151
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McCart JA, Mehta N, Scollard D, Reilly RM, Carrasquillo JA, Tang N, Deng H, Miller M, Xu H, Libutti SK, Alexander HR, Bartlett DL. Oncolytic vaccinia virus expressing the human somatostatin receptor SSTR2: molecular imaging after systemic delivery using 111In-pentetreotide. Mol Ther 2005; 10:553-61. [PMID: 15336655 DOI: 10.1016/j.ymthe.2004.06.158] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 06/07/2004] [Accepted: 06/09/2004] [Indexed: 11/22/2022] Open
Abstract
Oncolytic vaccinia viruses (VV) have demonstrated tumor specificity, high levels of transgene expression, and anti-tumor effects. The ability to visualize vector biodistribution noninvasively will be necessary as gene therapy vectors come to clinical trials, and the creation of a VV that can both treat tumors and permit noninvasive imaging after systemic delivery is therefore an exciting concept. To facilitate imaging, a VV expressing the human somatostatin receptor type 2 (SSTR2) was created. Cells infected with the SSTR2-expressing VV or controls were incubated with the somatostatin analog 111In-pentetreotide with or without an excess of nonradiolabeled pentetreotide. The SSTR2-infected cells bound 111In-pentetreotide sixfold more efficiently than control virus-infected cells and this binding was specifically blocked by nonradiolabeled pentetreotide. Nude mice bearing subcutaneous murine colon CA xenografts were injected intraperitoneally with the SSTR2-expressing VV or control VV. After 6 days, mice were injected with 111In-pentetreotide and imaged. Mice were sacrificed and organs collected and counted in a gamma counter. The uptake of radioactivity in tumors and normal tissues (percentage injected dose per gram) and tumor-to-normal tissue ratios were determined. Tumors infected with the SSTR2-expressing VV accumulated significantly higher concentrations of radioactivity compared to tumors in animals receiving the control virus. SSTR2-infected tumors were visible on imaging 6 days after VV injection and could be visualized for up to 3 weeks post-viral injection using repeat injections of 111In-pentetreotide. This reporter gene imaging strategy could be a very effective method to visualize vector distribution, expression, and persistence over time and enhances the potential of VV as a novel anti-cancer therapeutic.
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Affiliation(s)
- J Andrea McCart
- Division of Experimental Therapeutics, Toronto General Research Institute, Toronto, ON, Canada.
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152
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Pendleton AR, Machamer CE. Differential localization and turnover of infectious bronchitis virus 3b protein in mammalian versus avian cells. Virology 2005; 345:337-45. [PMID: 16298409 PMCID: PMC7111863 DOI: 10.1016/j.virol.2005.09.069] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2005] [Revised: 09/15/2005] [Accepted: 09/22/2005] [Indexed: 12/24/2022]
Abstract
Infectious bronchitis virus (IBV) 3b protein is highly conserved among group 3 coronaviruses, suggesting that it is important for infection. A previous report (Virology 2003, 311:16-27) indicated that transfected IBV 3b localized to the nucleus in mammalian cells using a vaccinia-virus expression system. Although we confirmed these findings, we observed cytoplasmic localization of IBV 3b with apparent exclusion from the nucleus in avian cells (IBV normally infects chickens). IBV 3b was virtually undetectable by microscopy in mammalian cells transfected without vaccinia virus and in IBV-infected mammalian cells because of a greatly reduced half-life in these cells. A proteasome inhibitor stabilized IBV 3b in mammalian cells, but had little effect on IBV 3b in avian cells, suggesting that rapid turnover of IBV 3b in mammalian cells is proteasome-dependent while turnover in avian cells may be proteasome-independent. Our results highlight the importance of using cells derived from the natural host when studying coronavirus non-structural proteins.
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Affiliation(s)
- Amanda R Pendleton
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA
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153
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Herrero-Martínez E, Roberts KL, Hollinshead M, Smith GL. Vaccinia virus intracellular enveloped virions move to the cell periphery on microtubules in the absence of the A36R protein. J Gen Virol 2005; 86:2961-2968. [PMID: 16227217 DOI: 10.1099/vir.0.81260-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vaccinia virus (VACV) intracellular enveloped virus (IEV) particles are transported to the cell periphery on microtubules where they fuse with the plasma membrane to form cell-associated enveloped virus (CEV). Two IEV-specific proteins, F12L and A36R, are implicated in mediating transport of IEV. Without F12L, virus morphogenesis halts after formation of IEV, and CEV is not formed, whereas without A36R, IEV was reported not to be transported, yet CEV was formed, To address the roles of A36R and F12L in IEV transport, viruses with deletions of either F12L (vΔF12L) or A36R (vΔA36R) were labelled with enhanced green fluorescent protein (EGFP) fused to the core protein A5L, and used to follow CEV production with time. Without F12L, CEV production was inhibited by >99 %, whereas without A36R, CEV were produced at ∼60 % of wild-type levels at 24 h post-infection. Depolymerization of microtubules, but not actin, inhibited CEV formation in vΔA36R-infected cells. Moreover, vΔA36R IEV labelled with EGFP fused to the B5R protein co-localized with microtubules, showing that the A36R protein is not required for the interaction of IEV with microtubules. Time-lapse confocal microscopy confirmed that both wild-type and vΔA36R IEV moved in a stop–start manner at speeds consistent with microtubular movement, although the mean length of vΔA36R IEV movement was shorter. These data demonstrate that VACV IEV is transported to the cell surface using microtubules in the absence of A36R, and therefore IEV must attach to microtubule motors using at least one protein other than A36R.
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Affiliation(s)
- Esteban Herrero-Martínez
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Kim L Roberts
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Michael Hollinshead
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Geoffrey L Smith
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
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154
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Seo NS, Hocking AM, Höök M, McQuillan DJ. Decorin core protein secretion is regulated by N-linked oligosaccharide and glycosaminoglycan additions. J Biol Chem 2005; 280:42774-84. [PMID: 16258169 DOI: 10.1074/jbc.m511531200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of decorin using the vaccinia virus/T7 expression system resulted in secretion of two distinct glycoforms: a proteoglycan substituted with a single chondroitin sulfate chain and N-linked oligosaccharides and a core protein glycoform substituted with N-linked glycans but without a glycosaminoglycan chain. In this report, we have addressed two distinct questions. What is the rate-limiting step in glycosaminoglycan synthesis? Is glycosylation with either N-linked oligosaccharides or glycosaminoglycan required for secretion of decorin? N-terminal sequencing of the core protein glycoform, the addition of benzyl-beta-d-xyloside, and a UDP-xylose: core protein beta-d-xylosyltransferase activity assay show that xylosylation is a rate-limiting step in chondroitin sulfate biosynthesis. Decorin can be efficiently secreted with N-linked oligosaccharides alone or with a single chondroitin sulfate chain alone; however, there is severely impaired secretion of core protein devoid of any glycosylation. A decorin core protein mutant devoid of N-linked oligosaccharide attachment sites will not be secreted by Chinese hamster ovary cells deficient in xylosyltransferase or by parental Chinese hamster ovary wild type cells if the xylosyltransferase recognition sequence is disrupted. This finding suggests that quality control mechanisms sensitive to an absence of N-linked oligosaccharides can be abrogated by interaction of the core protein with the glycosaminoglycan synthetic machinery. We propose a model of regulation of decorin secretion that has several components, including appropriate substitution with N-linked oligosaccharides and factors involved in glycosaminoglycan synthesis.
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Affiliation(s)
- Neung-Seon Seo
- Center for Extracellular Matrix Biology, Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, Texas 77030, USA.
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155
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Abstract
The organization and sorting of proteins within the Golgi stack to establish and maintain its cis to trans polarization remains an enigma. The function of Golgi compartments involves coat assemblages that facilitate vesicle traffic, Rab-tether-SNAP receptor (SNARE) machineries that dictate membrane identity, as well as matrix components that maintain structure. We have investigated how the Golgi complex achieves compartmentalization in response to a key component of the coat complex I (COPI) coat assembly pathway, the ARF1 GTPase, in relationship to GTPases-regulating endoplasmic reticulum (ER) exit (Sar1) and targeting fusion (Rab1). Following collapse of the Golgi into the ER in response to inhibition of activation of ARF1 by Brefeldin A, we found that Sar1- and Rab1-dependent Golgi reformation took place at multiple peripheral and perinuclear ER exit sites. These rapidly converged into immature Golgi that appeared as onion-like structures composed of multiple concentrically arrayed cisternae of mixed enzyme composition. During clustering to the perinuclear region, Golgi enzymes were sorted to achieve the degree of polarization within the stack found in mature Golgi. Surprisingly, we found that sorting of Golgi enzymes into their subcompartments was insensitive to the dominant negative GTP-restricted ARF1 mutant, a potent inhibitor of COPI coat disassembly and vesicular traffic. We suggest that a COPI-independent, Rab-dependent mechanism is involved in the rapid reorganization of resident enzymes within the Golgi stack following synchronized release from the ER, suggesting an important role for Rab hubs in directing Golgi polarization.
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Affiliation(s)
- Serguei I Bannykh
- Department of Pathology, Yale University Medical School, 310 Cedar Street, New Haven, CT 06520, USA
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156
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Townsley AC, Senkevich TG, Moss B. The product of the vaccinia virus L5R gene is a fourth membrane protein encoded by all poxviruses that is required for cell entry and cell-cell fusion. J Virol 2005; 79:10988-98. [PMID: 16103150 PMCID: PMC1193616 DOI: 10.1128/jvi.79.17.10988-10998.2005] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The L5R gene of vaccinia virus is conserved among all sequenced members of the Poxviridae but has no predicted function or recognized nonpoxvirus homolog. Here we provide the initial characterization of the L5 protein. L5 is expressed following DNA replication with kinetics typical of a viral late protein, contains a single intramolecular disulfide bond formed by the virus-encoded cytoplasmic redox pathway, and is incorporated into intracellular mature virus particles, where it is exposed on the membrane surface. To determine whether L5 is essential for virus replication, we constructed a mutant that synthesizes L5 only in the presence of an inducer. The mutant exhibited a conditional-lethal phenotype, as cell-to-cell virus spread and formation of infectious progeny were dependent on the inducer. Nevertheless, all stages of replication occurred in the absence of inducer and intracellular and extracellular progeny virions appeared morphologically normal. Noninfectious virions lacking L5 could bind to cells, but the cores did not enter the cytoplasm. In addition, virions lacking L5 were unable to mediate low-pH-triggered cell-cell fusion from within or without. The phenotype of the L5R conditional lethal mutant is identical to that of recently described mutants in which expression of the A21, A28, and H2 genes is repressed. Thus, L5 is the fourth component of the poxvirus cell entry/fusion apparatus that is required for entry of both the intracellular and extracellular infectious forms of vaccinia virus.
