DNA sensing-independent inhibition of herpes simplex virus 1 replication by DAI/ZBP1 (original) (raw)
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Virology, 2002
Herpes simplex virus type 1 (HSV-1) is resistant to the antiviral effects of interferon (IFN)-alpha, -beta, or -gamma. The fact that ICP0(-) mutants replicate like wild-type virus in IFN-alpha/beta receptor knockout mice (Leib et al., 1999, J. Exp. Med. 189, 663) suggested that ICP0 may serve a direct role in the resistance of HSV-1 to IFN. To test this hypothesis, the effects of IFN-alpha, -beta, and -gamma were compared against wild-type HSV-1 and an ICP0(-) mutant virus, 7134. In Vero cells, 7134 was more sensitive to inhibition by low doses of type I IFN (-alpha/beta) or type II IFN (-gamma) than vesicular stomatitis virus, a well-studied IFN-sensitive virus. At a concentration of 100 U/ml, IFN-alpha, -beta, or -gamma reduced the efficiency of 7134 plaque formation by 120-, 560-, and 45-fold, respectively. In contrast, none of the IFNs reduced wild-type HSV-1 plaque formation by more than 3-fold. Even when Vero cells were infected with 10 pfu per cell, IFN-alpha and -beta inhibited 7134 replication by over 100-fold, but inhibition by IFN-gamma decreased to less than 10-fold. While IFN-beta efficiently inhibited 7134 replication in primary mouse kidney and SK-N-SH cells, IFN-gamma did not inhibit 7134 to a comparable extent in these cells. ICP0 provided in trans from an adenovirus vector allowed 7134 to replicate efficiently in Vero cells in the presence of IFN-alpha, -beta, or -gamma. While IFN-beta or -gamma efficiently repressed the ICP0 promoter-lacZ reporter gene in 7134 (i.e., approximately 60-fold reduction in beta-galactosidase activity), ICP0 provided in trans almost completely reversed IFN-mediated repression of the lacZ gene in 7134. The results suggest that the rate of ICP0 expression in infected cells in vivo may be critical in determining whether host IFNs repress the HSV-1 genome. This concept is discussed in light of its potential relevance to the establishment of latent HSV-1 infections.
Journal of Virology, 2001
Herpes simplex virus (HSV) ICP0 can effectively activate gene expression from otherwise silent promoters contained on persisting viral genomes. However, the expression of high levels of ICP0, as from ICP4 ؊ HSV type 1 (HSV-1) vectors, results in marked toxicity. We have analyzed the results of ICP0 expressed from an E1 ؊ E4 ؊ adenovirus vector (AdS.11E4ICP0) in which ICP0 expression is controlled from the endogenous adenoviral E4 promoter. In this system, the expression level of ICP0 was reduced more than 1,000-fold relative to the level of expression from HSV-1 vectors. This low level of ICP0 did not affect cellular division or greatly perturb cellular metabolism as assessed by gene expression array analysis comparing the effects of HSV and adenovirus vector strains. However, this amount of ICP0 was sufficient to quantitatively destroy ND10 structures as measured by promyelocytic leukemia immunofluorescence. The levels of adenovirus-expressed ICP0 were sufficient to activate quiescent viral genomes in trans and promote persistent transgene expression in cis. Moreover, infection of complementing cells with AdS.11E4ICP0 promoted viral growth and resulted in a 20-fold increase in the plaquing efficiency of d109, a virus defective for all five immediate-early genes. Thus, the low level expression of ICP0 from the E1 ؊ E4 ؊ adenovirus vector may increase the utility of adenovirus vectors and also provides a means to efficiently quantify and possibly propagate HSV vectors defective in ICP0. Importantly, the results demonstrate that the activation function of ICP0 may not result from changes in cellular gene expression, but possibly as a direct consequence of an enzymatic function inherent to the protein that may involve its action at ND10 resulting in the preferential activation of viral genomes.
PLoS Pathogens, 2014
Interferon-c inducible factor 16 (IFI16) is a multifunctional nuclear protein involved in transcriptional regulation, induction of interferon-b (IFN-b), and activation of the inflammasome response. It interacts with the sugar-phosphate backbone of dsDNA and modulates viral and cellular transcription through largely undetermined mechanisms. IFI16 is a restriction factor for human cytomegalovirus (HCMV) and herpes simplex virus (HSV-1), though the mechanisms of HSV-1 restriction are not yet understood. Here, we show that IFI16 has a profound effect on HSV-1 replication in human foreskin fibroblasts, osteosarcoma cells, and breast epithelial cancer cells. IFI16 knockdown increased HSV-1 yield 6-fold and IFI16 overexpression reduced viral yield by over 5-fold. Importantly, HSV-1 gene expression, including the immediate early proteins, ICP0 and ICP4, the early proteins, ICP8 and TK, and the late proteins gB and Us11, was reduced in the presence of IFI16. Depletion of the inflammasome adaptor protein, ASC, or the IFN-inducing transcription factor, IRF-3, did not affect viral yield. ChIP studies demonstrated the presence of IFI16 bound to HSV-1 promoters in osteosarcoma (U2OS) cells and fibroblasts. Using CRISPR gene editing technology, we generated U2OS cells with permanent deletion of IFI16 protein expression. ChIP analysis of these cells and wild-type (wt) U2OS demonstrated increased association of RNA polymerase II, TATA binding protein (TBP) and Oct1 transcription factors with viral promoters in the absence of IFI16 at different times post infection. Although IFI16 did not alter the total histone occupancy at viral or cellular promoters, its absence promoted markers of active chromatin and decreased those of repressive chromatin with viral and cellular gene promoters. Collectively, these studies for the first time demonstrate that IFI16 prevents association of important transcriptional activators with wt HSV-1 promoters and suggest potential mechanisms of IFI16 restriction of wt HSV-1 replication and a direct or indirect role for IFI16 in histone modification.
