol-transmitted, orthopoxviral respiratory disease.
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Affiliation(s)
- M J Martinez
- Pathology Division, US Army Medical Research Institute of Infectious Diseases, Ft. Detrick, MD 21702-5011, USA
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161
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Chen N, Buller RM, Wall EM, Upton C. Analysis of host response modifier ORFs of ectromelia virus, the causative agent of mousepox. Virus Res 2000; 66:155-73. [PMID: 10725549 DOI: 10.1016/s0168-1702(99)00135-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
From the right-hand end of the ectromelia virus (strain Moscow) genome, 32318 bps have been sequenced, and characterized to include a total of 18 open reading frames (ORFs) and six regions which apparently no longer code for functional proteins. At least six of the ORFs appear to be involved in blocking the inflammatory/immune host response to infection, and therefore probably contribute significantly to the virulence of this virus in its natural host, the mouse. One of these genes encoded an isolog of the poxvirus chemokine binding protein, and was shown to be the most abundant protein secreted from ectromelia virus infected cells. Two regions were found to have significant similarity to poxvirus genes encoding tumor necrosis factor (TNF) binding proteins. Both are distinct from cytokine response modifier (crm)B and crmC but only one is predicted to encode a functional TNF binding protein. A novel similarity between the C-terminal domain of poxvirus TNF binding proteins and several other poxvirus proteins is also presented. The results are discussed in the context of ectromelia virus pathogenesis of mice.
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Affiliation(s)
- N Chen
- Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, 1402 South Grand Boulevard, St. Louis, MO 63104, USA
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162
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Price N, Tscharke DC, Hollinshead M, Smith GL. Vaccinia virus gene B7R encodes an 18-kDa protein that is resident in the endoplasmic reticulum and affects virus virulence. Virology 2000; 267:65-79. [PMID: 10648184 DOI: 10.1006/viro.1999.0116] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This paper presents a characterisation of vaccinia virus (VV) gene B7R that was predicted to encode a polypeptide of 182 amino acids with an N-terminal signal peptide. In vitro transcription and translation analysis showed the B7R gene product was a 21-kDa protein that, in the presence of microsomes, was processed into an 18-kDa mature form. The 18-kDa form associated with the microsomal membranes and was within the lumen of the vesicle where it was inaccessible to exogenous protease or an antibody raised against the B7R C terminus. Within VV-infected cells, the 18-kDa form of B7R was detected late during infection in the endoplasmic reticulum where it colocalised with protein disulphide isomerase. The B7R protein was detected neither in the culture supernatant nor associated with virus particles. A virus deletion mutant lacking the B7R gene and a revertant virus were constructed. Compared to wild-type and revertant viruses, the deletion mutant replicated normally in cell culture and had unaltered virulence in a murine intranasal model of infection. However, the deletion mutant was attenuated in a murine intradermal model where it induced a smaller lesion than the control viruses.
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Affiliation(s)
- N Price
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, United Kingdom
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163
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Ramírez JC, Gherardi MM, Esteban M. Biology of attenuated modified vaccinia virus Ankara recombinant vector in mice: virus fate and activation of B- and T-cell immune responses in comparison with the Western Reserve strain and advantages as a vaccine. J Virol 2000; 74:923-33. [PMID: 10623755 PMCID: PMC111613 DOI: 10.1128/jvi.74.2.923-933.2000] [Citation(s) in RCA: 180] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/1999] [Accepted: 10/07/1999] [Indexed: 02/03/2023] Open
Abstract
The modified vaccinia virus Ankara (MVA) strain is a candidate vector for vaccination against pathogens and tumors, due to safety concerns and the proven ability of recombinants based on this vector to trigger protection against pathogens in animals. In this study we addressed the fate of the MVA vector in BALB/c mice after intraperitoneal inoculation in comparison with that of the replication-competent Western Reserve (WR) strain by measuring levels of expression of the reporter luciferase gene, the capability to infect target tissues from the site of inoculation, and the length of time of virus persistence. We evaluated the extent of humoral and cellular immune responses induced against the virus antigens and a recombinant product (beta-galactosidase). We found that MVA infects the same target tissues as the WR strain; surprisingly, within 6 h postinoculation the levels of expression of antigens were higher in tissues from MVA-infected mice than in tissues from mice infected with wild-type virus but at later times postinoculation were 2 to 4 log units higher in tissues from WR-infected mice. In spite of this, antibodies and cellular immune responses to viral vector antigens were considerably lower in MVA-inoculated mice than in WR virus-inoculated mice. In contrast, the cellular immune response to a foreign antigen expressed from MVA was similar to and even higher than that triggered by the recombinant WR virus. MVA elicited a Th1 type of immune response, and the main proinflammatory cytokines induced were interleukin-6 and tumor necrosis factor alpha. Our findings have defined the biological characteristics of MVA infection in tissues and the immune parameters activated in the course of virus infection. These results are of significance with respect to optimal use of MVA as a vaccine.
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Affiliation(s)
- J C Ramírez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autonoma, 28049 Madrid, Spain
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164
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Moon KB, Turner PC, Moyer RW. SPI-1-dependent host range of rabbitpox virus and complex formation with cathepsin G is associated with serpin motifs. J Virol 1999; 73:8999-9010. [PMID: 10516006 PMCID: PMC112932 DOI: 10.1128/jvi.73.11.8999-9010.1999] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/1999] [Accepted: 07/16/1999] [Indexed: 11/20/2022] Open
Abstract
Serpins are a superfamily of serine proteinase inhibitors which function to regulate a number of key biological processes including fibrinolysis, inflammation, and cell migration. Poxviruses are the only viruses known to encode functional serpins. While some poxvirus serpins regulate inflammation (myxoma virus SERP1 and cowpox virus [CPV] crmA/SPI-2) or apoptosis (myxoma virus SERP2 and CPV crmA/SPI-2), the function of other poxvirus serpins remains unknown. The rabbitpox virus (RPV) SPI-1 protein is 47% identical to crmA and shares all of the serpin structural motifs. However, no serpin-like activity has been demonstrated for SPI-1 to date. Earlier we showed that RPV with the SPI-1 gene deleted, unlike wild-type virus, fails to grow on A549 or PK15 cells (A. Ali, P. C. Turner, M. A. Brooks, and R. W. Moyer, Virology 202:306-314, 1994). Here we demonstrate that in the absence of a functional SPI-1 protein, infected nonpermissive cells which exhibit the morphological features of apoptosis fail to activate terminal caspases or cleave the death substrates PARP or lamin A. We show that SPI-1 forms a stable complex in vitro with cathepsin G, a member of the chymotrypsin family of serine proteinases, consistent with serpin activity. SPI-1 reactive-site loop (RSL) mutations of the critical P1 and P14 residues abolish this activity. Viruses containing the SPI-1 RSL P1 or P14 mutations also fail to grow on A549 or PK15 cells. These results suggest that the full virus host range depends on the serpin activity of SPI-1 and that in restrictive cells SPI-1 inhibits a proteinase with chymotrypsin-like activity and may function to inhibit a caspase-independent pathway of apoptosis.
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Affiliation(s)
- K B Moon
- Department of Molecular Genetics, University of Florida, Gainesville, Florida 32610-0266, USA
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165
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Wherry EJ, Puorro KA, Porgador A, Eisenlohr LC. The Induction of Virus-Specific CTL as a Function of Increasing Epitope Expression: Responses Rise Steadily Until Excessively High Levels of Epitope Are Attained. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.7.3735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
The role of epitope expression levels in CD8+ T cell priming has been controversial. Yet this parameter is of great importance in the design of rational approaches to optimize CTL responses to a variety of pathogens. In this paper we examine the influence of epitope production on CD8+ T cell priming by exploiting a system that allows a 200-fold range of cell surface epitope expression in vitro with a fixed dose of vaccinia virus. Our results demonstrate that, with the exception of a notable decline at the highest level of epitope, the magnitude of the responding CTL population generated in vivo following equivalent viral infections is essentially proportional to epitope density.
