scholarly journals Recovery of Paramyxovirus Simian Virus 5 with a V Protein Lacking the Conserved Cysteine-rich Domain: The Multifunctional V Protein Blocks both Interferon-β Induction and Interferon Signaling

Virology ◽  
2002 ◽  
Vol 303 (1) ◽  
pp. 15-32 ◽  
Author(s):  
Biao He ◽  
Reay G. Paterson ◽  
Nicola Stock ◽  
Joan E. Durbin ◽  
Russell K. Durbin ◽  
...  
2002 ◽  
Vol 76 (22) ◽  
pp. 11379-11386 ◽  
Author(s):  
J. Andrejeva ◽  
E. Poole ◽  
D. F. Young ◽  
S. Goodbourn ◽  
R. E. Randall

ABSTRACT The V protein of simian virus 5 (SV5) blocks interferon signaling by targeting STAT1 for proteasome-mediated degradation. Here we present three main pieces of evidence which demonstrate that the p127 subunit (DDB1) of the UV damage-specific DNA binding protein (DDB) plays a central role in this degradation process. First, the V protein of an SV5 mutant which fails to target STAT1 for degradation does not bind DDB1. Second, mutations in the N and C termini of V which abolish the binding of V to DDB1 also prevent V from blocking interferon (IFN) signaling. Third, treatment of HeLa/SV5-V cells, which constitutively express the V protein of SV5 and thus lack STAT1, with short interfering RNAs specific for DDB1 resulted in a reduction in DDB1 levels with a concomitant increase in STAT1 levels and a restoration of IFN signaling. Furthermore, STAT1 is degraded in GM02415 (2RO) cells, which have a mutation in DDB2 (the p48 subunit of DDB) which abolishes its ability to interact with DDB1, thereby demonstrating that the role of DDB1 in STAT1 degradation is independent of its association with DDB2. Evidence is also presented which demonstrates that STAT2 is required for the degradation of STAT1 by SV5. These results suggest that DDB1, STAT1, STAT2, and V may form part of a large multiprotein complex which leads to the targeted degradation of STAT1 by the proteasome.


2003 ◽  
Vol 77 (11) ◽  
pp. 6274-6283 ◽  
Author(s):  
Olivier Leupin ◽  
Séverine Bontron ◽  
Michel Strubin

ABSTRACT The UV-damaged DNA-binding activity protein (UV-DDB) consists of two subunits, DDB1 and DDB2, and functions in DNA repair and cell cycle regulation. The DDB1 subunit is a target for the hepatitis B virus X protein (HBx). Binding of HBx to DDB1 interferes with cell growth and viability in culture and has been implicated in the establishment of viral infection. DDB1 also interacts with the V proteins encoded by several paramyxoviruses including simian virus 5 (SV5), which prevent interferon signaling by targeting either STAT1 or STAT2 proteins for proteolysis. The role of V binding to DDB1, however, remains unclear. Here we show that the V protein of SV5 (SV5-V) and HBx exhibit strikingly similar DDB1 binding properties. Thus, SV5-V and HBx bind to DDB1 in a mutually exclusive manner, and SV5-V shares with HBx the ability to enhance the steady-state levels of DDB1 and to inhibit its association with DDB2. Yet only HBx induces cell death, and SV5-V can prevent HBx from doing so by blocking its interaction with DDB1. Binding of SV5-V to DDB1 may serve another function, since SV5-V shows a decreased ability to induce STAT1 degradation in cells expressing reduced amounts of DDB1. These findings demonstrate that HBx performs a unique function through its association with DDB1 for which SV5-V cannot substitute and suggest that SV5-V and HBx have evolved to bind DDB1 to achieve distinct functions, both by a mechanism that does not involve DDB2.