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Affiliation(s)
- Alan C Townsley
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-0445, USA
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157
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Gao M, Brufatto N, Chen T, Murley LL, Thalakada R, Domagala M, Beattie B, Mamelak D, Athanasopoulos V, Johnson D, McFadden G, Burks C, Frappier L. Expression Profiling of Herpesvirus and Vaccinia Virus Proteins Using a High-Throughput Baculovirus Screening System. J Proteome Res 2005; 4:2225-35. [PMID: 16335970 DOI: 10.1021/pr050137u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have developed a high-throughput system for generating baculoviruses and testing the expression, solubility, and affinity column purification of encoded proteins. We have used this system to generate baculoviruses for and analyze the expression of 337 proteins from three different herpesviruses (HSV-1, EBV, and CMV) and vaccinia virus. Subsets of these proteins were also tested for expression and solubility in E. coli. Comparisons of the results in the two systems are presented for each virus.
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Affiliation(s)
- Mian Gao
- Affinium Pharmaceuticals, Toronto, Canada
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158
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Kwon JA, Rich A. Biological function of the vaccinia virus Z-DNA-binding protein E3L: gene transactivation and antiapoptotic activity in HeLa cells. Proc Natl Acad Sci U S A 2005; 102:12759-64. [PMID: 16126896 PMCID: PMC1200295 DOI: 10.1073/pnas.0506011102] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The vaccinia virus (VV) E3L protein is essential for virulence and has anti-apoptotic activity. In mice, Z-DNA-binding activity of the N-terminal domain of E3L (Z alpha) is necessary for viral lethality. Here, we report that inhibition of hygromycin-B-induced apoptosis in HeLa cells depends on Z-DNA binding of the E3L Z alpha domain. Z-DNA-binding domains of other proteins are equally effective in blocking apoptosis. Using a transient reporter assay, we demonstrate transactivation of human IL-6, nuclear factor of activated T cells (NF-AT), and p53 genes by E3L. This activation also requires Z-DNA binding of the N-terminal domain of E3L. Overall, this work suggests that the important role of E3L in VV pathogenesis involves modulating expression of host cellular genes at the transcriptional level and inhibiting apoptosis of host cells through Z-DNA binding.
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Affiliation(s)
- Jin-Ah Kwon
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 68-233, Cambridge, MA 02139-4307, USA.
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159
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Reeves PM, Bommarius B, Lebeis S, McNulty S, Christensen J, Swimm A, Chahroudi A, Chavan R, Feinberg MB, Veach D, Bornmann W, Sherman M, Kalman D. Disabling poxvirus pathogenesis by inhibition of Abl-family tyrosine kinases. Nat Med 2005; 11:731-9. [PMID: 15980865 DOI: 10.1038/nm1265] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2004] [Accepted: 06/02/2005] [Indexed: 11/09/2022]
Abstract
The Poxviridae family members vaccinia and variola virus enter mammalian cells, replicate outside the nucleus and produce virions that travel to the cell surface along microtubules, fuse with the plasma membrane and egress from infected cells toward apposing cells on actin-filled membranous protrusions. We show that cell-associated enveloped virions (CEV) use Abl- and Src-family tyrosine kinases for actin motility, and that these kinases act in a redundant fashion, perhaps permitting motility in a greater range of cell types. Additionally, release of CEV from the cell requires Abl- but not Src-family tyrosine kinases, and is blocked by STI-571 (Gleevec), an Abl-family kinase inhibitor used to treat chronic myelogenous leukemia in humans. Finally, we show that STI-571 reduces viral dissemination by five orders of magnitude and promotes survival in infected mice, suggesting possible use for this drug in treating smallpox or complications associated with vaccination. This therapeutic approach may prove generally efficacious in treating microbial infections that rely on host tyrosine kinases, and, because the drug targets host but not viral molecules, this strategy is much less likely to engender resistance compared to conventional antimicrobial therapies.
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Affiliation(s)
- Patrick M Reeves
- Microbiology and Molecular Genetics Graduate Program, Emory University School of Medicine, 615 Michael Street, Whitehead Research Building #144, Atlanta, Georgia 30322, USA
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160
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Abstract
In an attempt to produce a protein that will allow determination of the native human immunodeficiency virus type 1 (HIV-1) gp120 (Env) structure in its trimeric state, we fused the globular head of gp120 to the stalk region of influenza virus A (X31) hemagglutinin (HA). The chimeric protein (EnvHA) has been expressed by using a recombinant vaccinia virus system, and its functional characteristics were determined. EnvHA is expressed as a 120- to 150-kDa protein that can oligomerize to form dimers and trimers. It retains the low-pH (5.2 to 5.4) requirement of X31-HA to trigger membrane fusion but, unlike X31-HA, it is not absolutely dependent on exogenously added trypsin for protein processing to release the HA2 fusion peptide. In terms of receptor binding the chimeric protein retains specificity for human CD4 but, in relation to the membrane fusion event, it appears to lose the Env coreceptor specificity of the parental HIV-1 strains: NL43 for CXCR4 and JRFL for CCR5. These properties suggest that stable, functional EnvHAs are being produced and that they may be exploited in terms of structural studies. Further, the potential of introducing the envHA genes into influenza viruses, by use of reverse genetics, and their use as a therapeutic vaccine for HIV are discussed.
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Affiliation(s)
- K M Copeland
- Division of Virology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom.
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161
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Ahmed CMI, Burkhart MA, Subramaniam PS, Mujtaba MG, Johnson HM. Peptide mimetics of gamma interferon possess antiviral properties against vaccinia virus and other viruses in the presence of poxvirus B8R protein. J Virol 2005; 79:5632-9. [PMID: 15827178 PMCID: PMC1082775 DOI: 10.1128/jvi.79.9.5632-5639.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We have developed peptide mimetics of gamma interferon (IFN-gamma) that play a direct role in the activation and nuclear translocation of STAT1alpha transcription factor. These mimetics do not act through recognition by the extracellular domain of IFN-gamma receptor but rather bind to the cytoplasmic domain of the receptor chain 1, IFNGR-1, and thereby initiate the cellular signaling. Thus, we hypothesized that these mimetics would bypass the poxvirus virulence factor B8R protein that binds to intact IFN-gamma and prevents its interaction with the receptor. Human and murine IFN-gamma mimetic peptides were introduced into an adenoviral vector for intracellular expression. Murine IFN-gamma mimetic peptide was also expressed via chemical synthesis with an attached lipophilic group for penetration of cell plasma membrane. In contrast to intact human IFN-gamma, the mimetics did not bind poxvirus B8R protein, a homolog of the IFN-gamma receptor extracellular domain. Expression of B8R protein in WISH cells did not block the antiviral effect of the mimetics against encephalomyocarditis or vesicular stomatitis virus, while the antiviral activity of human IFN-gamma was neutralized. Consistent with the antiviral activity, the upregulation of MHC class I molecules on WISH cells by the IFN-gamma mimetics was not affected by B8R protein, while IFN-gamma-induced upregulation was blocked. Finally, the mimetics, but not IFN-gamma, inhibited vaccinia virus replication in African green monkey kidney BSC-40 cells. The data presented demonstrate that small peptide mimetics of IFN-gamma can avoid the B8R virulence factor for poxviruses and, thus, are potential candidates for antivirals against smallpox virus.
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Affiliation(s)
- Chulbul M I Ahmed
- University of Florida, Department of Microbiology and Cell Science, Building 981, Room 1052, P.O. Box 110700, Gainesville, FL 32611-0700, USA.
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162
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Chan KS, Verardi PH, Legrand FA, Yilma TD. Nef from pathogenic simian immunodeficiency virus is a negative factor for vaccinia virus. Proc Natl Acad Sci U S A 2005; 102:8734-9. [PMID: 15930136 PMCID: PMC1142211 DOI: 10.1073/pnas.0503542102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The nef gene of human and simian immunodeficiency viruses (HIV and SIV) is important for pathogenicity and maintenance of high virus loads. We previously reported that recombinant vaccinia viruses (rVVs) expressing nef from attenuated SIVmac1A11 (vNef1A11) produced typical plaques on thymidine kinase-deficient 143B cells, whereas rVVs expressing nef derived from the pathogenic SIVmac239 (vNef157) formed plaques with altered morphology. Here, we show that vNef157 is attenuated in normal and nude mice, whereas the pathogenicity of vNef1A11 is similar to that of a control virus. Thus, Nef157 is an attenuating factor in the vaccinia virus (VV) system, contrasting sharply with its function in lentiviruses. We also show that Nef157 inhibits VV cell-to-cell spread, causing formation of atypical plaques regardless of thymidine kinase deficiency, neoplasticity, and species of the infected cell line. We hypothesized that Nef157 interferes with VV spread by association with actin, but no direct colocalization of Nef and the cytoskeletal actin network was detected. Instead, higher levels of Nef157 protein were observed, although mRNAs for both nef genes were produced at comparable levels. Thus, the mechanism behind such Nef157 protein accumulation and Nef157-mediated VV attenuation could be related to the process that causes an opposite effect in its native SIV system, making SIVmac239 more pathogenic than SIVmac1A11.
