Association of Vaccinia Virus Fusion Regulatory Proteins with the Multicomponent Entry/Fusion Complex

Wagenaar, Timothy R.; Moss, Bernard

doi:10.1128/jvi.00274-07

Cited by 50 publications

(75 citation statements)

References 42 publications

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“…Taken together, these results indicate that VCP and A56 interact in infected cells. Of note, Wagenaar and Moss recently used tandem affinity purification and mass spectrometry to identify proteins that interact with A56 (45). Their study identified VCP as one of many proteins that copurifies with A56, lending support to our finding that these two proteins interact.…”

Section: Vol 82 2008 Expression Of Vcp On Vaccinia Virus-infected Csupporting

confidence: 71%

Cell Surface Expression of the Vaccinia Virus Complement Control Protein Is Mediated by Interaction with the Viral A56 Protein and Protects Infected Cells from Complement Attack

Girgis

DeHaven

Fan

et al. 2008

J Virol

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The vaccinia virus (VACV) complement control protein (VCP) is the major protein secreted from VACVinfected cells. It has been reported that VCP binds to the surfaces of uninfected cells by interacting with heparan sulfate proteoglycans (HSPGs). In this study, we show that VCP is also expressed on the surfaces of infected cells and demonstrate that surface localization occurs independently of HSPGs. Since VCP does not contain a transmembrane domain, we hypothesized that VCP interacts with a membrane protein that localizes to the infected-cell surface. We show that the VACV A56 membrane protein is necessary for the cell surface expression of VCP and demonstrate that VCP and A56 interact in VACV-infected cells. Since the surface expression of VCP was abrogated by reducing agents, we examined the contribution of an unpaired cysteine residue on VCP to VCP surface expression and VCP's interaction with A56. To do this, we mutated the unpaired cysteine in VCP and generated a recombinant virus expressing the altered form of VCP. Following the infection of cells with the mutant virus, VCP was neither expressed on the cell surface nor able to interact with A56. Importantly, the cell surface expression of VCP was found to protect infected cells from complementmediated lysis. Our findings suggest a new function for VCP that may be important for poxvirus pathogenesis and impact immune responses to VACV-based vaccines.The complement system is composed of ϳ30 soluble and cell surface proteins that work in concert to protect the host from invading pathogens (reviewed in references 46 and 47). Complement can become activated by multiple pathways that converge on the formation of a C3 convertase, the proteolytic complex responsible for cleaving the central complement component, C3. Cleavage of C3 results in the production of the anaphylatoxin C3a and the opsonic fragment C3b. The generation of C3b results in the formation of a C5 convertase, the proteolytic complex responsible for cleaving C5 into the C5a anaphylatoxin and C5b. C5b, in turn, nucleates the formation of a lytic pore called the membrane attack complex.

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Section: Vol 82 2008 Expression Of Vcp On Vaccinia Virus-infected Csupporting

confidence: 71%

Cell Surface Expression of the Vaccinia Virus Complement Control Protein Is Mediated by Interaction with the Viral A56 Protein and Protects Infected Cells from Complement Attack

Girgis

DeHaven

Fan

et al. 2008

J Virol

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“…Deletion or mutation of either of these proteins results in the formation of syncytia at neutral pH (62)(63)(64)(65)(66). The finding that the A56/K2 heterodimer interacts specifically with two interacting proteins of the EFC provided a mechanism for preventing syncytium formation (7,8). Turner and Moyer (5) reported that cells infected with A56 or K2 mutants have increased susceptibility to superinfection at late times.…”

Section: Discussionmentioning

confidence: 99%

“…They concluded, mainly based on UV inactivation of virus particles, that early gene expression by the primary virus was responsible for resistance to superinfection and that early gene expression by the secondary virus was prevented. Subsequent studies provided evidence that SIE can be mediated by a heterodimer formed by the A56 and K2 proteins on the cell membrane (5, 6), which interact with a protein complex on the virus surface that is required for fusion and entry (7,8). Whether this mechanism, which was demonstrated at a late phase of virus replication, is related to the early SIE was not assessed.…”

Section: Importancementioning

confidence: 99%

“…Although A56 is expressed early in infection, K2 is a late protein, making it unlikely that the early establishment of resistance to superinfection described here could be due to the combined action of the two proteins. Nevertheless, we decided to test this possibility directly using the replicationcompetent single-deletion A56R (WR⌬A56R) and K2L (WR⌬K2L) mutant viruses as well as the double-deletion (WR⌬A56R⌬K2L) mutant virus (7). Cells were infected with the wild-type WR and deletion mutants and then superinfected with WRvFire.…”

Section: Tometry: L3mentioning

confidence: 99%

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A Novel Mode of Poxvirus Superinfection Exclusion That Prevents Fusion of the Lipid Bilayers of Viral and Cellular Membranes