2000 ◽  
Vol 74 (19) ◽  
pp. 9152-9166 ◽  
Author(s):  
Grace Y. Lin ◽  
Robert A. Lamb

ABSTRACT Infection of cells by many viruses affects the cell division cycle of the host cell to favor viral replication. We examined the ability of the paramyxovirus simian parainfluenza virus 5 (SV5) to affect cell cycle progression, and we found that SV5 slows the rate of proliferation of HeLa T4 cells. The SV5-infected cells had a delayed transition from G1 to S phase and prolonged progression through S phase, and some of the infected cells were arrested in G2 or M phase. The levels of p53 and p21CIP1were not increased in SV5-infected cells compared to mock-infected cells, suggesting that the changes in the cell cycle occur through a p53-independent mechanism. However, the phosphorylation of the retinoblastoma protein (pRB) was delayed and prolonged in SV5-infected cells. The changes in the cell cycle were also observed in cells expressing the SV5 V protein but not in the cells expressing the SV5 P protein or the V protein lacking its unique C terminus (VΔC). The unique C terminus of the V protein of SV5 was shown previously to interact with DDB1, which is the 127-kDa subunit of the multifunctional damage-specific DNA-binding protein (DDB) heterodimer. The coexpression of DDB1 with V can partially restore the changes in the cell cycle caused by expression of the V protein.


2001 ◽  
Vol 75 (7) ◽  
pp. 3363-3370 ◽  
Author(s):  
D. F. Young ◽  
N. Chatziandreou ◽  
B. He ◽  
S. Goodbourn ◽  
R. A. Lamb ◽  
...  

ABSTRACT Previous work has demonstrated that the V protein of simian virus 5 (SV5) targets STAT1 for proteasome-mediated degradation (thereby blocking interferon [IFN] signaling) in human but not in murine cells. In murine BF cells, SV5 establishes a low-grade persistent infection in which the virus fluxes between active and repressed states in response to local production of IFN. Upon passage of persistently infected BF cells, virus mutants were selected that were better able to replicate in murine cells than the parental W3 strain of SV5 (wild type [wt]). Viruses with mutations in the Pk region of the N-terminal domain of the V protein came to predominate the population of viruses carried in the persistently infected cell cultures. One of these mutant viruses, termed SV5 mci-2, was isolated. Sequence analysis of the V/P gene of SV5 mci-2 revealed two nucleotide differences compared to wt SV5, only one of which resulted in an amino acid substitution (asparagine [N], residue 100, to aspartic acid [D]) in V. Unlike the protein of wt SV5, the V protein of SV5 mci-2 blocked IFN signaling in murine cells. Since the SV5 mci-2 virus had additional mutations in genes other than the V/P gene, a recombinant virus (termed rSV5-V/P N100D) was constructed that contained this substitution alone within the wt SV5 backbone to evaluate what effect the asparagine-to-aspartic-acid substitution in V had on the virus phenotype. In contrast to wt SV5, rSV5-V/P N100D blocked IFN signaling in murine cells. Furthermore, rSV5-V/P N100D virus protein synthesis in BF cells continued for significantly longer periods than that for wt SV5. However, even in cells infected with rSV5-V/P N100D, there was a late, but significant, inhibition in virus protein synthesis. Nevertheless, there was an increase in virus yield from BF cells infected with rSV5-V/P N100D compared to wt SV5, demonstrating a clear selective advantage to SV5 in being able to block IFN signaling in these cells.


2000 ◽  
Vol 74 (17) ◽  
pp. 7834-7841 ◽  
Author(s):  
Cheng Huang ◽  
Katsuhiro Kiyotani ◽  
Yutaka Fujii ◽  
Noriko Fukuhara ◽  
Atsushi Kato ◽  
...  