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Affiliation(s)
- Kenneth S Chan
- International Laboratory of Molecular Biology for Tropical Disease Agents, Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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163
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Abstract
Production of recombinant proteins with the vaccinia virus expression system in five mammalian cell lines (HeLa, BS-C-1, Vero, MRC-5, and 293) was investigated for protein yield and proper posttranslational modifications. Regulatory acceptance of the host cell line was taken into consideration, where Vero, MRC-5, and 293 were considered more acceptable to the regulatory authorities. Relevant process knowledge for ease of scale-up with the particular cell type was also considered. Two proteins were expressed, enhanced green fluorescent protein (EGFP) in the cytoplasm and gp120, an HIV envelope coat protein that is secreted into the culture medium. HeLa cells produced the most EGFP at 17.2 microg/well with BS-C-1 and 293 following. BS-C-1 produced the most gp120 at 28.2 microg/mL with 293 and Vero following. Therefore, of the three most appropriate cell lines (Vero, MRC-5, and 293) for production processes, the best results were obtained with 293 cells. Although MRC-5 had a very high productivity on a per cell basis, the low cell density and slow growth rate made the overall production insufficient. Because gp120 contained a significant amount of posttranslational modification, this protein, produced by the different cell lines, was further analyzed by PNGase digestion suggesting N-linked glycosylation modifications in all cell lines tested. On the basis of these results and overall process considerations, 293 cells are recommended for further production process optimization in a serum-free suspension system.
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Affiliation(s)
- Nicole A Bleckwenn
- Biotechnology Unit, NIDDK, National Institutes of Health, DHHS, Bldg 14A Rm 173, 9000 Rockville Pike, Bethesda, Maryland 20892, USA
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164
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Osenkowski P, Meroueh SO, Pavel D, Mobashery S, Fridman R. Mutational and structural analyses of the hinge region of membrane type 1-matrix metalloproteinase and enzyme processing. J Biol Chem 2005; 280:26160-8. [PMID: 15901740 DOI: 10.1074/jbc.m414379200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Membrane type 1 (MT1)-matrix metalloproteinase (MMP) is a major mediator of collagen degradation in the pericellular space in both physiological and pathological conditions. Previous evidence has shown that on the cell surface, active MT1-MMP undergoes autocatalytic processing to a major membrane-tethered 44-kDa product lacking the catalytic domain and displaying Gly285 at its N terminus, which is at the beginning of the hinge domain. However, the importance of this site and the hinge region in MT1-MMP processing is unknown. In the current study, we generated mutations and deletions in the hinge of MT1-MMP and followed their effect on processing. These studies established Gly284-Gly285 as the main cleavage site involved in the formation of the 44-kDa species. However, alterations at this site did not prevent processing. Instead, they forced downstream cleavages within the stretch of residues flanked by Gln296 and Ser304 in the hinge region, as determined by the processing profile of various hinge deletion mutants. Also, replacement of the hinge of MT1-MMP with the longer MT3-MMP hinge did not prevent processing of MT1-MMP. Molecular dynamic studies using a computational model of MT1-MMP revealed that the hinge region is a highly motile element that undergoes significant motion in the highly exposed loop formed by Pro295-Arg302 consistent with being a prime target for proteolysis, in agreement with the mutational data. These studies suggest that the hinge of MT1-MMP evolved to facilitate processing, a promiscuous but compulsory event in the destiny of MT1-MMP, which may play a key role in the control of pericellular proteolysis.
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Affiliation(s)
- Pamela Osenkowski
- Department of Pathology, School of Medicine, Wayne State University, Detroit, Michigan 48201, USA
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165
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Coupar BEH, Goldie SG, Hyatt AD, Pallister JA. Identification of a Bohle iridovirus thymidine kinase gene and demonstration of activity using vaccinia virus. Arch Virol 2005; 150:1797-812. [PMID: 15883656 DOI: 10.1007/s00705-005-0544-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Accepted: 03/16/2005] [Indexed: 10/25/2022]
Abstract
In recent years interest in the family Iridoviridae has been renewed by the identification of a number of viruses, particularly from the genus Ranavirus, associated with disease in a range of poikilotherms. Ranaviruses have been isolated from amphibian, piscine and reptilian species. Here we describe an open reading frame (ORF) identified in the genome of Bohle iridovirus (BIV) which contains a nucleotide binding motif conserved within the thymidine kinase (TK) genes of iridoviruses from other genera (lymphocystis disease virus, LCDV, type species of the genus Lymphocystivirus; Chilo iridescent virus, CIV, type species of the genus Iridovirus). The ability of this putative gene to express a functional TK was confirmed by rescue of a TK negative mutant vaccinia virus in the presence of selective media, when expression was controlled by a vaccinia virus promoter. The sequence of the BIV TK was compared with the homologous sequences from epizootic haematopoietic necrosis virus (EHNV), a virus associated with disease in fish, from Wamena iridovirus (WIV) associated with systemic disease in green pythons, and from frog virus 3 (FV3) the ranavirus type species. Comparisons between these sequences and those available from other ranaviruses, other iridoviruses, other DNA viruses and cellular TKs are presented.
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Affiliation(s)
- B E H Coupar
- CSIRO Livestock Industries, Australian Animal Health Laboratory, Geelong, Vic., Australia.
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166
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Carter GC, Law M, Hollinshead M, Smith GL. Entry of the vaccinia virus intracellular mature virion and its interactions with glycosaminoglycans. J Gen Virol 2005; 86:1279-1290. [PMID: 15831938 DOI: 10.1099/vir.0.80831-0] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Vaccinia virus (VACV) produces two distinct enveloped virions, the intracellular mature virus (IMV) and the extracellular enveloped virus (EEV), but the entry mechanism of neither virion is understood. Here, the binding and entry of IMV particles have been investigated. The cell receptors for IMV are unknown, but it was proposed that IMV can bind to glycosaminoglycans (GAGs) on the cell surface and three IMV surface proteins have been implicated in this. In this study, the effect of soluble GAGs on IMV infectivity was reinvestigated and it was demonstrated that GAGs affected IMV infectivity partially in some cells, but not at all in others. Therefore, binding of IMV to GAGs is cell type-specific and not essential for IMV entry. By using electron microscopy, it is demonstrated that IMV from strains Western Reserve and modified virus Ankara enter cells by fusion with the plasma membrane. After an IMV particle bound to the cell, the IMV membrane fused with the plasma membrane and released the virus core into the cytoplasm. IMV surface antigen became incorporated into the plasma membrane and was not left outside the cell, as claimed in previous studies. Continuity between the IMV membrane and the plasma membrane was confirmed by tilt-series analysis to orientate membranes perpendicularly to the beam of the electron microscope. This analysis shows unequivocally that IMV is surrounded by a single lipid membrane and enters by fusion at the cell surface.
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Affiliation(s)
- Gemma C Carter
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Mansun Law
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Michael Hollinshead
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Geoffrey L Smith
- Department of Virology, Faculty of Medicine, Imperial College London, St Mary's Campus, Norfolk Place, London W2 1PG, UK
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167
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Abstract
Hydroxyurea (5 x 10(-3) M) inhibits the development of vaccinia virus in HeLa cells early after infection and prevents the synthesis of viral deoxyribonucleic acid. In the presence of hydroxyurea, late viral polypeptides are not formed, as observed by electrophoresis on polyacrylamide gels.
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168
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Abstract
The interferons (IFNs) are a family of cytokines with broad antiviral activities that also control cell proliferation and modulate immune responses. IFNs exert their pleiotropic actions through the regulation of multiple pathways that have been subjected to extensive study using diverse approaches. The scope of this review is to show how we can take advantage of vaccinia virus (VV) to study IFN-related pathways. We summarize and present the different VV models available for studying IFN function and the possibilities that they offer to analyze IFN-induced pathways, IFN modulators, and the biologic effects at the molecular and cellular levels. Emphasis is given to studies of dsRNA-activated signaling with VV lacking E3L (VV DeltaE3L) and in RNA-activated protein kinase (PKR)-related pathways, through the use of VV recombinants (VVr) with inducible PKR (VV PKR). The latest system is versatile, as expression of PKR can be regulated and induced at different times; similarly, VVr can be generated expressing other PKR modulators. As an example of the utility of VVr, we describe how this model has been used to analyze the antiviral and proapoptotic functions of PKR, the impact of PKR on translation, and the PKR-induced activation of the nuclear factor-kappaB (NF-kappaB) pathway.
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Affiliation(s)
- Jesús Gil
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, 28049 Madrid, Spain
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169
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Palacios S, Perez LH, Welsch S, Schleich S, Chmielarska K, Melchior F, Locker JK. Quantitative SUMO-1 modification of a vaccinia virus protein is required for its specific localization and prevents its self-association. Mol Biol Cell 2005; 16:2822-35. [PMID: 15800065 PMCID: PMC1142427 DOI: 10.1091/mbc.e04-11-1005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Vaccinia virus (VV), the prototype member of the Poxviridae, a family of large DNA viruses, carries out DNA replication in specialized cytoplasmic sites that are enclosed by the rough endoplasmic reticulum (ER). We show that the VV gene product of A40R is quantitatively modified by SUMO-1, which is required for its localization to the ER-enclosed replication sites. Expression of A40R lacking SUMO-1 induced the formation of rod-shaped cytoplasmic aggregates. The latter likely consisted of polymers of nonsumoylated protein, because unmodified A40R interacted with itself, but not with the SUMO-1-conjugated protein. Using a bacterial sumoylation system, we furthermore show that unmodified A40R is mostly insoluble, whereas the modified form is completely soluble. By electron microscopy, the A40R rods seen in cells were associated with the cytosolic side of the ER and induced the apposition of several ER cisternae. A40R is the first example of a poxvirus protein to acquire SUMO-1. Its quantitative SUMO-1 modification is required for its proper localization to the viral "mini-nuclei" and prevents its self-association. The ability of the nonsumoylated A40R to bring ER membranes close together could suggest a role in the fusion of ER cisternae when these coalesce to enclose the VV replication sites.