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Affiliation(s)
- E. John Wherry
- *Department of Microbiology and Immunology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, PA 19107; and
| | - Kristin A. Puorro
- *Department of Microbiology and Immunology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, PA 19107; and
| | - Angel Porgador
- †Department of Microbiology and Immunology, Faculty Health Sciences, University of Ben-Gurion, Beer-Sheva, Israel
| | - Laurence C. Eisenlohr
- *Department of Microbiology and Immunology, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, PA 19107; and
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166
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Müllbacher A, Wallich R, Moyer RW, Simon MM. Poxvirus-Encoded Serpins Do Not Prevent Cytolytic T Cell-Mediated Recovery from Primary Infections. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.12.7315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
Previous observations that the highly conserved poxvirus-encoded serpins inhibit cytotoxic activities of alloreactive CTL via granule and/or Fas-mediated pathways was taken to indicate their involvement in immune evasion by poxviruses. We now show that interference with 51Cr release from target cells by ectromelia and cowpoxvirus is limited to alloreactive but not MHC-restricted CTL. The data are in support of the paramount importance of CTL and its effector molecule perforin in the recovery from primary ectromelia virus infection and question the role of serpins in the evasion of poxviruses from killing by CTL. Further analysis of poxvirus interference with target cell lysis by alloreactive CTL revealed that suppression primarily affects the Fas-mediated, and to a lesser extent, the granule exocytosis pathway. Serpin-2 is the main contributor to suppression for both killing pathways. In addition, inhibition of lysis was shown to be both target cell type- and MHC allotype-dependent. We hypothesize that differences in TCR affinities and/or state of activation between alloreactive and MHC-restricted CTL as well as the quality (origin) of target cells are responsible for the observed phenomenon.
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Affiliation(s)
- Arno Müllbacher
- *Division of Immunology and Cell Biology, John Curtin School of Medical Research, Australian National University, Canberra, Australia
| | - Reinhard Wallich
- †Institut für Immunologie der Universität Heidelberg, Heidelberg, Germany
| | - Richard W. Moyer
- ‡Department of Immunology and Medical Microbiology, University of Florida, Gainesville, FL; and
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167
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Klapper LN, Glathe S, Vaisman N, Hynes NE, Andrews GC, Sela M, Yarden Y. The ErbB-2/HER2 oncoprotein of human carcinomas may function solely as a shared coreceptor for multiple stroma-derived growth factors. Proc Natl Acad Sci U S A 1999; 96:4995-5000. [PMID: 10220407 PMCID: PMC21805 DOI: 10.1073/pnas.96.9.4995] [Citation(s) in RCA: 308] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The erbB-2/HER2 oncogene is overexpressed in a significant fraction of human carcinomas of the breast, ovary, and lung in a manner that correlates with poor prognosis. Although the encoded protein resembles several receptors for growth factors, no high affinity ligand of ErbB-2 has so far been fully characterized. However, several lines of evidence have raised the possibility that ErbB-2 can augment signal transduction initiated by binding of certain growth factors to their direct receptors. Here, we contrasted these two models of ErbB-2 function: First, examination of a large series of epidermal growth factor (EGF)-like ligands and neuregulins, including virus-encoded ligands as well as related motifs derived from the precursor of EGF, failed to detect interactions with ErbB-2 when this protein was singly expressed. Second, by using antibodies that block inter-ErbB interactions and cells devoid of surface ErbB-2, we learned that signaling by all ligands examined, except those derived from the precursor of EGF, was enhanced by the oncoprotein. These results imply that ErbB-2 evolved as a shared receptor subunit of all ErbB-specific growth factors. Thus, oncogenicity of ErbB-2 in human epithelia may not rely on the existence of a specific ligand but rather on its ability to act as a coreceptor for multiple stroma-derived growth factors.
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Affiliation(s)
- L N Klapper
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
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168
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Nash P, Barrett J, Cao JX, Hota-Mitchell S, Lalani AS, Everett H, Xu XM, Robichaud J, Hnatiuk S, Ainslie C, Seet BT, McFadden G. Immunomodulation by viruses: the myxoma virus story. Immunol Rev 1999; 168:103-20. [PMID: 10399068 DOI: 10.1111/j.1600-065x.1999.tb01286.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Myxoma virus is a poxvirus pathogen of rabbits that has evolved to replicate successfully in the presence of an active immune response by an infected host. To accomplish this, the virus has developed a variety of strategies to avoid detection by or obstruct specific aspects of the antiviral response whose consolidated action is antagonistic to virus survival. We describe two distinct viral strategies carried out by viral proteins with which myxoma virus subverts the host immune response. The first strategy is the production of virus-encoded proteins known as viroceptors or virokines that mimic host receptors or cytokines. These seek to actively block extracellular immune signals required for effective virus clearance and produce a local environment in the infected tissue that is "virus friendly". The second strategy, carried out by intracellular viral proteins, seeks to retard the innate antiviral responses such as apoptosis, and hinder attempts by the infected cell to communicate with the cellular arm of the immune system. By studying these viral strategies of immune evasion, the myxoma system can provide insights into virus-host interactions and also provide new insights into the complex immune system.
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Affiliation(s)
- P Nash
- Department of Microbiology and Immunology, University of Western Ontario, Canada
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169
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Tzahar E, Moyer JD, Waterman H, Barbacci EG, Bao J, Levkowitz G, Shelly M, Strano S, Pinkas-Kramarski R, Pierce JH, Andrews GC, Yarden Y. Pathogenic poxviruses reveal viral strategies to exploit the ErbB signaling network. EMBO J 1998; 17:5948-63. [PMID: 9774339 PMCID: PMC1170922 DOI: 10.1093/emboj/17.20.5948] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Virulence of poxviruses, the causative agents of smallpox, depends on virus-encoded growth factors related to the mammalian epidermal growth factor (EGF). Here we report that the growth factors of Shope fibroma virus, Myxoma virus and vaccinia virus (SFGF, MGF and VGF) display unique patterns of specificity to ErbB receptor tyrosine kinases; whereas SFGF is a broad-specificity ligand, VGF binds primarily to ErbB-1 homodimers, and the exclusive receptor for MGF is a heterodimer comprised of ErbB-2 and ErbB-3. In spite of 10- to 1000-fold lower binding affinity to their respective receptors, the viral ligands are mitogenically equivalent or even more potent than their mammalian counterparts. This remarkable enhancement of cell growth is due to attenuation of receptor degradation and ubiquitination, which leads to sustained signal transduction. Our results imply that signal potentiation and precise targeting to specific receptor combinations contribute to cell transformation at sites of poxvirus infection, and they underscore the importance of the often ignored low-affinity ligand-receptor interactions.
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Affiliation(s)
- E Tzahar
- Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel
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170
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Sandvik T, Tryland M, Hansen H, Mehl R, Moens U, Olsvik O, Traavik T. Naturally occurring orthopoxviruses: potential for recombination with vaccine vectors. J Clin Microbiol 1998; 36:2542-7. [PMID: 9705389 PMCID: PMC105159 DOI: 10.1128/jcm.36.9.2542-2547.1998] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/1997] [Accepted: 06/04/1998] [Indexed: 11/20/2022] Open
Abstract
Orthopoxviruses are being increasingly used as live recombinant vectors for vaccination against numerous infectious diseases in humans, domestic animals, and wildlife. For risk assessments and surveillance, information about the occurrence, distribution and ecology of orthopoxviruses in western Europe is important but has mainly been based on serological investigations. We have examined kidneys, lungs, spleens, and livers of Norwegian small rodents and common shrews (Sorex araneus) for the presence of orthopoxvirus DNA sequences by PCR with primers complementary to the viral thymidine kinase (TK) gene. PCR amplicons were verified as orthopoxvirus specific by hybridization with a vaccinia virus TK-specific probe. A total of 347 animals (1,388 organs) from eight locations in different parts of Norway, collected at different times of the year during 1993 to 1995, were examined. Fifty-two animals (15%) from five locations, up to 1,600 km apart, carried orthopoxvirus DNA in one or more of their organs, most frequently in the lungs. These included 9 of 68 (13%) bank voles (Clethrionomys glareolus), 4 of 13 (31%) gray-sided voles (Clethrionomys rufocanus), 3 of 11 (27%) northern red-backed voles (Clethrionomys rutilus), 16 of 76 (21%) wood mice (Apodemus sylvaticus), and 20 of 157 (13%) common shrews. The previous isolation of cowpox virus from two clinical cases of infection (human and feline) at two of the locations investigated suggests that the viruses detected are cowpox and that some of the virus-carrying small mammalian species should be included among the cowpox virus natural reservoir hosts in Scandinavia and western Europe.