ABSTRACT The V protein of Sendai virus (SeV) is nonessential to virus replication in cell culture but indispensable to viral pathogenicity in mice. The highly conserved cysteine-rich zinc finger-like domain in its carboxyl terminus is believed to be responsible for this viral pathogenicity. In the present study, we showed that the cysteine-rich domain of the SeV V protein could actually bind zinc by using glutathione-S-transferase fusion proteins. When the seven conserved cysteine residues at positions 337, 341, 353, 355, 358, 362, and 365 were replaced individually, the zinc-binding capacities of the mutant proteins were greatly impaired, ranging from 22 to 68% of that of the wild type. We then recovered two mutant SeVs from cDNA, which have V-C341S and V-C365R mutations and represent maximal and minimal zinc-binding capacities among the corresponding mutant fusion proteins, respectively. The mutant viruses showed viral protein synthesis and growth patterns similar to those of wild-type SeV in cultured cells. However, the mutant viruses were strongly attenuated in mice in a way similar to that of SeV VΔC, which has a truncated V protein lacking the cysteine-rich domain, by exhibiting earlier viral clearance from the mouse lung and less virulence to mice. We therefore conclude that the zinc-binding capacity of the V protein is involved in viral pathogenesis.


2002 ◽  
Vol 76 (5) ◽  
pp. 2159-2167 ◽  
Author(s):  
J. Andrejeva ◽  
D. F. Young ◽  
S. Goodbourn ◽  
R. E. Randall

ABSTRACT Human cell lines were isolated that express the V protein of either simian virus 5 (SV5) or human parainfluenza virus type 2 (hPIV2); the cell lines were termed 2f/SV5-V and 2f/PIV2-V, respectively. STAT1 was not detectable in 2f/SV5-V cells, and the cells failed to signal in response to either alpha/beta interferons (IFN-α and IFN-β, or IFN-α/β) or gamma interferon (IFN-γ). In contrast, STAT2 was absent from 2f/PIV2-V cells, and IFN-α/β but not IFN-γ signaling was blocked in these cells. Treatment of both 2f/SV5-V and 2f/PIV2-V cells with a proteasome inhibitor allowed the respective STAT levels to accumulate at rates similar to those seen in 2fTGH cells, indicating that the V proteins target the STATs for proteasomal degradation. Infection with SV5 can lead to a complete loss of both phosphorylated and nonphosphorylated forms of STAT1 by 6 h postinfection. Since the turnover of STAT1 in uninfected cells is longer than 24 h, we conclude that degradation of STAT1 is the main mechanism by which SV5 blocks interferon (IFN) signaling. Pretreatment of 2fTGH cells with IFN-α severely inhibited both SV5 and hPIV2 protein synthesis. However, and in marked contrast, pretreatment of 2fTGH cells with IFN-γ had little obvious effect on SV5 protein synthesis but did significantly reduce the replication of hPIV2. Pretreament with IFN-α or IFN-γ did not induce an antiviral state in 2f/SV5-V cells, indicating either that the induction of an antiviral state is completely dependent on STAT signaling or that the V protein interferes with other, STAT-independent cell signaling pathways that may be induced by IFNs. Even though SV5 blocked IFN signaling, the addition of exogenous IFN-α to the culture medium of 2fTGH cells 12 h after a low-multiplicity infection with SV5 significantly reduced the subsequent cell-to-cell spread of virus. The significance of the results in terms of the strategy that these viruses have evolved to circumvent the IFN response is discussed.


Virology ◽  
2002 ◽  
Vol 303 (1) ◽  
pp. 33-46 ◽  
Author(s):  
Emma Poole ◽  
Biao He ◽  
Robert A. Lamb ◽  
Richard E. Randall ◽  
Stephen Goodbourn

1999 ◽  
Vol 73 (12) ◽  
pp. 9928-9933 ◽  
Author(s):  
L. Didcock ◽  
D. F. Young ◽  
S. Goodbourn ◽  
R. E. Randall