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Affiliation(s)
- Silvia Palacios
- European Molecular Biology Laboratory, Cell Biology and Biophysics Programme, 69117 Heidelberg, Germany
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170
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Yang H, Kim SK, Kim M, Reche PA, Morehead TJ, Damon IK, Welsh RM, Reinherz EL. Antiviral chemotherapy facilitates control of poxvirus infections through inhibition of cellular signal transduction. J Clin Invest 2005; 115:379-87. [PMID: 15690085 PMCID: PMC546427 DOI: 10.1172/jci23220] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Accepted: 11/23/2004] [Indexed: 01/22/2023] Open
Abstract
The EGF-like domain of smallpox growth factor (SPGF) targets human ErbB-1, inducing tyrosine phosphorylation of certain host cellular substrates via activation of the receptor's kinase domain and thereby facilitating viral replication. Given these findings, low molecular weight organic inhibitors of ErbB-1 kinases might function as antiviral agents against smallpox. Here we show that CI-1033 and related 4-anilinoquinazolines inhibit SPGF-induced human cellular DNA synthesis, protein tyrosine kinase activation, and c-Cbl association with ErbB-1 and resultant internalization. Infection of monkey kidney BSC-40 and VERO-E6 cells in vitro by variola strain Solaimen is blocked by CI-1033, primarily at the level of secondary viral spreading. In an in vivo lethal vaccinia virus pneumonia model, CI-1033 alone promotes survival of animals, augments systemic T cell immunity and, in conjunction with a single dose of anti-L1R intracellular mature virus particle-specific mAb, fosters virtually complete viral clearance of the lungs of infected mice by the eighth day after infection. Collectively, these findings show that chemical inhibitors of host-signaling pathways exploited by viral pathogens may represent potent antiviral therapies.
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Affiliation(s)
- Hailin Yang
- Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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171
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De Silva FS, Moss B. Origin-independent plasmid replication occurs in vaccinia virus cytoplasmic factories and requires all five known poxvirus replication factors. Virol J 2005; 2:23. [PMID: 15784143 PMCID: PMC1079961 DOI: 10.1186/1743-422x-2-23] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Accepted: 03/22/2005] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Replication of the vaccinia virus genome occurs in cytoplasmic factory areas and is dependent on the virus-encoded DNA polymerase and at least four additional viral proteins. DNA synthesis appears to start near the ends of the genome, but specific origin sequences have not been defined. Surprisingly, transfected circular DNA lacking specific viral sequences is also replicated in poxvirus-infected cells. Origin-independent plasmid replication depends on the viral DNA polymerase, but neither the number of additional viral proteins nor the site of replication has been determined. RESULTS Using a novel real-time polymerase chain reaction assay, we detected a >400-fold increase in newly replicated plasmid in cells infected with vaccinia virus. Studies with conditional lethal mutants of vaccinia virus indicated that each of the five proteins known to be required for viral genome replication was also required for plasmid replication. The intracellular site of replication was determined using a plasmid containing 256 repeats of the Escherichia coli lac operator and staining with an E. coli lac repressor-maltose binding fusion protein followed by an antibody to the maltose binding protein. The lac operator plasmid was localized in cytoplasmic viral factories delineated by DNA staining and binding of antibody to the viral uracil DNA glycosylase, an essential replication protein. In addition, replication of the lac operator plasmid was visualized continuously in living cells infected with a recombinant vaccinia virus that expresses the lac repressor fused to enhanced green fluorescent protein. Discrete cytoplasmic fluorescence was detected in cytoplasmic juxtanuclear sites at 6 h after infection and the area and intensity of fluorescence increased over the next several hours. CONCLUSION Replication of a circular plasmid lacking specific poxvirus DNA sequences mimics viral genome replication by occurring in cytoplasmic viral factories and requiring all five known viral replication proteins. Therefore, small plasmids may be used as surrogates for the large poxvirus genome to study trans-acting factors and mechanism of viral DNA replication.
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Affiliation(s)
- Frank S De Silva
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA
| | - Bernard Moss
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA
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172
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Stack J, Haga IR, Schröder M, Bartlett NW, Maloney G, Reading PC, Fitzgerald KA, Smith GL, Bowie AG. Vaccinia virus protein A46R targets multiple Toll-like-interleukin-1 receptor adaptors and contributes to virulence. ACTA ACUST UNITED AC 2005; 201:1007-18. [PMID: 15767367 PMCID: PMC2213104 DOI: 10.1084/jem.20041442] [Citation(s) in RCA: 285] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Viral immune evasion strategies target key aspects of the host antiviral response. Recently, it has been recognized that Toll-like receptors (TLRs) have a role in innate defense against viruses. Here, we define the function of the vaccinia virus (VV) protein A46R and show it inhibits intracellular signalling by a range of TLRs. TLR signalling is triggered by homotypic interactions between the Toll-like–interleukin-1 resistance (TIR) domains of the receptors and adaptor molecules. A46R contains a TIR domain and is the only viral TIR domain–containing protein identified to date. We demonstrate that A46R targets the host TIR adaptors myeloid differentiation factor 88 (MyD88), MyD88 adaptor-like, TIR domain–containing adaptor inducing IFN-β (TRIF), and the TRIF-related adaptor molecule and thereby interferes with downstream activation of mitogen-activated protein kinases and nuclear factor κB. TRIF mediates activation of interferon (IFN) regulatory factor 3 (IRF3) and induction of IFN-β by TLR3 and TLR4 and suppresses VV replication in macrophages. Here, A46R disrupted TRIF-induced IRF3 activation and induction of the TRIF-dependent gene regulated on activation, normal T cell expressed and secreted. Furthermore, we show that A46R is functionally distinct from another described VV TLR inhibitor, A52R. Importantly, VV lacking the A46R gene was attenuated in a murine intranasal model, demonstrating the importance of A46R for VV virulence.
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MESH Headings
- ATP-Binding Cassette Transporters
- Adaptor Proteins, Signal Transducing
- Adaptor Proteins, Vesicular Transport/metabolism
- Amino Acid Sequence
- Animals
- Antigens, Differentiation/metabolism
- Cell Line
- DNA-Binding Proteins/metabolism
- Disease Models, Animal
- Gene Expression Regulation, Viral/genetics
- Gene Expression Regulation, Viral/physiology
- Humans
- Interferon Regulatory Factor-3
- Interferon-beta/biosynthesis
- Lymphocyte Activation/genetics
- Lymphocyte Activation/physiology
- MAP Kinase Signaling System/genetics
- MAP Kinase Signaling System/physiology
- Membrane Glycoproteins/metabolism
- Mice
- Molecular Sequence Data
- Myeloid Differentiation Factor 88
- Periplasmic Binding Proteins
- Protein Structure, Tertiary/genetics
- Protein Structure, Tertiary/physiology
- Receptors, Cell Surface/metabolism
- Receptors, Immunologic/metabolism
- T-Lymphocytes/physiology
- Toll-Like Receptor 3
- Toll-Like Receptor 4
- Toll-Like Receptors
- Transcription Factors/metabolism
- Vaccinia virus/genetics
- Vaccinia virus/metabolism
- Vaccinia virus/pathogenicity
- Viral Proteins/genetics
- Viral Proteins/metabolism
- Virus Diseases/genetics
- Virus Diseases/physiopathology
- Virus Replication/genetics
- Virus Replication/physiology
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Affiliation(s)
- Julianne Stack
- Department of Biochemistry, Trinity College, Dublin 2, Ireland
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173
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Perales C, Carrasco L, González ME. Regulation of HIV-1 env mRNA translation by Rev protein. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research 2005; 1743:169-75. [PMID: 15777852 DOI: 10.1016/j.bbamcr.2004.09.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2003] [Revised: 07/20/2004] [Accepted: 09/24/2004] [Indexed: 11/21/2022]
Abstract
We have examined the effect of Rev on the regulation of the expression of RRE containing mRNAs when they were synthesised in the nucleus or directly in the cytoplasm. In the nuclear expression system, Rev enhanced env mRNA transport by about 1.6-fold, while translation of this mRNA was increased more than a 100-fold. These findings indicate that the target of Rev activity is located mainly at the translational level. Synthesis of Env using a recombinant vaccinia virus system, which synthesised env mRNA directly in the cytoplasm, is also enhanced by Rev. Finally, RRE functioning was examined using a luciferase mRNA bearing this element. Rev stimulated the synthesis of Luciferase both when the luc mRNA was made in the nucleus or in cytoplasm. Our results indicate that the effect of Rev on env mRNA transport is low compared with the enhancement of translation of this mRNA.
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Affiliation(s)
- Celia Perales
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
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174
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Byrd CM, Hruby DE. A conditional-lethal vaccinia virus mutant demonstrates that the I7L gene product is required for virion morphogenesis. Virol J 2005; 2:4. [PMID: 15701171 PMCID: PMC548685 DOI: 10.1186/1743-422x-2-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Accepted: 02/08/2005] [Indexed: 11/12/2022] Open
Abstract
A conditional-lethal recombinant virus was constructed in which the expression of the vaccinia virus I7L gene is under the control of the tetracycline operator/repressor system. In the absence of I7L expression, processing of the major VV core proteins is inhibited and electron microscopy reveals defects in virion morphogenesis subsequent to the formation of immature virion particles but prior to core condensation. Plasmid-borne I7L is capable of rescuing the growth of this virus and rescue is optimal when the I7L gene is expressed using the authentic I7L promoter. Taken together, these data suggest that correct temporal expression of the VV I7L cysteine proteinase is required for core protein maturation, virion assembly and production of infectious progeny.
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Affiliation(s)
- Chelsea M Byrd
- Molecular and Cellular Biology Program, Oregon State University, 220 Nash Hall, Corvallis, Oregon, 97331 USA
| | - Dennis E Hruby
- Molecular and Cellular Biology Program, Oregon State University, 220 Nash Hall, Corvallis, Oregon, 97331 USA
- Department of Microbiology, Oregon State University, 220 Nash Hall, Corvallis, Oregon, 97331
USA
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175
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Dellis S, Strickland KC, McCrary WJ, Patel A, Stocum E, Wright CF. Protein interactions among the vaccinia virus late transcription factors. Virology 2005; 329:328-36. [PMID: 15518812 DOI: 10.1016/j.virol.2004.08.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Revised: 07/23/2004] [Accepted: 08/17/2004] [Indexed: 11/18/2022]
Abstract
The viral proteins A1L, A2L, G8R, and H5R positively modulate vaccinia virus late gene expression. Host-encoded proteins hnRNP A2 and RBM3 may also interact with these viral factors to influence late gene expression. In these studies, a yeast two-hybrid screen and in vitro pulldown and crosslinking experiments were used to investigate protein--protein interactions among these factors. These studies confirmed a previous observation that G8R interacts with itself and A1L. However, self-interactions of A1L and H5R, and interactions between A2L and G8R, A2L and H5R, and H5R and G8R were also observed. In addition, the proteins hnRNP A2 and RBM3 both showed some interaction with A2L. Illustration of these interactions is a step toward understanding the architecture of the late gene transcription complex as it occurs in poxviruses.