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Affiliation(s)
- T Sandvik
- Department of Arctic Veterinary Medicine, Norwegian College of Veterinary Medicine, N-9005 Tromso, Institute of Medical Biology, University of Tromso, N-9037 Tromso, Norway
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171
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172
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Abstract
Many viruses induce profound changes in cell metabolism and function. Here we show that vaccinia virus induces two distinct forms of cell movement. Virus-induced cell migration was demonstrated by an in vitro wound healing assay in which infected cells migrated independently into the wound area while uninfected cells remained relatively static. Time-lapse microscopy showed that the maximal rate of migration occurred between 9 and 12 h postinfection. Virus-induced cell migration was inhibited by preinactivation of viral particles with trioxsalen and UV light or by the addition of cycloheximide but not by addition of cytosine arabinoside or rifampin. The expression of early viral genes is therefore necessary and sufficient to induce cell migration. Following migration, infected cells developed projections up to 160 microm in length which had growth-cone-like structures and were frequently branched. Time-lapse video microscopy showed that these projections were formed by extension and condensation of lamellipodia from the cell body. Formation of extensions was dependent on late gene expression but not the production of intracellular enveloped (IEV) particles. The requirements for virus-induced cell migration and for the formation of extensions therefore differ from each other and are distinct from the polymerization of actin tails on IEV particles. These data show that poxviruses encode genes which control different aspects of cell motility and thus represent a useful model system to study and dissect cell movement.
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Affiliation(s)
- C M Sanderson
- Sir William Dunn School of Pathology, University of Oxford, United Kingdom
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173
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Wall EM, Cao J, Chen N, Buller RM, Upton C. A novel poxvirus gene and its human homolog are similar to an E. coli lysophospholipase. Virus Res 1997; 52:157-67. [PMID: 9495531 DOI: 10.1016/s0168-1702(97)00122-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A novel poxvirus gene has been characterized within the genome of ectromelia virus. It has significant similarity to a family of lysophospholipases suggesting that it may function in the degradation of lysophospholipids. Since these molecules are active in the stimulation of inflammation, we hypothesize that this gene may play a role in virus virulence. This gene is expressed early in the ectromelia virus replication cycle, before DNA replication. We have also characterized a human cDNA that encodes a protein which is 49.5% identical to the ectromelia virus protein. By its presence in multiple cDNA libraries, this human gene is known to be expressed in a variety of body tissues and is likely to function in the normal regulation of lysophospholipid levels. This family of proteins have conserved blocks of amino acids that are indicative of a serine-aspartic acid-histidine catalytic triad, similar to those used by true lipases and a number of esterases.
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Affiliation(s)
- E M Wall
- Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
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174
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Fleming SB, McCaughan CA, Andrews AE, Nash AD, Mercer AA. A homolog of interleukin-10 is encoded by the poxvirus orf virus. J Virol 1997; 71:4857-61. [PMID: 9151886 PMCID: PMC191714 DOI: 10.1128/jvi.71.6.4857-4861.1997] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A gene encoding a polypeptide with homology to interleukin-10 (IL-10) has been discovered in the genome of orf virus (OV) strain NZ2, a parapoxvirus that infects sheep, goats, and humans. The predicted polypeptide sequence shows high levels of amino acid identity to IL-10 of sheep (80%), cattle (75%), humans (67%), and mice (64%), as well as IL-10-like proteins of Epstein-Barr virus (63%) and equine herpesvirus (67%). The C-terminal region, comprising two-thirds of the OV protein, is identical to ovine IL-10, which suggests that this gene has been captured from its host sheep during the evolution of OV. The IL-10-like gene is transcribed early. Conditioned medium from COS cells transfected with a eukaryotic expression vector containing the OV IL-10-like gene showed the same biological activity as ovine IL-10 in a murine thymocyte proliferation assay. OV IL-10 is likely to be important in immune evasion by OV, since IL-10 is a multifunctional cytokine that has inhibitory effects on nonspecific immunity and Th1 effector function.
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Affiliation(s)
- S B Fleming
- Health Research Council Virus Research Unit and University of Otago Centre for Gene Research, University of Otago, Dunedin, New Zealand.
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175
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Lalani AS, Graham K, Mossman K, Rajarathnam K, Clark-Lewis I, Kelvin D, McFadden G. The purified myxoma virus gamma interferon receptor homolog M-T7 interacts with the heparin-binding domains of chemokines. J Virol 1997; 71:4356-63. [PMID: 9151824 PMCID: PMC191652 DOI: 10.1128/jvi.71.6.4356-4363.1997] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The myxoma virus T7 protein M-T7 is a functional soluble gamma interferon receptor homolog that has previously been shown to bind gamma interferon and inhibit its antiviral activities in a species-specific manner, but gene knockout analysis has suggested a further role for M-T7 in blocking leukocyte influx into infected lesions. We purified M-T7 to apparent homogeneity and showed that M-T7 is an N-linked glycoprotein that appears to be a stable homotrimer with a molecular mass of approximately 113 kDa in solution. M-T7, in addition to forming inhibitory complexes with rabbit gamma interferon, was also shown to bind to human interleukin-8, a prototypic member of the chemokine superfamily. Moreover, M-T7 was able to interact promiscuously with all members of the CXC, CC, and C chemokine subfamilies tested. Binding of human RANTES to M-T7 can be competed by rabbit gamma interferon and also by cold RANTES competitor with a 50% inhibitory concentration of 900 nM. Although M-T7 retains binding to a number of interleukin-8 N-terminal (ELR) deletion mutants, binding to mutants containing deletions in the C-terminal heparin-binding domain of interleukin-8 is abrogated. Furthermore, heparin effectively competes the interaction of M-T7 with the chemokine RANTES but not with rabbit gamma interferon. We propose that this novel M-T7 interaction with members of the chemokine superfamily may be facilitated through the conserved heparin-binding domains found in a wide spectrum of chemokines and that M-T7 may function by modulating chemokine-glycosaminoglycan interactions in virus-infected tissues.
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Affiliation(s)
- A S Lalani
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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176
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Brownstein DG, Gras L. Differential pathogenesis of lethal mousepox in congenic DBA/2 mice implicates natural killer cell receptor NKR-P1 in necrotizing hepatitis and the fifth component of complement in recruitment of circulating leukocytes to spleen. THE AMERICAN JOURNAL OF PATHOLOGY 1997; 150:1407-20. [PMID: 9094996 PMCID: PMC1858154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Innate resistance of C57BL/6 (B6) mice to lethal mousepox is controlled by multiple genes. Previously, four resistance genes were localized to specific subchromosomal regions and transferred onto a susceptible DBA/2 (D2) background by serial backcrossing and intercrossing to produce congenic strains. Intraperitoneally inoculated ectromelia virus was uniformly lethal and achieved similar titers in B6 and D2 mice but elicited differential responses in liver, spleen, and circulating blood leukocytes. The distribution of these response phenotypes in congenic strains linked control of phenotypes with specific subchromosomal regions. D2.R1 mice, which carried a differential segment of chromosome 6, exhibited a B6 liver response and intermediate spleen and circulating leukocyte responses. D2.R2 and D2.R4 mice, which carried differential segments of chromosomes 2 and 1, respectively, exhibited a D2 liver response, a B6 spleen response, and an intermediate circulating leukocyte response. The localization of control of liver response phenotypes to chromosome 6 implicates cells that express natural killer (NK) cell receptor NKR-P1 alloantigens. The localization of control of spleen and circulating leukocyte responses to chromosomes 1, 2, and 6 implicates NK cells, the fifth component of complement, and a gene near the selectin gene complex in recruitment of circulating leukocytes to spleen.