Laliberte

Moss

2014

J Virol

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Superinfection exclusion is a widespread phenomenon that prevents secondary infections by closely related viruses. The vaccinia virus A56 and K2 proteins in the cell membrane can prevent superinfection by interacting with the entry-fusion complex of subsequent viruses. Here, we described another form of exclusion that is established earlier in infection and does not require the A56 or K2 protein. Cells infected with one or more infectious virions excluded hundreds of superinfecting vaccinia virus particles. A related orthopoxvirus, but neither a flavivirus nor a rhabdovirus, was also excluded, indicating selectivity. Although superinfecting vaccinia virus bound to cells, infection was inhibited at the membrane fusion step, thereby preventing core entry into the cytoplasm and early gene expression. In contrast, A56/K2 protein-mediated exclusion occurred subsequent to membrane fusion. Induction of resistance to superinfection depended on viral RNA and protein synthesis by the primary virus but did not require DNA replication. Although superinfection resistance correlated with virus-induced changes in the cytoskeleton, studies with mutant vaccinia viruses indicated that the cytoskeletal changes were not necessary for resistance to superinfection. Interferon-inducible transmembrane proteins, which can inhibit membrane fusion in other viral systems, did not prevent vaccinia virus membrane fusion, suggesting that these interferon-inducible proteins are not involved in superinfection exclusion. While the mechanism remains to be determined, the early establishment of superinfection exclusion may provide a "winnertake-all" reward to the first poxvirus particles that successfully initiate infection and prevent the entry and genome reproduction of defective or less fit particles. IMPORTANCEThe replication of a virus usually follows a defined sequence of events: attachment, entry into the cytoplasm or nucleus, gene expression, genome replication, assembly of infectious particles, and spread to other cells. Although multiple virus particles may enter a cell at the same time, mechanisms exist to prevent infection by subsequent viruses. The latter phenomenon, known as superinfection exclusion, can occur by a variety of mechanisms that are not well understood. We showed that superinfection by vaccinia virus was prevented at the membrane fusion step, which closely followed virion attachment. Thus, neither gene expression nor genome replication of the superinfecting virus occurred. Expression of early proteins by the primary virus was necessary and sufficient to induce the superinfection-resistant state. Superinfection exclusion may be beneficial to vaccinia virus by selecting particles that can infect cells rapidly, excluding defective particles and synchronizing the replication cycle.T he ability of an established virus infection to interfere with a secondary infection by a homologous virus was first described in bacteriophages and subsequently in animal and plant viruses with RNA and DNA genomes (1). The wide occurrenc...

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“…A serine protease inhibitor (SPI-3) encoded by K2 depends on the association with A56 for membrane localization (166). By direct interaction with the poxvirus EFC, the A56/K2 complex prevents virus entry and fusion and likely mediates the phenomenon of superinfection exclusion (167)(168)(169)(170). Additional viral PPI studies have shown that both A16 and G9, which are physically associated within the EFC, are required for binding to A56/K2 (170).…”

Section: Virus-virus Protein Interactionsmentioning

confidence: 99%

Poxvirus Proteomics and Virus-Host Protein Interactions

Vliet

Mohamed

Zhang

et al. 2009

Microbiol Mol Biol Rev

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SUMMARY Studies of the functional proteins encoded by the poxvirus genome provide information about the composition of the virus as well as individual virus-virus protein and virus-host protein interactions, which provides insight into viral pathogenesis and drug discovery. Widely used proteomic techniques to identify and characterize specific protein-protein interactions include yeast two-hybrid studies and coimmunoprecipitations. Recently, various mass spectrometry techniques have been employed to identify viral protein components of larger complexes. These methods, combined with structural studies, can provide new information about the putative functions of viral proteins as well as insights into virus-host interaction dynamics. For viral proteins of unknown function, identification of either viral or host binding partners provides clues about their putative function. In this review, we discuss poxvirus proteomics, including the use of proteomic methodologies to identify viral components and virus-host protein interactions. High-throughput global protein expression studies using protein chip technology as well as new methods for validating putative protein-protein interactions are also discussed.

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Association of Vaccinia Virus Fusion Regulatory Proteins with the Multicomponent Entry/Fusion Complex

Cited by 50 publications

References 42 publications

Cell Surface Expression of the Vaccinia Virus Complement Control Protein Is Mediated by Interaction with the Viral A56 Protein and Protects Infected Cells from Complement Attack

Cell Surface Expression of the Vaccinia Virus Complement Control Protein Is Mediated by Interaction with the Viral A56 Protein and Protects Infected Cells from Complement Attack

A Novel Mode of Poxvirus Superinfection Exclusion That Prevents Fusion of the Lipid Bilayers of Viral and Cellular Membranes

Poxvirus Proteomics and Virus-Host Protein Interactions

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