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Affiliation(s)
- Stephanie Dellis
- Biology Department, College of Charleston, Charleston, SC 29401, USA
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176
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Szajner P, Jaffe H, Weisberg AS, Moss B. A complex of seven vaccinia virus proteins conserved in all chordopoxviruses is required for the association of membranes and viroplasm to form immature virions. Virology 2005; 330:447-59. [PMID: 15567438 DOI: 10.1016/j.virol.2004.10.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Revised: 09/28/2004] [Accepted: 10/05/2004] [Indexed: 10/26/2022]
Abstract
Early events in vaccinia virus (VAC) morphogenesis, particularly the formation of viral membranes and their association with viroplasm, are poorly understood. Recently, we showed that repression of A30 or G7 expression results in the accumulation of normal viral membranes that form empty-looking immature virions (IV), which are separated from large masses of electron-dense viroplasm. In addition, A30 and G7 physically and functionally interact with each other and with the F10 protein kinase. To identify other proteins involved in early morphogenesis, proteins from cells that had been infected with vaccinia virus expressing an epitope-tagged copy of F10 were purified by immunoaffinity chromatography and analyzed by gel electrophoresis. In addition to F10, A30, and G7, viral proteins A15, D2, D3, and J1 were identified by mass spectrometry of tryptic peptides. Further evidence for the complex was obtained by immunopurification of proteins associated with epitope-tagged A15, D2, and D3. The previously unstudied A15, like other proteins in the complex, was expressed late in infection, associated with virus cores, and required for the stability and kinase activity of F10. Biochemical and electron microscopic analyses indicated that mutants in which A15 or D2 expression was regulated by the Escherichia coli lac operator system exhibited phenotypes characterized by the presence of large numbers of empty immature virions, similar to the results obtained with inducible A30 and G7 mutants. Empty immature virions were also seen by electron microscopy of cells infected with temperature-sensitive mutants of D2 or D3, though the numbers of membrane forms were reduced perhaps due to additional effects of high temperature.
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Affiliation(s)
- Patricia Szajner
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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177
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Tscharke DC, Karupiah G, Zhou J, Palmore T, Irvine KR, Haeryfar SMM, Williams S, Sidney J, Sette A, Bennink JR, Yewdell JW. Identification of poxvirus CD8+ T cell determinants to enable rational design and characterization of smallpox vaccines. ACTA ACUST UNITED AC 2004; 201:95-104. [PMID: 15623576 PMCID: PMC2212779 DOI: 10.1084/jem.20041912] [Citation(s) in RCA: 260] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The large size of poxvirus genomes has stymied attempts to identify determinants recognized by CD8+ T cells and greatly impeded development of mouse smallpox vaccination models. Here, we use a vaccinia virus (VACV) expression library containing each of the predicted 258 open reading frames to identify five peptide determinants that account for approximately half of the VACV-specific CD8+ T cell response in C57BL/6 mice. We show that the primary immunodominance hierarchy is greatly affected by the route of VACV infection and the poxvirus strain used. Modified vaccinia virus ankara (MVA), a candidate replacement smallpox vaccine, failed to induce responses to two of the defined determinants. This could not be predicted by genomic comparison of viruses and is not due strictly to limited MVA replication in mice. Several determinants are immunogenic in cowpox and ectromelia (mousepox) virus infections, and immunization with the immunodominant determinant provided significant protection against lethal mousepox. These findings have important implications for understanding poxvirus immunity in animal models and bench-marking immune responses to poxvirus vaccines in humans.
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Affiliation(s)
- David C Tscharke
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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178
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Yarovinsky F, Andersen JF, King LR, Caspar P, Aliberti J, Golding H, Sher A. Structural Determinants of the Anti-HIV Activity of a CCR5 Antagonist Derived from Toxoplasma gondii. J Biol Chem 2004; 279:53635-42. [PMID: 15469936 DOI: 10.1074/jbc.m410550200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protozoan parasite Toxoplasma gondii possesses a protein, cyclophilin-18 (C-18), which binds to the chemokine receptor CCR5, induces interleukin-12 production from murine dendritic cells, and inhibits fusion and infectivity of human immunodeficiency virus 1 (HIV-1) R5 viruses by co-receptor antagonism. Site-directed mutagenesis was employed to identify the domains in C-18 responsible for its CCR5 binding and antiviral functions. To do so we focused on amino acid differences with Plasmodium falciparum cyclophilin, which, although 53% identical with C-18, has minimal binding activity for CCR5, and we generated 22 mutants with substitutions in the regions of non-homology located on the putative surface of the molecule. Two mutations situated on the face of C-18, predicted to be involved in its interaction with the ligand cyclosporin A, were shown to be critical for CCR5-binding and the inhibition of HIV-1 fusion and infectivity. In contrast, four mutations in C-18 specifically designed to abolish the peptidyl-prolyl cis-trans-isomerase activity of the protein failed to inactivate its CCR5 binding and HIV inhibitory activities. Interleukin-12 induction by C-18, on the other hand, was abrogated by mutations effecting either the CCR5 binding or enzymatic function of the molecule. These findings shed light on the structural basis of the molecular mimicry of the chemokine function by a pathogen-derived protein and provide a basis for further modification of C-18 into an antiviral agent.
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Affiliation(s)
- Felix Yarovinsky
- Immunobiology Section, Laboratory of Parasitic Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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179
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Hsiao JC, Chung CS, Drillien R, Chang W. The cowpox virus host range gene, CP77, affects phosphorylation of eIF2 alpha and vaccinia viral translation in apoptotic HeLa cells. Virology 2004; 329:199-212. [PMID: 15476887 DOI: 10.1016/j.virol.2004.07.032] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2004] [Revised: 04/09/2004] [Accepted: 07/12/2004] [Indexed: 10/26/2022]
Abstract
Host restriction of vaccinia virus has been previously described in CHO and RK13 cells in which a cowpox virus CP77 gene rescues vaccinia virus growth at the viral protein translation level. Here we investigate the restrictive stage of vaccinia virus in HeLa cells using a vaccinia mutant virus (VV-hr) that contains a deletion of 18-kb genome sequences resulting in no growth in HeLa cells. Insertion of CP77 gene into VV-hr generated a recombinant virus (VV-36hr) that multiplied well in HeLa cells. Both viruses could enter cells, initiate viral DNA replication and intermediate gene transcription. However, translation of viral intermediate gene was only detected in cells infected with VV-36hr, indicating that CP77 relieves host restriction at the intermediate gene translation stage in HeLa cells. Caspase-2 and -3 activation was observed in HeLa cells infected with VV-hr coupled with dramatic morphological alterations and cleavage of the translation initiation factor eIF4G. Caspase activation was reduced in HeLa cells infected with VV-36hr, indicating that CP77 acts upstream of caspase activation. Enhanced phosphorylation of PKR and eIF2alpha was also observed in cells infected with VV-hr and was suppressed by CP77. Suppression of eIF4G cleavage with the caspase inhibitor ZVAD did not rescue virus translation, whereas expression of a mutant eIF2alpha protein with an alanine substitution of serine at amino acid position 51 (eIF2alphaS51A) partially restored viral translation and moderately increased virus growth in HeLa cells.
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Affiliation(s)
- Jye-Chian Hsiao
- Graduate Institute of Life Science, National Defense Medical Center, National Defense University, Taipei, Taiwan, ROC
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180
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Klyushnenkova EN, Ponniah S, Rodriguez A, Kodak J, Mann DL, Langerman A, Nishimura MI, Alexander RB. CD4 and CD8 T-lymphocyte recognition of prostate specific antigen in granulomatous prostatitis. J Immunother 2004; 27:136-46. [PMID: 14770085 DOI: 10.1097/00002371-200403000-00007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In order to develop immunotherapies for prostate cancer, many groups are exploring vaccination strategies to induce an immune response against prostate specific antigen (PSA). To determine if T-cell recognition of PSA might be a feature of a naturally occurring human disease, we have studied patients with prostatitis, a poorly understood clinical syndrome of men in which there is evidence that an immune response directed against the prostate may be occurring. We wished to determine if a T-cell response to PSA might be occurring in these patients. We generated long-term T-cell lines from peripheral blood mononuclear cells (PBMC) of one patient with granulomatous prostatitis using purified PSA as an antigen. Several CD4+ and CD8+ TcR alpha/beta+ T-cell lines were selected for PSA reactivity as measured by at least a threefold increase in IFN-gamma secretion in response to PSA presented by irradiated autologous PBMC. CD4 and CD8 T-cell lines recognized PSA in the context of HLA-DRbeta1*1501 and HLA-B*0702, respectively. The specificity and HLA restriction of the lines was confirmed using EBV-B cell lines infected with a recombinant PSA-expressing vaccinia virus and also engineered to express PSA by retroviral transfection. HLA-matched targets infected by control vector as well as HLA-mismatched PSA-expressing targets did not induce the response. The data demonstrate that PSA-specific T cells are present in the PBMC of this patient with granulomatous prostatitis, who may be manifesting naturally the type of immune response directed at the prostate that is the goal of prostate cancer immunotherapy. However, the Class I-restricted epitope has not yet been demonstrated to be expressed on the surface of prostate cancer cells. To our knowledge, this is the first demonstration of HLA-DRB1*1501- or HLA-B*0702-restricted responses to PSA and extends the number of HLA molecules accommodating the use of PSA antigen as a candidate vaccine for prostate cancer immunotherapy.