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MESH Headings
- Animals
- Antigens, Surface/genetics
- Antigens, Surface/toxicity
- Chemotaxis, Leukocyte/genetics
- Chemotaxis, Leukocyte/immunology
- Chromosome Mapping
- Complement C5/genetics
- Complement C5/toxicity
- Crosses, Genetic
- Ectromelia, Infectious/etiology
- Ectromelia, Infectious/genetics
- Ectromelia, Infectious/immunology
- Ectromelia, Infectious/mortality
- Ectromelia, Infectious/pathology
- Female
- Genetic Linkage
- Hepatitis, Animal/etiology
- Hepatitis, Animal/genetics
- Hepatitis, Animal/immunology
- Hepatitis, Animal/pathology
- Immunity, Innate
- Killer Cells, Natural/metabolism
- Killer Cells, Natural/virology
- Lectins, C-Type
- Leukocyte Count
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Microsatellite Repeats
- NK Cell Lectin-Like Receptor Subfamily B
- Necrosis
- Spleen/pathology
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Affiliation(s)
- D G Brownstein
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06520-8016, USA
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177
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Miller CG, Shchelkunov SN, Kotwal GJ. The cowpox virus-encoded homolog of the vaccinia virus complement control protein is an inflammation modulatory protein. Virology 1997; 229:126-33. [PMID: 9123854 DOI: 10.1006/viro.1996.8396] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Vaccinia virus complement control protein (VCP) is encoded by vaccinia virus, with its homolog encoded by other pathogenic poxviruses including variola virus. Since rodents are the primary reservoir hosts of cowpox virus (CPV) and since CPV encodes a highly conserved functional homolog of VCP, termed here the inflammation modulatory protein (IMP), the effects of injection of CPV into the footpads of mice was determined in order to study the precise in vivo effects of IMP. Macroscopic examination of the site of injection with a recombinant virus lacking IMP (CPV-IMP) showed greater tissue damage, with more hemorrhage and induration, than sites injected with the wild-type cowpox virus. In addition, the measurement of the specific swelling response carried out for several weeks revealed significantly greater swelling in mice injected with CPV-IMP. Thus, IMP modulates the complement-activated inflammatory response in vivo. Furthermore, the diminished destruction of host tissue observed in the presence of IMP indicates symbiosis in which the virus ensures the preservation of surrounding host tissue, possibly to support the growth of its progeny.
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Affiliation(s)
- C G Miller
- Department of Microbiology and Immunology, University of Louisville School of Medicine, Kentucky 40292, USA
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178
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Mercer AA, Yirrell DL, Whelan EM, Nettleton PF, Pow I, Gilray JA, Reid HW, Robinson AJ. A novel strategy for determining protective antigens of the parapoxvirus, orf virus. Virology 1997; 229:193-200. [PMID: 9123861 DOI: 10.1006/viro.1996.8433] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We investigated the feasibility of using vaccinia virus (VAC) recombinants containing large multigene fragments of orf virus DNA to identify protective antigens of orf virus (OV). Sixteen OV strain NZ2 DNA fragments with an average size of 11.4 kb were recombined into VAC strain Lister. Each fragment was mapped relative to OV restriction endonuclease maps but was otherwise uncharacterized. Together the recombinants represent 95% of the OV genome in an overlapping manner. Immunofluorescence showed all 16 constructs expressed products recognized by OV antiserum and radioimmune precipitation with the same antiserum allowed the localization of the major antigens of OV to specific recombinants. These data indicated the approximate genomic locations of the genes encoding the OV major antigens and showed that their expression was authentic rather than resulting from read through from VAC sequences adjacent to the site of recombination. Vaccination of OV-naive sheep with the recombinant library provided protection against a subsequent challenge with virulent OV. These data confirm the feasibility of the proposed strategy.
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Affiliation(s)
- A A Mercer
- Virus Research Unit, University of Otago, Dunedin, New Zealand.
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179
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Weiss RS, Lee SS, Prasad BV, Javier RT. Human adenovirus early region 4 open reading frame 1 genes encode growth-transforming proteins that may be distantly related to dUTP pyrophosphatase enzymes. J Virol 1997; 71:1857-70. [PMID: 9032316 PMCID: PMC191256 DOI: 10.1128/jvi.71.3.1857-1870.1997] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
An essential oncogenic determinant of subgroup D human adenovirus type 9 (Ad9), which uniquely elicits estrogen-dependent mammary tumors in rats, is encoded by early region 4 open reading frame 1 (E4 ORF1). Whereas Ad9 E4 ORF1 efficiently induces transformed foci on the established rat embryo fibroblast cell line CREF, the related subgroup A Ad12 and subgroup C Ad5 E4 ORF1s do not (R. T. Javier, J. Virol. 68:3917-3924, 1994). In this study, we found that the lack of transforming activity associated with non-subgroup D adenovirus E4 ORF1s in CREF cells correlated with significantly reduced protein levels compared to Ad9 E4 ORF1 in these cells. In the human cell line TE85, however, the non-subgroup D adenovirus E4 ORF1s produced protein levels higher than those seen in CREF cells as well as transforming activities similar to that of Ad9 E4 ORF1, suggesting that all adenovirus E4 ORF1 polypeptides possess comparable cellular growth-transforming activities. In addition, searches for known proteins related to these novel viral transforming proteins revealed that the E4 ORF1 proteins had weak sequence similarity, over the entire length of the E4 ORF1 polypeptides, with a variety of organismal and viral dUTP pyrophosphatase (dUTPase) enzymes. Even though adenovirus E4 ORF1 proteins lacked conserved protein motifs of dUTPase enzymes or detectable enzymatic activity, E4 ORF1 and dUTPase proteins were predicted to possess strikingly similar secondary structure arrangements. It was also established that an avian adenovirus protein, encoded within a genomic location analogous to that of the human adenovirus E4 ORF1s, was a genuine dUTPase enzyme. Although no functional similarity was found for the E4 ORF1 and dUTPase proteins, we propose that human adenovirus E4 ORF1 genes have evolved from an ancestral adenovirus dUTPase and, from this structural framework, developed novel transforming properties.
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Affiliation(s)
- R S Weiss
- Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030, USA
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180
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Schreiber M, Sedger L, McFadden G. Distinct domains of M-T2, the myxoma virus tumor necrosis factor (TNF) receptor homolog, mediate extracellular TNF binding and intracellular apoptosis inhibition. J Virol 1997; 71:2171-81. [PMID: 9032351 PMCID: PMC191324 DOI: 10.1128/jvi.71.3.2171-2181.1997] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The myxoma virus tumor necrosis factor (TNF) receptor homolog, M-T2, is expressed both as a secreted glycoprotein that inhibits the cytolytic activity of rabbit TNF-alpha and as an endoglycosidase H-sensitive intracellular species that prevents myxoma virus-infected CD4+ T lymphocytes from undergoing apoptosis. To compare the domains of M-T2 mediating extracellular TNF inhibition and intracellular apoptosis inhibition, recombinant myxoma viruses expressing nested C-terminal truncations of M-T2 protein were constructed. One mutant, deltaL113, containing intact copies of only two cysteine-rich domains, was not secreted and was incapable of binding rabbit TNF-alpha yet retained full ability to inhibit virus-induced apoptosis of RL-5 cells. Thus, the minimal domain of intracellular M-T2 protein required to inhibit apoptosis is distinct from that required by the extracellular M-T2 for functional TNF-alpha binding and inhibition. This is the first report of a virus-encoded immunomodular protein with two distinct antiimmune properties.