ABSTRACT To replicate in vivo, viruses must circumvent cellular antiviral defense mechanisms, including those induced by the interferons (IFNs). Here we demonstrate that simian virus 5 (SV5) blocks IFN signalling in human cells by inhibiting the formation of the IFN-stimulated gene factor 3 and gamma-activated factor transcription complexes that are involved in activating IFN-α/β- and IFN-γ-responsive genes, respectively. SV5 inhibits the formation of these complexes by specifically targeting STAT1, a component common to both transcription complexes, for proteasome-mediated degradation. Expression of the SV5 structural protein V, in the absence of other virus proteins, also inhibited IFN signalling and induced the degradation of STAT1. Following infection with SV5, STAT1 was degraded in the absence of virus protein synthesis and remained undetectable for up to 4 days postinfection. Furthermore, STAT1 was also degraded in IFN-pretreated cells, even though the cells were in an antiviral state. Since pretreatment of cells with IFN delayed but did not prevent virus replication and protein synthesis, these observations suggest that following infection of IFN-pretreated cells, SV5 remains viable within the cells until they eventually go out of the antiviral state.


2003 ◽  
Vol 77 (3) ◽  
pp. 2174-2181 ◽  
Author(s):  
D. F. Young ◽  
L. Andrejeva ◽  
A. Livingstone ◽  
S. Goodbourn ◽  
R. A. Lamb ◽  
...  

ABSTRACT The V protein of the paramyxovirus simian virus 5 blocks interferon (IFN) signaling by targeting STAT1 for proteasome-mediated degradation. Here we report on the isolation of human cell lines that express the V protein and can no longer respond to IFN. A variety of viruses, particularly slow-growing wild-type viruses and vaccine candidate viruses (which are attenuated due to mutations that affect virus replication, virus spread, or ability to circumvent the IFN response), form bigger plaques and grow to titers that are increased as much as 10- to 4,000-fold in these IFN-nonresponsive cells. We discuss the practical applications of using such cells in vaccine development and manufacture, virus diagnostics and isolation of newly emerging viruses, and studies on host cell tropism and pathogenesis.


2004 ◽  
Vol 78 (10) ◽  
pp. 5068-5078 ◽  
Author(s):  
Minghao Sun ◽  
Terri A. Rothermel ◽  
Laurie Shuman ◽  
Jason A. Aligo ◽  
Shibo Xu ◽  
...  

ABSTRACT The paramyxovirus family includes many well-known human and animal pathogens as well as emerging viruses such as Hendra virus and Nipah virus. The V protein of simian virus 5 (SV5), a prototype of the paramyxoviruses, contains a cysteine-rich C-terminal domain which is conserved among all paramyxovirus V proteins. The V protein can block both interferon (IFN) signaling by causing degradation of STAT1 and IFN production by blocking IRF-3 nuclear import. Previously, it was reported that recombinant SV5 lacking the C terminus of the V protein (rSV5VΔC) induces a severe cytopathic effect (CPE) in tissue culture whereas wild-type (wt) SV5 infection does not induce CPE. In this study, the nature of the CPE and the mechanism of the induction of CPE were investigated. Through the use of DNA fragmentation, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling, and propidium iodide staining assays, it was shown that rSV5VΔC induced apoptosis. Expression of wt V protein prevented apoptosis induced by rSV5VΔC, suggesting that the V protein has an antiapoptotic function. Interestingly, rSV5VΔC induced apoptosis in U3A cells (a STAT1-deficient cell line) and in the presence of neutralizing antibody against IFN, suggesting that the induction of apoptosis by rSV5VΔC was independent of IFN and IFN-signaling pathways. Apoptosis induced by rSV5VΔC was blocked by a general caspase inhibitor, Z-VAD-FMK, but not by specific inhibitors against caspases 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 13, suggesting that rSV5VΔC-induced apoptosis can occur in a caspase 12-dependent manner. Endoplasmic reticulum stress can lead to activation of caspase 12; compared to the results seen with mock and wt SV5 infection, rSV5VΔC infection induced ER stress, as demonstrated by increased expression levels of known ER stress indicators GRP 78, GRP 94, and GADD153. These data suggest that rSV5VΔC can trigger cell death by inducing ER stress.


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