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181
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McShane H, Pathan AA, Sander CR, Keating SM, Gilbert SC, Huygen K, Fletcher HA, Hill AVS. Recombinant modified vaccinia virus Ankara expressing antigen 85A boosts BCG-primed and naturally acquired antimycobacterial immunity in humans. Nat Med 2004; 10:1240-4. [PMID: 15502839 DOI: 10.1038/nm1128] [Citation(s) in RCA: 463] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Accepted: 09/28/2004] [Indexed: 11/10/2022]
Abstract
Protective immunity against Mycobacterium tuberculosis depends on the generation of a T(H)1-type cellular immune response, characterized by the secretion of interferon-gamma (IFN-gamma) from antigen-specific T cells. The induction of potent cellular immune responses by vaccination in humans has proven difficult. Recombinant viral vectors, especially poxviruses and adenoviruses, are particularly effective at boosting previously primed CD4(+) and CD8(+) T-cell responses against a number of intracellular pathogens in animal studies. In the first phase 1 study of any candidate subunit vaccine against tuberculosis, recombinant modified vaccinia virus Ankara (MVA) expressing antigen 85A (MVA85A) was found to induce high levels of antigen-specific IFN-gamma-secreting T cells when used alone in bacille Calmette-Guerin (BCG)-naive healthy volunteers. In volunteers who had been vaccinated 0.5-38 years previously with BCG, substantially higher levels of antigen-specific IFN-gamma-secreting T cells were induced, and at 24 weeks after vaccination these levels were 5-30 times greater than in vaccinees administered a single BCG vaccination. Boosting vaccinations with MVA85A could offer a practical and efficient strategy for enhancing and prolonging antimycobacterial immunity in tuberculosis-endemic areas.
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Affiliation(s)
- Helen McShane
- Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Churchill Hospital, Oxford, OX3 7LJ, UK.
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182
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Abstract
Here we present a comprehensive molecular mapping of virus-induced autoimmune B cell responses obtained by serological identification of antigens by recombinant expression cloning analysis. Immunoscreening of cDNA expression libraries of various organs (lung, liver, and spleen) using sera from mice infected with cytopathic (vaccinia virus [VV]) or noncytopathic (lymphocytic choriomeningitis virus [LCMV]) viruses revealed a broad specificity of the elicited autoantibody response. Interestingly, the majority of the identified autoantigens have been previously described as autoantigens in humans. We found that induction of virus-induced autoantibodies of the immunoglobulin G class largely depends on the CD40–CD40L-mediated interaction between T and B cells. Furthermore, antibody titers against a number of autoantigens were comparable to the concomitantly induced antiviral antibody response. Comparison of serum reactivity against a selected panel of autoantigens after infection with VV, LCMV, or vesicular stomatitis virus showed that the different virus infections triggered distinct autoantibody responses, suggesting that virus infections may leave specific “autoantibody fingerprints” in the infected host.
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Affiliation(s)
- Burkhard Ludewig
- Department of Pathology, Institute of Experimental Immunology, University Hospital Zürich, CH-8091 Zürich, Switzerland.
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183
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Affiliation(s)
- Alan Hall
- MRC Laboratory for Molecular Cell Biology & Cell Biology Unit, University College, London WC1E 6BT, UK. alan.hall@ucl. ac.uk
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184
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Santos CR, Vega FM, Blanco S, Barcia R, Lazo PA. The vaccinia virus B1R kinase induces p53 downregulation by an Mdm2-dependent mechanism. Virology 2004; 328:254-65. [PMID: 15464845 DOI: 10.1016/j.virol.2004.08.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 07/10/2004] [Accepted: 08/13/2004] [Indexed: 12/20/2022]
Abstract
Poxvirus infection has a strong effect on cellular functions. To understand viral pathogenesis, it is necessary to know how viral proteins interact with host proteins. The B1R kinase is an early viral gene required for vaccinia virus DNA synthesis and replication, but no cellular substrate is known for this viral kinase. B1R is able to hyperphosphorylate p53 in several residues in the N-terminal transactivation domain, including Ser15 and Thr18. B1R does not phosphorylate Mdm2. B1R promotes an increase in p53 ubiquitination and a reduction of p53 acetylation by p300. The over-expressed B1R protein induces the degradation of p53 in a concentration-dependent manner and is lost when Ser15 and Th18 are changed to alanine or when the B1R kinase is inactivated by introducing the K149Q substitution. The B1R-induced downregulation of p53 requires Mdm2. The hyperphosphorylated p53 is transcriptionally active, and this activity also falls as B1R increases. The BAX gene promoter is more sensitive to this reduction of transcription than p21 or 14-3-3 gene promoters. This effect of B1R on p53 can be one of the mechanisms by which vaccinia virus exerts its role in infected cells.
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Affiliation(s)
- Cláudio R Santos
- Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas, Universidad de Salamanca, E-37007 Salamanca, Spain
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185
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Chun HH, Cary RB, Lansigan F, Whitelegge J, Rawlings DJ, Gatti RA. ATM protein purified from vaccinia virus expression system: DNA binding requirements for kinase activation. Biochem Biophys Res Commun 2004; 322:74-81. [PMID: 15313175 DOI: 10.1016/j.bbrc.2004.07.085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Indexed: 11/13/2022]
Abstract
The ataxia-telangiectasia mutated (ATM) gene product plays a role in responding to double stand DNA breaks. Some biochemical studies of ATM function have been hampered by lack of an efficient expression system and abundant purified ATM protein. We report the construction of a vaccinia virus expressing ATM, vWR-ATM, which was used to produce large amounts of functional FLAG-tagged ATM protein (FLAG-ATM) in HeLa cells. Kinase activity of the purified FLAG-ATM was dependent on manganese and inhibited with wortmannin. Using the FLAG-ATM recombinant protein, GST-p53 serine 15 phosphorylation increased in the presence of damaged DNA. PHAS-1 phosphorylation was found to be DNA independent. Purified FLAG-ATM was recovered in the autophosphorylated form, as demonstrated by phosphorylation of ATM serine 1981. As shown by atomic force microscopy, FLAG-ATM bound to linear DNA both at broken ends and in mid-strands. Vaccinia virus is the most efficient ATM expression system described to date.
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Affiliation(s)
- Helen H Chun
- Department of Pathology, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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186
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Li C, Xia Y, Gao X, Gershon PD. Mechanism of RNA 2'-O-methylation: evidence that the catalytic lysine acts to steer rather than deprotonate the target nucleophile. Biochemistry 2004; 43:5680-7. [PMID: 15134442 DOI: 10.1021/bi0359980] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The weight of current evidence suggests that RNA 2'-O-MTases employ an S(N)2 mechanism with an in-line attack of the target nucleophile upon the methyl group of the AdoMet cofactor. It has been suggested that, like the phosphohydrolytic enzymes, ribozymes, and nucleic acid polymerases, the RNA 2'-O-MTases initially activate the substrate's attacking hydroxyl oxygen by deprotonation. Here, evidence is presented that the vaccinia virus mRNA cap specific 2'-O-MTase VP39 does not promote RNA 2'-oxyanion formation but that instead it acts by steering a hydroxyl oxygen orbital toward the cofactor methyl center.
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Affiliation(s)
- C Li
- Department of Medical Biochemistry and Genetics/Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, Texas 77030, USA
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187
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Abstract
The 70-amino-acid A13L protein is a component of the vaccinia virus membrane. We demonstrate here that the protein is expressed at late times of infection, undergoes phosphorylation at a serine residue(s), and becomes encapsidated in a monomeric form. Phosphorylation is dependent on Ser40, which lies within the proline-rich motif SPPP. Because phosphorylation of the A13 protein is only minimally affected by disruption of the viral F10 kinase or H1 phosphatase, a cellular kinase is likely to be involved. We generated an inducible recombinant in which A13 protein expression is dependent upon the inclusion of tetracycline in the culture medium. Repression of the A13L protein spares the biochemical progression of the viral life cycle but arrests virion morphogenesis. Virion assembly progresses through the formation of immature virions (IVs); however, these virions do not acquire nucleoids, and DNA crystalloids accumulate in the cytoplasm. Further development into intracellular mature virions is blocked, causing a 1,000-fold decrease in the infectious virus yield relative to that obtained in the presence of the inducer. We also determined that the temperature-sensitive phenotype of the viral mutant Cts40 is due to a nucleotide transition within the A13L gene that causes a Thr(48)-->Ile substitution. This substitution disrupts the function of the A13 protein but does not cause thermolability of the protein; at the nonpermissive temperature, virion morphogenesis arrests at the stage of IV formation. The A13L protein, therefore, is part of a newly recognized group of membrane proteins that are dispensable for the early biogenesis of the virion membrane but are essential for virion maturation.
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Affiliation(s)
- Bethany Unger
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Rd., BSB-273, Milwaukee, WI 53226, USA
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188
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Seifert U, Liermann H, Racanelli V, Halenius A, Wiese M, Wedemeyer H, Ruppert T, Rispeter K, Henklein P, Sijts A, Hengel H, Kloetzel PM, Rehermann B. Hepatitis C virus mutation affects proteasomal epitope processing. J Clin Invest 2004; 114:250-9. [PMID: 15254592 PMCID: PMC449747 DOI: 10.1172/jci20985] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Accepted: 05/18/2004] [Indexed: 12/11/2022] Open
Abstract
The high incidence of hepatitis C virus (HCV) persistence raises the question of how HCV interferes with host immune responses. Studying a single-source HCV outbreak, we identified an HCV mutation that impaired correct carboxyterminal cleavage of an immunodominant HLA-A2-restricted CD8 cell epitope that is frequently recognized by recovered patients. The mutation, a conservative HCV nonstructural protein 3 (NS3) tyrosine to phenylalanine substitution, was absent in 54 clones of the infectious source, but present in 15/21 (71%) HLA-A2-positive and in 11/24 (46%) HLA-A2-negative patients with chronic hepatitis C. In order to analyze whether the mutation affected the processing of the HLA-A2-restricted CD8 cell epitope, mutant and wild-type NS3 polypeptides were digested in vitro with 20S constitutive proteasomes and with immunoproteasomes. The presence of the mutation resulted in impaired carboxyterminal cleavage of the epitope. In order to analyze whether impaired epitope processing affected T cell priming in vivo, HLA-A2-transgenic mice were infected with vaccinia viruses encoding either wild-type or mutant HCV NS3. The mutant induced fewer epitope-specific, IFN-gamma;-producing and fewer tetramer(+) cells than the wild type. These data demonstrate how a conservative mutation in the flanking region of an HCV epitope impairs the induction of epitope-specific CD8(+) T cells and reveal a mechanism that may contribute to viral sequence evolution in infected patients.