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Affiliation(s)
- M Schreiber
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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181
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Lucas A, Liu L, Macen J, Nash P, Dai E, Stewart M, Graham K, Etches W, Boshkov L, Nation PN, Humen D, Hobman ML, McFadden G. Virus-encoded serine proteinase inhibitor SERP-1 inhibits atherosclerotic plaque development after balloon angioplasty. Circulation 1996; 94:2890-900. [PMID: 8941118 DOI: 10.1161/01.cir.94.11.2890] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Recurrent atherosclerotic plaque growth, restenosis, is a significant clinical problem after interventional procedures. Initiation of restenosis involves activation of inflammatory and thrombotic cascades, which are regulated by serine proteinase enzymes and inhibitors. We have investigated the use of a viral serine proteinase inhibitor, SERP-1, to reduce plaque development after primary balloon angioplasty. This is the first experimental report of the use of a viral anti-inflammatory protein for the prevention of atherosclerosis. METHODS AND RESULTS Seventy-four cholesterol-fed rabbits were treated with either local or systemic infusions of SERP-1 protein (or control solutions) after balloon-mediated injury. Sites of SERP-1 infusion in rabbits had dramatically reduced plaque compared with control infusions at the 4-week follow-up. At low-dose infusions (30 to 300 pg), only the primary infusion site had a demonstrable decrease in plaque, whereas at higher-dose infusions (> 3000 pg), a generalized reduction in plaque development was detected. An associated decrease in mononuclear cell infiltration of the arterial wall was detected after SERP-1 infusion within the first 24 hours. Infusion of an active-site mutant of SERP-1 (P1-P1', ala-ala) lacking serine proteinase inhibitory activity failed to prevent plaque growth. CONCLUSIONS Purified SERP-1, a virus-encoded secreted glycoprotein, reduces plaque growth after primary balloon-mediated injury. Plaque development is decreased by inhibition of serine proteinase activity and is associated with a focal reduction in macrophage infiltration immediately after injury. Investigation of serine proteinase inhibitors may provide new insight into the regulation of arterial responses to injury.
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Affiliation(s)
- A Lucas
- Department of Medicine, University of Alberta, Edmonton, Canada.
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182
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Karupiah G, Buller RM, Van Rooijen N, Duarte CJ, Chen J. Different roles for CD4+ and CD8+ T lymphocytes and macrophage subsets in the control of a generalized virus infection. J Virol 1996; 70:8301-9. [PMID: 8970949 PMCID: PMC190917 DOI: 10.1128/jvi.70.12.8301-8309.1996] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The importance of T-lymphocyte subsets in the control of poxvirus infections is controversial. To determine the relative contribution of lymphocyte subsets important for recovery from infection with ectromelia virus (EV), a natural murine poxvirus pathogen, C57BL/6 (B6) mice lacking functional CD8+ T cells because of disruption of the beta2-microglobulin gene or lacking functional CD4+ T cells because of disruption of the I-(A)beta gene, acutely depleted of CD8+ or CD4+ T cells with monoclonal antibody, or depleted of macrophage subsets by the macrophage suicide technique were used. Recovery from infection was strictly dependent on the effector functions of CD8+ T cells, in the absence of which 100% mortality resulted. This lymphocyte population had demonstrable antiviral activity early in the infection process even before class I major histocompatibility complex (MHC)-restricted CD8+ cytotoxic T-lymphocyte (CTL) activity was detectable. CD4+ T cells were found to be necessary for the generation of an optimal virus-specific, class I MHC-restricted CD8+ CTL response and contributed to virus clearance not involving cytolytic mechanisms. In both models of CD4+ T-cell deficiency, virus clearance was incomplete and persisted at low levels in most organs and at very high levels in the skin, but the animals did not die. The elimination of macrophage subpopulations impeded virus clearance, impaired the generation of class I MHC-restricted antiviral CTL response, and resulted in 100% mortality. These findings establish an absolute requirement for CD8+ and CD4+ T lymphocytes and macrophage subsets in the elimination of a natural murine poxvirus infection and support the idea that macrophages may be essential accessory cells for the generation of class I MHC-restricted antiviral CTL responses.
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Affiliation(s)
- G Karupiah
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892, USA.
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183
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Abstract
Poxviruses encode a broad range of proteins that counteract the formidable attack of the immune response initiated in the host after infection, among which are proteins that mimic the extracellular binding domain of host cytokine receptors and are secreted from virus-infected cells. A soluble interferon-gamma receptor (IFN-gamma R) is produced early after infection and efficiently blocks the binding of IFN-gamma to cellular receptors, thus inhibiting both the anti-viral and immune functions of IFN-gamma. An IFN-gamma R is highly conserved among members of the poxvirus family, suggesting a major role in viral pathogenesis. The highly species-specific nature of the IFN system enables questions concerning the evolutionary relationship between poxviruses and their hosts to be addressed. The IFN-gamma R encoded by myxoma virus, a natural pathogen of rabbits, is specific for rabbit IFN-gamma. However, the IFN-gamma R encoded by orthopoxviruses (vaccinia, cowpox, camelpox, ectromelia) shows a novel, broad species specificity suggesting that these viruses have evolved in several species. The implications for the unknown origin and natural host(s) of vaccinia virus are discussed.
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Affiliation(s)
- A Alcamí
- Sir William Dunn School of Pathology, University of Oxford, U.K
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184
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Abstract
Vaccinia virus contains a gene, termed SPI-2 or B13R, that is closely related in its sequence to a potent inhibitor of apoptosis from cowpox virus (crmA). Infection by vaccinia virus protects HeLa cells against apoptosis that is induced by an immunoglobulin M antibody against the fas receptor or by tumor necrosis factor alpha. This effect is profoundly reduced when the SPI-2 gene is deleted. The SPI-2 gene, when transiently expressed in these cells, can also protect against apoptosis mediated by these agents. Given the similarity to crmA, it seems likely that SPI-2 functions in an analogous fashion, inhibiting the activity of ICE protease family members and blocking the onset of apoptosis.
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Affiliation(s)
- M Dobbelstein
- Howard Hughes Medical Institute, Department of Molecular Biology, Princeton University, New Jersey 08544-1014, USA.
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185
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Alcamí A, Smith GL. Receptors for gamma-interferon encoded by poxviruses: implications for the unknown origin of vaccinia virus. Trends Microbiol 1996; 4:321-6. [PMID: 8856871 DOI: 10.1016/0966-842x(96)10051-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Poxviruses encode soluble interferon-gamma receptors (IFN-gamma Rs) that inhibit IFN-gamma activity and play a major role in virus pathogenesis. In contrast to the highly species specific cellular homologues, the vaccinia IFN-gamma R has novel broad species specificity. This has implications for the unknown origin and natural host(s) of vaccinia virus, the vaccine used for smallpox eradication.
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Affiliation(s)
- A Alcamí
- Sir William Dunn School of Pathology, University of Oxford, UK.
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186
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Mossman K, Lee SF, Barry M, Boshkov L, McFadden G. Disruption of M-T5, a novel myxoma virus gene member of poxvirus host range superfamily, results in dramatic attenuation of myxomatosis in infected European rabbits. J Virol 1996; 70:4394-410. [PMID: 8676463 PMCID: PMC190373 DOI: 10.1128/jvi.70.7.4394-4410.1996] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Myxoma virus is a pathogenic poxvirus that induces a lethal myxomatosis disease profile in European rabbits, which is characterized by fulminating lesions at the primary site of inoculation, rapid dissemination to secondary internal organs and peripheral external sites, and supervening gram-negative bacterial infection. Here we describe the role of a novel myxoma virus protein encoded by the M-T5 open reading frame during pathogenesis. The myxoma virus M-T5 protein possesses no significant sequence homology to nonviral proteins but is a member of a larger poxviral superfamily designated host range proteins. An M-T5- mutant virus was constructed by disruption of both copies of the M-T5 gene followed by insertion of the selectable marker p7.5Ecogpt. Although the M-T5- deletion mutant replicated with wild-type kinetics in rabbit fibroblasts, infection of a rabbit CD4+ T-cell line (RL5) with the myxoma virus M-T5- mutant virus resulted in the rapid and complete cessation of both host and viral protein synthesis, accompanied by the manifestation of all the classical features of programmed cell death. Infection of primary rabbit peripheral mononuclear cells with the myxoma virus M-T5-mutant virus resulted in the apoptotic death of nonadherent lymphocytes but not adherent monocytes. Within the European rabbit, disruption of the M-T5 open reading frame caused a dramatic attenuation of the rapidly lethal myxomatosis infection, and none of the infected rabbits displayed any of the characteristic features of myxomatosis. The two most significant histological observations in rabbits infected with the M-T5-mutant virus were (i) the lack of progression of the infection past the primary site of inoculation, coupled with the establishment of a rapid and effective inflammatory reaction, and (ii) the inability of the virus to initiate a cellular reaction within secondary immune organs. We conclude that M-T5 functions as a critical virulence factor by allowing productive infection of immune cells such as peripheral lymphocytes, thus facilitating virus dissemination to secondary tissue sites via the lymphatic channels.
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Affiliation(s)
- K Mossman
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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187
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Abstract
Vaccinia virus has recently been shown to induce inside its host cells the formation of actin tails very similar to those which facilitate the cell-to-cell spread of several pathogenic bacteria.
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Affiliation(s)
- E J Strauss
- Department of Microbiology and Immunology, Fairchild Science Building, Stanford University School of Medicine, Stanford, California 94305-5402, USA
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188
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Abstract
The incidence of certain microbial infections occurring in the oropharynx is well documented, but infection by other pathogens, although highly probable, has not been established with certainty. Considerable recent interest in the incubation period of various infections and improved community surveillance programs combine to ascribe infection to specific incidents. It is prudent for health care personnel to acknowledge the presence of many sexually transmitted diseases in the oropharynx and consider them in the differential diagnosis of many well-established conditions.
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Affiliation(s)
- G T Terezhalmy
- Department of Dentistry, Cleveland Clinic Foundation, Ohio, USA
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189
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Demkowicz WE, Littaua RA, Wang J, Ennis FA. Human cytotoxic T-cell memory: long-lived responses to vaccinia virus. J Virol 1996; 70:2627-31. [PMID: 8642697 PMCID: PMC190113 DOI: 10.1128/jvi.70.4.2627-2631.1996] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Peripheral T lymphocytes can be classified into two groups: naive and memory T cells. The focus of this study was to examine the duration of T-cell memory in humans. Vaccinia virus replicates in the cytoplasm of infected cells and is not thought to persist or become latent after the acute phase of infection. We identified long-lived vaccinia virus-specific memory cytotoxic T cells in adults who had been immunized against smallpox as children. Initially, we detected vaccinia virus-specific T cells in peripheral blood mononuclear cells while screening for human immunodeficiency virus type 1 (HIV-1)-specific T-cell responses in HIV-1-seropositive subjects. These individuals had not had contact with vaccinia virus since their primary immunization in early childhood. Several vaccinia virus-specific CD4+ T-cell clones were derived from these donors and characterized. Healthy, HIV-1-seronegative donors who had been immunized against smallpox many (35 to 50) years earlier were also screened for vaccinia virus-specific T-cell immunity. We found significant CD8+ and CD4+ cytotoxic T-cell responses to vaccinia virus after in vitro stimulation, indicating that these memory cells are maintained in vivo for many years. The peripheral blood mononuclear cells of young adults with no history of immunization against smallpox did not develop vaccinia virus-specific T-cell responses after in vitro stimulation. Precursor frequency analysis of the vaccinia virus-specific memory CD4+ T cells from a donor immunized with vaccinia virus 35 years earlier revealed a frequency of 1 in 65,920 CD4+ T cells. We concluded that specific vaccinia virus T-cell immunity can persist for up to 50 years after immunization against smallpox in childhood in the presumed absence of exposure to vaccinia virus.
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Affiliation(s)
- W E Demkowicz
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical Center, Worcester 01655, USA
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190
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Thornton AM, Buller RM, DeVico AL, Wang IM, Ozato K. Inhibition of human immunodeficiency virus type 1 and vaccinia virus infection by a dominant negative factor of the interferon regulatory factor family expressed in monocytic cells. Proc Natl Acad Sci U S A 1996; 93:383-7. [PMID: 8552643 PMCID: PMC40242 DOI: 10.1073/pnas.93.1.383] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
ICSBP is a member of the interferon (IFN) regulatory factor (IRF) family that regulates expression of type I interferon (IFN) and IFN-regulated genes. To study the role of the IRF family in viral infection, a cDNA for the DNA-binding domain (DBD) of ICSBP was stably transfected into U937 human monocytic cells. Clones that expressed DBD exhibited a dominant negative phenotype and did not elicit antiviral activity against vesicular stomatitis virus (VSV) infection upon IFN treatment. Most notably, cells expressing DBD were refractory to infection by vaccinia virus (VV) and human immunodeficiency virus type 1 (HIV-1). The inhibition of VV infection was attributed to defective virion assembly, and that of HIV-1 to low CD4 expression and inhibition of viral transcription in DBD clones. HIV-1 and VV were found to have sequences in their regulatory regions similar to the IFN-stimulated response element (ISRE) to which IRF family proteins bind. Accordingly, these viral sequences and a cellular ISRE bound a shared factor(s) expressed in U937 cells. These observations suggest a novel host-virus relationship in which the productive infection of some viruses is regulated by the IRF-dependent transcription pathway through the ISRE.
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Affiliation(s)
- A M Thornton
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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191
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Sonntag KC, Darai G. Strategy for identifying the gene encoding the DNA polymerase of molluscum contagiosum virus type 1. Virus Genes 1996; 13:31-44. [PMID: 8938977 DOI: 10.1007/bf00576976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Molluscum contagiosum virus (MCV) is a member of the family Poxviridae and pathogenic to humans. MCV causes benign epidermal tumors mainly in children and young adults and is a common pathogen in immunecompromised individuals. The viral DNA polymerase is the essential enzyme involved in the replication of the genome of DNA viruses. The identification and characterization of the gene encoding the DNA polymerase of molluscum contagiosum virus type 1 (MCV-1) was carried out by PCR technology and nucleotide sequence analysis. Computer-aided analysis of known amino acid sequences of DNA polymerases from two members of the poxvirus family revealed a high amino acid sequence homology of about 49.7% as detected between the DNA polymerases of vaccinia virus (genus Orthopoxvirus) and fowlpoxvirus (genus Avipoxvirus). Specific oligonucleotide primers were designed and synthesized according to the distinct conserved regions of amino acid sequences of the DNA polymerases in which the codon usage of the MCV-1 genome was considered. Using this technology a 228 bp DNA fragment was amplified and used as hybridization probe for identifying the corresponding gene of the MCV-1 genome. It was found that the PCR product was able to hybridize to the BamHI MCV-1 DNA fragment G (9.2 kbp, 0.284 to 0.332 map units). The nucleotide sequence of this particular region of the MCV-1 genome (7267 bp) between map coordinates 0.284 and 0.315 was determined. The analysis of the DNA sequences revealed the presence of 22 open reading frames (ORFs-1 to -22). ORF-13 (3012 bp; nucleotide positions 6624 to 3612) codes for a putative protein of a predicted size of 115 kDa (1004 aa) which shows 40.1% identity and 35% similarity to the amino acid sequences of the DNA polymerases of vaccinia, variola, and fowlpoxvirus. In addition significant homologies (30% to 55%) were found between the amino acid sequences of the ORFs 3, -5, -9, and -14 and the amino acid sequences of the E6R, E8R, E10R, and a 7.3 kDa protein of vaccinia and variola virus, respectively. Comparative analysis of the genomic positions of the loci of the detected viral genes including the DNA polymerases of MCV-1, vaccinia, and variola virus revealed a similar gene organization and arrangement.