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Affiliation(s)
- Ulrike Seifert
- Institute of Biochemistry, Charité, Humboldt University, Berlin, Germany
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189
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Abstract
The large size of poxvirus virions (approx 250 x 350 nm) makes them ideal candidates for microscopic studies. Recombinant vaccinia viruses that express a viral envelope-specific, green fluorescent protein (GFP) chimera produce enveloped virions that fluoresce green. This fluorescent labeling allows the live, real-time study of viral egress using a variety of microscopic techniques. The methods presented here describe how to image the movement of intracellular enveloped virions that are labeled with green fluorescent protein using time-lapse laser scanning confocal microscopy. Details are also provided for analyzing the images obtained and converting them into QuickTime movies suitable for presentation.
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Affiliation(s)
- Brian M Ward
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
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190
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Abstract
The cascade of events that leads to vaccinia-induced actin polymerization requires Src-dependent tyrosine phosphorylation of the viral membrane protein A36R. We found that a localized outside-in signaling cascade induced by the viral membrane protein B5R is required to potently activate Src and induce A36R phosphorylation at the plasma membrane. In addition, Src-mediated phosphorylation of A36R regulated the ability of virus particles to recruit and release conventional kinesin. Thus, Src activity regulates the transition between cytoplasmic microtubule transport and actin-based motility at the plasma membrane.
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Affiliation(s)
- Timothy P Newsome
- Cell Motility Laboratory, Room 529, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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191
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Prins C, Cresawn SG, Condit RC. An isatin-beta-thiosemicarbazone-resistant vaccinia virus containing a mutation in the second largest subunit of the viral RNA polymerase is defective in transcription elongation. J Biol Chem 2004; 279:44858-71. [PMID: 15294890 DOI: 10.1074/jbc.m408167200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The vaccinia virus RNA polymerase is a multi-subunit enzyme that contains eight subunits in the postreplicative form. A prior study of a virus called IBT(r90), which contains a mutation in the A24 gene encoding the RPO132 subunit of the RNA polymerase, demonstrated that the mutation results in resistance to the anti-poxvirus drug isatin-beta-thiosemicarbazone (IBT). In this study, we utilized an in vitro transcription elongation assay to determine the effect of this mutation on transcription elongation. Both wild type and IBT(r90) polymerase complexes were studied with regard to their ability to pause during elongation, their stability in a paused state, their ability to release transcripts, and their elongation rate. We have determined that the IBT(r90) complex is specifically defective in elongation compared with the WT complex, pausing longer and more frequently than the WT complex. We have built a homology model of the RPO132 subunit with the yeast pol II rpb2 subunit to propose a structural mechanism for this elongation defect.
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Affiliation(s)
- Cindy Prins
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida 32610-0266, USA
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192
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Alonso A, Narisawa S, Bogetz J, Tautz L, Hadzic R, Huynh H, Williams S, Gjörloff-Wingren A, Bremer MCD, Holsinger LJ, Millan JL, Mustelin T. VHY, a Novel Myristoylated Testis-restricted Dual Specificity Protein Phosphatase Related to VHX. J Biol Chem 2004; 279:32586-91. [PMID: 15138252 DOI: 10.1074/jbc.m403442200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The human DUSP15 gene encodes an uncharacterized 235-amino acid member of the subfamily of small dual specificity protein phosphatases related to the Vaccinia virus VH1 phosphatase. Similar to VHR-related MKPX (VHX) (DUSP22), the predicted protein has an N-terminal myristoylation recognition sequence, and we show here that both are indeed modified by the attachment of a myristate to Gly-2. In recognition of this relatedness to VHX, we refer to the DUSP15-encoded protein as VH1-related member Y (VHY). We report that VHY is expressed at high levels in the testis and barely detectable levels in the brain, spinal cord, and thyroid. A VHY-specific antiserum detected a protein with an apparent molecular mass of 26 kDa, and histochemical analysis showed that VHY was readily detectable in pachytene spermatocytes (midstage of meiotic division I) and round spermatids and weakly in Leydig cells (somatic cells outside of the seminiferous tubules). When expressed in 293T or NIH-3T3 cells, VHY was concentrated at the plasma membrane with some staining of vesicular structures in the Golgi region. Mutation of the myristoylation site Gly-2 abrogated membrane location. Finally, we demonstrate that VHY is an active phosphatase in vitro. We conclude that VHY is a new member of a subgroup of myristoylated VH1-like small dual specificity phosphatases.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Binding Sites
- Blotting, Northern
- Blotting, Southern
- Cell Line
- Cell Line, Tumor
- Cell Membrane/metabolism
- Cytoplasm/metabolism
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Dual-Specificity Phosphatases
- Embryo, Mammalian/metabolism
- Fibroblasts/metabolism
- Glutathione Transferase/metabolism
- Glycine/chemistry
- Golgi Apparatus/metabolism
- Humans
- Immunoblotting
- Immunohistochemistry
- JNK Mitogen-Activated Protein Kinases
- MAP Kinase Kinase 4
- Male
- Mice
- Mice, Inbred C57BL
- Microscopy, Confocal
- Microscopy, Fluorescence
- Mitogen-Activated Protein Kinase Kinases/metabolism
- Mitogen-Activated Protein Kinase Phosphatases
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Myristic Acids/chemistry
- NIH 3T3 Cells
- Nitrophenols/chemistry
- Organophosphorus Compounds/chemistry
- Phosphoprotein Phosphatases/chemistry
- Phosphoric Monoester Hydrolases/metabolism
- Protein Structure, Tertiary
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/metabolism
- RNA, Messenger/metabolism
- Repressor Proteins/chemistry
- Repressor Proteins/metabolism
- Sequence Homology, Amino Acid
- Spermatids/metabolism
- Testis/metabolism
- Transfection
- Vaccinia virus/metabolism
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Affiliation(s)
- Andres Alonso
- Program of Signal Transduction, Cancer Research Center, The Burnham Institute, La Jolla, California 92037, USA
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193
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Abstract
Certain core and membrane proteins of vaccinia virus undergo proteolytic cleavage at consensus AG/X sites. The processing of core proteins is coupled to morphogenesis and is inhibited by the drug rifampin, whereas processing of the A17 membrane protein occurs at an earlier stage of assembly and is unaffected by the drug. A temperature-sensitive mutant with a lesion in the I7L gene exhibits blocks in morphogenesis and in cleavage of core proteins. We found that the mutant also failed to cleave the A17 membrane protein. To further investigate the role of the putative I7 protease, we constructed a conditional lethal mutant in which the I7L gene was regulated by the Escherichia coli lac repressor. In the absence of an inducer, the synthesis of I7 was repressed, proteolytic processing of the A17 membrane protein and the L4 core protein was inhibited, and virus morphogenesis was blocked. Under these conditions, expression of the wild-type I7 protein in trans restored protein processing. In contrast, rescue did not occur when the putative protease active site residue histidine 241 or cysteine 328 of I7 was converted to alanine. The mutation of an authentic AG/A and an alternative AG/S motif of L4 prevented substrate cleavage. Similarly, when AG/X sites of A17 were mutated, I7-induced cleavages at the N and C termini failed to occur. In conclusion, we provide evidence that I7 is a viral protease that is required for AG/X-specific cleavages of viral membrane and core proteins, which occur at early and late stages of virus assembly, respectively.
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Affiliation(s)
- Camilo Ansarah-Sobrinho
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Center Drive, MSC 0445, Bethesda, MD 20892-0445, USA
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194
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Kwak H, Mustafa W, Speirs K, Abdool AJ, Paterson Y, Isaacs SN. Improved protection conferred by vaccination with a recombinant vaccinia virus that incorporates a foreign antigen into the extracellular enveloped virion. Virology 2004; 322:337-48. [PMID: 15110531 DOI: 10.1016/j.virol.2004.02.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Revised: 08/18/2003] [Accepted: 02/16/2004] [Indexed: 10/26/2022]
Abstract
Recombinant poxviruses have shown promise as vaccine vectors. We hypothesized that improved cellular immune responses could be developed to a foreign antigen by incorporating it as part of the extracellular enveloped virion (EEV). We therefore constructed a recombinant vaccinia virus that replaced the cytoplasmic domain of the B5R protein with a test antigen, HIV-1 Gag. Mice immunized with the virus expressing Gag fused to B5R had significantly better primary CD4 T-cell responses than recombinant virus expressing HIV-Gag from the TK-locus. The CD8 T-cell responses were less different between the two groups. Importantly, although we saw differences in the immune response to the test antigen, the vaccinia virus-specific immune responses were similar with both constructs. When groups of vaccinated mice were challenged 30 days later with a recombinant Listeria monocytogenes that expresses HIV-Gag, mice inoculated with the virus that expresses the B5R-Gag fusion protein had lower colony counts of Listeria in the liver and spleen than mice vaccinated with the standard recombinant. Thus, vaccinia virus expressing foreign antigen incorporated into EEV may be a better vaccine strategy than standard recombinant vaccinia virus.