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Affiliation(s)
- K C Sonntag
- Institut für Medizinische Virologie der Universität Heidelberg, Federal Republic of Germany
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192
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McIntosh AA, Smith GL. Vaccinia virus glycoprotein A34R is required for infectivity of extracellular enveloped virus. J Virol 1996; 70:272-81. [PMID: 8523536 PMCID: PMC189814 DOI: 10.1128/jvi.70.1.272-281.1996] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The vaccinia virus strain Western Reserve (WR) A34R gene encodes a C-type lectin-like glycoprotein, gp22-24, that is present in the outer membrane of extracellular enveloped virus (EEV) with type II membrane topology (S.A. Duncan and G.L. Smith, J. Virol. 66:1610-1621, 1992). Here we that a WR A34R deletion mutant (WR delta A34R) released 19- to 24-fold more EEV from infected cells than did WR virus, but the specific infectivity of the released virions was reduced 5- to 6-fold. Rupture of the WR delta A34R EEV outer envelope by freeze-thawing increased virus infectivity by five- to sixfold, because of the release of infectious intracellular mature virus. All other known EEV-specific proteins are incorporated into WR delta A34R EEV, and thus the loss of gp22-24 is solely responsible for the reduction of EEV specific infectivity. The WR delta A34R virus is highly attenuated in vivo compared with WR or a revertant virus in which the A34R gene was reinserted into WR delta A34R. This attenuation is consistent with the known important role of EEV in virus dissemination and virulence. Vaccinia virus strain International Health Department-J (IHD-J) produces large amounts of EEV and forms comets because of an amino acid substitution within the A34R protein (R. Blasco, R. Sisler, and B. Moss, J. Virol. 67:3319-3325, 1993), but despite this, IHD-J EEV has a specific infectivity equivalent to that of WR EEV. Substitution of the IHD-J A34R gene into the WR strain induced comet formation and greater release of EEV, while coexpression of both genes did not; hence, the WR phenotype is dominant. All orthopoxviruses tested express the A34R protein, but most viruses, including variola virus, have the WR rather than the IHD-J A34R genotype. The A34R protein affects plaque formation, EEV release, EEV infectivity, and virus virulence.
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Affiliation(s)
- A A McIntosh
- Sir William Dunn School of Pathology, University of Oxford, United Kingdom
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193
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Martin-Gallardo A, Moratilla M, Funes JM, Agromayor M, Nuñez A, Varas AJ, Collado M, Valencia A, Lopez-Estebaranz JL, Esteban M. Sequence analysis of a Molluscum contagiosum virus DNA region which includes the gene encoding protein kinase 2 and other genes with unique organization. Virus Genes 1996; 13:19-29. [PMID: 8938976 DOI: 10.1007/bf00576975] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The nucleotide sequence of a near left-terminal region from the genome of Molluscum contagiosum virus subtype I (MCVI) was determined. This region was contained within three adjacent BamHI fragments, designated L (2.4 kilobases (kb)), M (1.8 kb), and N (1.6 kb). BamHI cleavage of MCVI DNA produced another 1.6-kb fragment (N'), which had been mapped 30-50 kb from the L,M region. The MCVI restriction fragments were cloned and end-sequenced. The N fragment that maps at the L,M region was identified by the polymerase chain reaction, using primers devised from the sequence of each fragment. The results from this analysis led to establish the relative position of these fragments within the MCVI genome. The analysis of 3.6 kb of DNA sequence revealed the presence of ten open reading frames (ORFs). Comparison of the amino acid sequence of these ORFs to the amino acid sequence of vaccinia virus (VAC) proteins revealed that two complete MCVI ORFs, termed N1L and L1L, showed high degree of homology with VAC F9 and F10 genes, respectively. The F10 gene encodes a 52-kDa serine/threonine protein kinase (protein kinase 2), an essential protein involved in virus morphogenesis. The MCVI homologue (L1L) encoded a putative polypeptide of 443 aa, with a calculated molecular mass of 53 kDa, and 60.5/30.2% sequence identity/similarity to VAC F10. The MCV N1L (213 aa, 24 kDa) showed 42.6/40.6% amino acid sequence identity/similarity to VAC F9, a gene of unknown function encoding a 24-kDa protein with a hydrophobic C-terminal domain, which was conserved in MCVI. The genomic arrangement of MCVI N1L and L1L was equivalent to that of the vaccinia and variola virus homologues. However, the ORFs contained within MCVI fragment M (leftward) showed no homology, neither similarity in genetic organization, to the genes encoded by the corresponding regions of vaccinia and variola viruses.
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Affiliation(s)
- A Martin-Gallardo
- Centro Nacional de Biotecnología, C.S.I.C., Cantoblanco, Madrid, Spain
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194
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Brooks MA, Ali AN, Turner PC, Moyer RW. A rabbitpox virus serpin gene controls host range by inhibiting apoptosis in restrictive cells. J Virol 1995; 69:7688-98. [PMID: 7494278 PMCID: PMC189710 DOI: 10.1128/jvi.69.12.7688-7698.1995] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Poxviruses are unique among viruses in encoding members of the serine proteinase inhibitor (serpin) superfamily. Orthopoxviruses contain three serpins, designated SPI-1, SPI-2, and SPI-3. SPI-1 encodes a 40-kDa protein that is required for the replication of rabbitpox virus (RPV) in PK-15 or A549 cells in culture (A. N. Ali, P. C. Turner, M. A. Brooks, and R. W. Moyer, Virology 202:305-314, 1994). Examination of nonpermissive human A549 cells infected with an RPV mutant disrupted in the SPI-1 gene (RPV delta SPI-1) suggests there are no gross defects in protein or DNA synthesis. The proteolytic processing of late viral structural proteins, a feature of orthopoxvirus infections associated with the maturation of virus particles, also appears relatively normal. However, very few mature virus particles of any kind are produced compared with the level found in infections with wild-type RPV. Morphological examination of RPV delta SPI-1-infected A549 cells, together with an observed fragmentation of cellular DNA, suggests that the host range defect is associated with the onset of apoptosis. Apoptosis is seen only in RPV delta SPI-1 infection of nonpermissive (A549 or PK-15) cells and is absent in all wild-type RPV infections and RPV delta SPI-2 mutant infections examined to date. Although the SPI-1 gene is expressed early, before DNA replication, the triggering apoptotic event occurs late in the infection, as RPV delta SPI-1-infected A549 cells do not undergo apoptosis when infections are carried out in the presence of cytosine arabinoside. While the SPI-2 (crmA) gene, when transfected into cells, has been shown to inhibit apoptosis, our experiments provide the first indication that a poxvirus serpin protein can inhibit apoptosis during a poxvirus infection.
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Affiliation(s)
- M A Brooks
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville 32610-0266, USA
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195
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Brownstein DG, Gras L. Chromosome mapping of Rmp-4, a gonad-dependent gene encoding host resistance to mousepox. J Virol 1995; 69:6958-64. [PMID: 7474114 PMCID: PMC189614 DOI: 10.1128/jvi.69.11.6958-6964.1995] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
DBA/2 (D2) mice are susceptible and C57BL/6 (B6) mice are resistant to lethal mousepox. A congenic resistant strain, D2.B6-Rmp-4r (D2.R4), was developed by serially backcrossing male mice that survived ectromelia virus infection with D2 mice, beginning with (B6 x D2)F1 mice. Male D2.R4 mice were at least 300-fold more resistant to lethal mousepox than male D2 mice. Female D2.R4 mice were 100-fold more resistant than male D2.R4 mice and 500-fold more resistant than female D2 mice. Neonatal gonadectomy prevented development of resistance in D2.R4 mice of both sexes. Differences in resistance between strains and between sexes correlated with restriction of virus replication in spleen and liver, but gender differences were less evident in liver than in spleen. High-resolution interval mapping of the 19 autosomes of D2.R4 mice using dispersed informative microsatellites as marker loci revealed a segment of distal chromosome 1 to be of B6 origin. Haplotypes for a marker locus, D1Mit57, from the differential segment were determined in (D2.R4 x D2)F1 x D2 backcross mice, which were then infected with ectromelia virus. Significantly more heterozygotes than homozygotes survived ectromelia virus infection in both sexes. Whereas nearly all surviving males were heterozygotes, 44% of surviving females were homozygotes. These results indicate that resistance in D2.R4 mice is determined by a gonad-dependent gene on distal chromosome 1, provisionally named Rmp-4, and by an ovary-dependent factor that is not genetically linked to Rmp-4.
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MESH Headings
- Animals
- Animals, Newborn
- Chromosome Mapping
- Crosses, Genetic
- DNA, Satellite/analysis
- DNA, Satellite/genetics
- DNA, Viral/analysis
- Ectromelia, Infectious/genetics
- Ectromelia, Infectious/immunology
- Female
- Genetic Markers
- Genetic Predisposition to Disease
- Genotype
- Immunity, Innate/genetics
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Orchiectomy
- Ovariectomy
- Poxviridae/isolation & purification
- Poxviridae/physiology
- Sex Characteristics
- Species Specificity
- Spleen/virology
- Time Factors
- Virus Replication
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Affiliation(s)
- D G Brownstein
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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196
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Turner PC, Moyer RW. Orthopoxvirus fusion inhibitor glycoprotein SPI-3 (open reading frame K2L) contains motifs characteristic of serine proteinase inhibitors that are not required for control of cell fusion. J Virol 1995; 69:5978-87. [PMID: 7666502 PMCID: PMC189493 DOI: 10.1128/jvi.69.10.5978-5987.1995] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The cowpox virus (CPV) SPI-3 gene (open reading frame K2L in vaccinia virus) is one of three orthopoxvirus genes whose products are members of the serpin (serine proteinase inhibitor) superfamily. The CPV SPI-3 gene, when overexpressed by using the vaccinia virus/T7 expression system, synthesized two proteins of 50 and 48 kDa. Treatment with the N glycosylation inhibitor tunicamycin converted the two SPI-3 proteins to a single 40-kDa protein, close to the size of 42 kDa predicted from the DNA sequence, suggesting that the SPI-3 protein, unlike the other two orthopoxvirus serpins, is a glycoprotein. Immunoblotting with an anti-SPI-3 antibody showed that the SPI-3 protein is synthesized early in infection prior to DNA replication. SPI-3 inhibits cell-cell fusion during infections with both CPV and vaccinia virus. A transfection assay was devised to test engineered mutants of SPI-3 for the ability to inhibit fusion. Two mutants with C-terminal deletions of 156 and 70 amino acids were completely inactive in fusion inhibition. Site-directed mutations were constructed near the C terminus of SPI-3, in or near the predicted reactive-site loop which is conserved in inhibitory serpins. Substitutions within the loop at the P1 to P1' positions and P5 to P5' positions, inclusive, did not result in any loss of activity, nor did changes at the P17 to P10 residues in the stalk of the reactive loop. Therefore, SPI-3 does not appear to control cell fusion by acting as a serine proteinase inhibitor.
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Affiliation(s)
- P C Turner
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville 32610-0266, USA
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197
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Alcamí A, Smith GL. Cytokine receptors encoded by poxviruses: a lesson in cytokine biology. IMMUNOLOGY TODAY 1995; 16:474-8. [PMID: 7576050 DOI: 10.1016/0167-5699(95)80030-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Poxviruses encode soluble versions of cytokine receptors, which are secreted from the infected cell to block the activity of the cognate cytokine. These viruses offer a unique model system to study the contribution of cytokines to the host response against infection. As discussed here by Antonio Alcamí and Geoffrey Smith, characterization of poxvirus proteins that counteract the immune response may lead to the identification of novel cytokines or cytokine receptors, as well as novel strategies to modulate the inflammatory response.
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Affiliation(s)
- A Alcamí
- Sir William Dunn School of Pathology, University of Oxford, UK
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198
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Barry M, Lee SF, Boshkov L, McFadden G. Myxoma virus induces extensive CD4 downregulation and dissociation of p56lck in infected rabbit CD4+ T lymphocytes. J Virol 1995; 69:5243-51. [PMID: 7636966 PMCID: PMC189357 DOI: 10.1128/jvi.69.9.5243-5251.1995] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Myxoma virus is a pathogenic poxvirus that induces extensive dysregulation of cellular immunity in infected European rabbits. Infection of a rabbit CD4+ T-cell line (RL-5) with myxoma virus results in dramatic reductions of cell surface levels of CD4 as monitored by flow cytometry. The virus-induced downregulation of CD4 requires early but not late viral gene expression and could not be inhibited by staurosporine, an inhibitor of protein kinase C, which effectively blocks phorbol 12-myristate-13-acetate-induced downregulation of CD4. The decrease in total cellular levels of CD4 during myxoma virus infection could be inhibited by the lysosomotrophic agent NH4Cl, suggesting a lysosomal fate for CD4 during myxoma virus infection. Steady-state levels of the CD4-associated protein tyrosine kinase p56lck remained unchanged during myxoma virus infection, suggesting that p56lck dissociates from CD4 prior to CD4 degradation in virus infected cells. Total p56lck kinase activity was unaffected during myxoma virus infection, although the amount of p56lck physically associated with CD4 declined in parallel with the loss of CD4. Thus, myxoma virus infection of CD4+ T lymphocytes triggers CD4 downregulation via a protein kinase C-independent pathway, causing the dissociation of p56lck and the degradation of CD4 in lysosomal vesicles.
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Affiliation(s)
- M Barry
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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199
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Alcamí A, Smith GL. Vaccinia, cowpox, and camelpox viruses encode soluble gamma interferon receptors with novel broad species specificity. J Virol 1995; 69:4633-9. [PMID: 7609027 PMCID: PMC189264 DOI: 10.1128/jvi.69.8.4633-4639.1995] [Citation(s) in RCA: 236] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Soluble receptors for gamma interferon (IFN-gamma) are secreted from cells infected by 17 orthopoxviruses, including vaccinia, cowpox, rabbitpox, buffalopox, elephantpox, and camelpox viruses, representing three species (vaccinia, cowpox, and campelpox viruses). The B8R open reading frame of vaccinia virus strain Western Reserve, which has sequence similarity to the extracellular binding domain of cellular IFN-gamma receptors (IFN-gamma Rs), is shown to encode an IFN-gamma binding activity by expression in recombinant baculovirus. The soluble virus IFN-gamma Rs bind IFN-gamma and, by preventing its interaction with the cellular receptor, interfere with the antiviral effects induced by this cytokine. Interestingly, in contrast to cellular IFN-gamma Rs, which are highly species specific, the vaccinia, cowpox, and camelpox virus IFN-gamma Rs bind and inhibit the biological activity of human, bovine, and rat IFN-gamma but not mouse IFN-gamma. This unique broad species specificity of the IFN-gamma R would aid virus replication in different species and suggests that vaccinia, cowpox, and camelpox viruses may have evolved in several species, possibly including humans but excluding mice. Last, the conservation of an IFN-gamma R in orthopoxviruses emphasizes the importance of IFN-gamma in defense against poxvirus infections.
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Affiliation(s)
- A Alcamí
- Sir William Dunn School of Pathology, University of Oxford, United Kingdom
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Colamonici OR, Domanski P, Sweitzer SM, Larner A, Buller RM. Vaccinia virus B18R gene encodes a type I interferon-binding protein that blocks interferon alpha transmembrane signaling. J Biol Chem 1995; 270:15974-8. [PMID: 7608155 DOI: 10.1074/jbc.270.27.15974] [Citation(s) in RCA: 265] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Poxviruses encode a large number of proteins that attenuate the inflammatory and immune responses to infection. In this report we demonstrate that a number of orthopoxviruses express a type I interferon (IFN)-binding protein, which is encoded by the B18R open reading frame in the WR strain of vaccinia virus. The B18R protein has significant regions of homology with the alpha subunits of the mouse, human, and bovine type I IFN receptors, bound human IFN alpha 2 with high affinity, and inhibited transmembrane signaling as demonstrated by inhibition of Fc receptor factor gamma 1/gamma 2 and interferon-stimulated gene factor-3 formation as well as inhibition of the IFN alpha antiviral response. Among viral host response modifiers, the B18R protein is unique inasmuch as it exists as a soluble extracellular as well as a cell surface protein and thus should effectively block both autocrine and paracrine functions of IFN.
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Affiliation(s)
- O R Colamonici
- Department of Pathology, University of Tennessee, Memphis 38163, USA
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