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Affiliation(s)
- Heesun Kwak
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6073, USA
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195
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Kim TW, Lee JH, Hung CF, Peng S, Roden R, Wang MC, Viscidi R, Tsai YC, He L, Chen PJ, Boyd DAK, Wu TC. Generation and characterization of DNA vaccines targeting the nucleocapsid protein of severe acute respiratory syndrome coronavirus. J Virol 2004; 78:4638-45. [PMID: 15078946 PMCID: PMC387705 DOI: 10.1128/jvi.78.9.4638-4645.2004] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Severe acute respiratory syndrome (SARS) is a serious threat to public health and the economy on a global scale. The SARS coronavirus (SARS-CoV) has been identified as the etiological agent for SARS. Thus, vaccination against SARS-CoV may represent an effective approach to controlling SARS. DNA vaccines are an attractive approach for SARS vaccine development, as they offer many advantages over conventional vaccines, including stability, simplicity, and safety. Our investigators have previously shown that DNA vaccination with antigen linked to calreticulin (CRT) dramatically enhances major histocompatibility complex class I presentation of linked antigen to CD8(+) T cells. In this study, we have employed this CRT-based enhancement strategy to create effective DNA vaccines using SARS-CoV nucleocapsid (N) protein as a target antigen. Vaccination with naked CRT/N DNA generated the most potent N-specific humoral and T-cell-mediated immune responses in vaccinated C57BL/6 mice among all of the DNA constructs tested. Furthermore, mice vaccinated with CRT/N DNA were capable of significantly reducing the titer of challenging vaccinia virus expressing the N protein of the SARS virus. These results show that a DNA vaccine encoding CRT linked to a SARS-CoV antigen is capable of generating strong N-specific humoral and cellular immunity and may potentially be useful for control of infection with SARS-CoV.
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Affiliation(s)
- Tae Woo Kim
- Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
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196
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Langland JO, Kao P, Jacobs BL. Regulation of IL-2 gene expression and nuclear factor-90 translocation in vaccinia virus-infected cells. J Interferon Cytokine Res 2004; 23:489-500. [PMID: 14565858 DOI: 10.1089/10799900360708614] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nuclear factor-90 (NF-90) has been described as a regulatory subunit of a complex containing DNA-dependent protein kinase (DNA-PK), Ku, and NF-45, which are capable of binding the interleukin-2 (IL-2) enhancer region and stimulating IL-2 gene expression. Vaccinia virus (VV) infection of Jurkat cells induced a nuclear factor that bound specifically to the IL-2 promoter sequence and led to the expression of the IL-2 transcript. Induction of this IL-2 promoter binding factor occurred concomitantly with the induction of NF-90 and translocation of NF-90 to the nucleus. Electrophoretic mobility supershift analysis using specific anti-NF-90 serum suggested the presence of NF-90 in the IL-2 promoter binding complex. As NF-90 can bind to double-stranded RNA (dsRNA) and be phosphorylated by the dsRNA-dependent protein kinase, PKR, we investigated whether accumulation of dsRNA in VV-infected cells could regulate IL-2 gene expression. Infection of Jurkat cells with a VV mutant that produces free dsRNA led to similar levels of induced NF-90 within the cell, but the protein remained localized within the cytosol. This mutant did not lead to the accumulation of an IL-2 promoter binding complex or to the synthesis of IL-2 mRNA. Other VV mutants that produced excess dsRNA also inhibited protein binding to the IL-2 enhancer, suggesting that the presence of viral dsRNA has a role in retaining NF-90 in the cytosol and regulating IL-2 gene expression.
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Affiliation(s)
- Jeffrey O Langland
- Department of Microbiology, Arizona State University, Tempe, AZ 85287-2701, USA
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197
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Hu Y, Riesland L, Paterson AJ, Kudlow JE. Phosphorylation of mouse glutamine-fructose-6-phosphate amidotransferase 2 (GFAT2) by cAMP-dependent protein kinase increases the enzyme activity. J Biol Chem 2004; 279:29988-93. [PMID: 15133036 DOI: 10.1074/jbc.m401547200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A protein encoded by a new gene with approximately 75% homology to glutamine-fructose-6-phosphate amidotransferase (GFAT) was termed GFAT2 on the basis of this similarity. The mouse GFAT2 cDNA was cloned, and the protein was expressed with either an N-terminal glutathione S-transferase or His tag. The purified protein expressed in mammalian cells had GFAT activity. The Km values for the two substrates of reaction, fructose 6-phosphate and glutamine, were determined to be 0.8 mm for fructose 6-phosphate and 1.2 mm for glutamine, which are within the ranges determined for GFAT1. The protein sequence around the serine 202 of GFAT2 was conserved to the serine 205 of GFAT1, whereas the serine at 235 in GFAT1 was not present in GFAT2. Previously we showed that phosphorylation of serine 205 in GFAT1 by the catalytic subunit of cAMP-dependent protein kinase (PKA) inhibits its activity. Like GFAT1, GFAT2 was phosphorylated by PKA, but GFAT2 activity increased approximately 2.2-fold by this modification. When serine 202 of GFAT2 was mutated to an alanine, the enzyme not only became resistant to phosphorylation, but also the increase in activity in response to PKA also was blocked. These results indicated that the phosphorylation of serine 202 was necessary and sufficient for these alterations by PKA. GFAT2 was modestly inhibited (15%) by UDP-GlcNAc but not through detectable O-glycosylation. GFAT2 is, therefore, an isoenzyme of GFAT1, but its regulation by cAMP is the opposite, allowing differential regulation of the hexosamine pathway in specialized tissues.
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Affiliation(s)
- Yong Hu
- Department of Cell Biology, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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198
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D'Costa SM, Antczak JB, Pickup DJ, Condit RC. Post-transcription cleavage generates the 3' end of F17R transcripts in vaccinia virus. Virology 2004; 319:1-11. [PMID: 14967483 DOI: 10.1016/j.virol.2003.09.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Revised: 09/16/2003] [Accepted: 09/25/2003] [Indexed: 10/26/2022]
Abstract
Most vaccinia virus intermediate and late mRNAs possess 3' ends that are extremely heterogeneous in sequence. However, late mRNAs encoding the cowpox A-type inclusion protein (ATI), the second largest subunit of the RNA polymerase, and the late telomeric transcripts possess homogeneous 3' ends. In the case of the ATI mRNA, it has been shown that the homogeneous 3' end is generated by a post-transcriptional endoribonucleolytic cleavage event. We have determined that the F17R gene also produces homogeneous transcripts generated by a post-transcriptional cleavage event. Mapping of in vivo mRNA shows that the major 3' end of the F17R transcript maps 1262 nt downstream of the F17R translational start site. In vitro transcripts spanning the in vivo 3' end are cleaved in an in vitro reaction using extracts from virus infected cells, and the site of cleavage is the same both in vivo and in vitro. Cleavage is not observed using extract from cells infected in the presence of hydroxyurea; therefore, the cleavage factor is either virus-coded or virus-induced during the post-replicative phase of virus replication. The cis-acting sequence responsible for cleavage is orientation specific and the factor responsible for cleavage activity has biochemical properties similar to the factor required for cleavage of ATI transcripts. Partially purified cleavage factor generates cleavage products of expected size when either the ATI or F17R substrates are used in vitro, strongly suggesting that cleavage of both transcripts is mediated by the same factor.
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Affiliation(s)
- Susan M D'Costa
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610-0266, USA.
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Senkevich TG, Ward BM, Moss B. Vaccinia virus A28L gene encodes an essential protein component of the virion membrane with intramolecular disulfide bonds formed by the viral cytoplasmic redox pathway. J Virol 2004; 78:2348-56. [PMID: 14963131 PMCID: PMC369248 DOI: 10.1128/jvi.78.5.2348-2356.2004] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report the initial characterization of the product of the vaccinia virus A28L gene, which is highly conserved in all sequenced poxviruses. Our studies showed that the A28 protein is expressed at late times during the virus replication cycle and is a membrane component of the intracellular mature virion. An N-terminal hydrophobic sequence, present in all poxvirus A28 orthologs, anchors the protein in the virion surface membrane so that most of it is exposed to the cytoplasm. The cytoplasmic domain contains four conserved cysteines, which form two intramolecular disulfide bonds. Disulfide bond formation depended on the expression of three viral proteins, E10, A2.5, and G4, which together comprise a conserved cytoplasmic redox pathway. A28 is the third identified substrate of this pathway; the others are the L1 and F9 proteins. We constructed a conditional-lethal recombinant vaccinia virus with an inducible A28L gene. The recombinant virus was propagated in the presence of inducer but was unable to replicate and spread in its absence. During a single round of an abortive infection in the absence of inducer, the synthesis and processing of viral proteins, assembly of intra- and extracellular virions, and formation of actin tails occurred normally. In another paper (T. Senkevich, B. M. Ward, and B. Moss, J. Virol. 78:2357-2366, 2004), we have demonstrated that virions assembled without A28 cannot carry out a second round of infection because they are defective in cell penetration.
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Affiliation(s)
- Tatiana G Senkevich
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA
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Ward BM, Moss B. Vaccinia virus A36R membrane protein provides a direct link between intracellular enveloped virions and the microtubule motor kinesin. J Virol 2004; 78:2486-93. [PMID: 14963148 PMCID: PMC369226 DOI: 10.1128/jvi.78.5.2486-2493.2004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2003] [Accepted: 11/06/2003] [Indexed: 11/20/2022] Open
Abstract
Previous work demonstrated that intracellular enveloped vaccinia virus virions use microtubules to move from the site of membrane wrapping to the cell periphery. The mechanism and direction of intracellular virion movement predicted that viral proteins directly or indirectly interact with the microtubule motor protein kinesin. The yeast two-hybrid assay was used to test for interactions between the light chain of kinesin and the cytoplasmic tails from five viral envelope proteins. We found that the N-terminal tetratricopeptide repeat region of the kinesin light chain (KLC-TPR) interacted with the cytoplasmic tail of the viral A36R protein. A series of C- and N-terminal truncations of A36R further defined a region from residues 81 to 111 that was sufficient for interaction with KLC-TPR. Interactions were confirmed by using pull-down assays with purified glutathione S-transferase (GST)-A36R and (35)S-labeled KLC-TPR. The defined region on A36R for interaction with kinesin overlaps the recently defined region (residues 91 to 111) for interaction with the A33R envelope protein. The yeast three-hybrid system was used to demonstrate that expression of A33R interrupted the interaction between A36R and KLC-TPR, indicating that the binding of A36R is mutually exclusive to either A33R or kinesin. Pull-down assays with purified GST-A36R and (35)S-labeled KLC-TPR in the presence of competing A33R corroborated these findings. Collectively, these results demonstrated that the viral A36R protein interacts directly with the microtubule motor protein kinesin and that the viral protein A33R may regulate this interaction.
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Affiliation(s)
- Brian M Ward
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA
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