Herpes Simplex Virus 1 Has Multiple Mechanisms for Blocking Virus-Induced Interferon Production
Journal of Virology, 2004
In response to viral infection, host cells elicit a number of responses, including the expression of alpha/beta interferon (IFN-alpha/beta). In these cells, IFN regulatory factor-3 (IRF-3) undergoes a sequence of posttranslational modifications that allow it to act as a potent transcriptional coactivator of specific IFN genes, including IFN-beta. We investigated the mechanisms by which herpes simplex virus 1 (HSV-1) inhibits the production of IFN-beta mediated by the IRF-3 signaling pathway. Here, we show that HSV-1 infection can block the accumulation of IFN-beta triggered by Sendai virus (SeV) infection. Our results indicate that HSV-1 infection blocks the nuclear accumulation of activated IRF-3 but does not block the initial virus-induced phosphorylation of IRF-3. The former effect was at least partly mediated by increased turnover of IRF-3 in HSV-1-infected cells. Using mutant viruses, we determined that the immediate-early protein ICP0 was necessary for the inhibition of IRF-3 nuclear accumulation. Expression of ICP0 also had the ability to reduce IFN-beta production induced by SeV infection. ICP0 has been shown previously to play a role in HSV-1 sensitivity to IFN and in the inhibition of antiviral gene production. However, we observed that an ICP0 mutant virus still retained the ability to inhibit the production of IFN-beta. These results argue that HSV-1 has multiple mechanisms to inhibit the production of IFN-beta, providing additional ways in which HSV-1 can block the IFN-mediated host response.
Transcriptional Targeting of Herpes Simplex Virus for Cell-Specific Replication
1997
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The interferon-inducible DNa-sensor protein IFI16: a key player in the antiviral response
IFI16, a member of the IFN-inducible PYHIN-200 gene family, displays multifaceted activity due to its ability to bind to various target proteins and, in turn, modulate a variety cell functions including proliferation, differentiation, apoptosis/pyroptosis, senescence, and inflammation. The last few year have seen major advances in our knowledge of IFI16 antiviral activity and its role in the immune response. Indeed, a wealth of evidence now supports a key role of IFI16 in the activation of innate immunity and viral restriction against Herpesviruses and Lentiviruses, such that the definition of IFI16 as a ‘restriction factor’ is now widely accepted. However, most viruses have developed their own unique strategy to antagonize IFI16, leading to a modification or disruption of its function. This review summarizes our current understanding of how viral replication is sensed and then inhibited by IFI16 protein and the viral strategies employed to defeat this host defense mechanism. We will focus mainly on Herpesviruses, although recent discoveries on the role of IFI16 in lentiviral infection will also be considered.
Suppression of Herpes Simplex Virus 1 in MDBK Cells via the Interferon Pathway
Journal of Virology, 2004
Herpes simplex virus (HSV) normally undergoes productive infection in culture, causing cell destruction and plaque formation. Here we characterize an unusual pattern of HSV type 1 (HSV-1) infection in MDBK cells which surprisingly results in suppression of replication, cell recovery, and maintenance of virus. Compared to Vero cells, MDBK cells supported a normal productive infection at a high multiplicity with complete cell destruction. At low multiplicity, HSV also showed an identical initial specific infectivity in the two cell types. Thereafter, the progression of infection was radically different. In contrast to the rapid plaque expansion and eventual destruction in Vero monolayers, in MDBK cells, after initial plaque formation, plaque size actually decreased and, with time, monolayers recovered. Using a green fluorescent protein (GFP)-VP16-expressing virus, we monitored infection in live individual plaques. After early stages of intense GFP-VP16 expression, expression regressed...
Frontiers in Microbiology, 2016
Although many viral particles can enter a single cell, the number of viral genomes per cell that establish infection is limited. However, mechanisms underlying this restriction were not explored in depth. For herpesviruses, one of the possible mechanisms suggested is chromatinization and silencing of the incoming genomes. To test this hypothesis, we followed infection with three herpes simplex virus 1 (HSV-1) fluorescence expressing recombinants in the presence or absence of histone deacetylases inhibitors (HDACi's). Unexpectedly, a lower number of viral genomes initiated expression in the presence of these inhibitors. This phenomenon was observed using several HDACi: Trichostatin A (TSA), Suberohydroxamic Acid, Valporic Acid, and Suberoylanilide Hydroxamic Acid. We found that HDACi presence did not change the progeny outcome from the infected cells but did alter the kinetic of the gene expression from the viral genomes. Different cell types (HFF, Vero, and U2OS), which vary in their capability to activate intrinsic and innate immunity, show a cell specific basal average number of viral genomes establishing infection. Importantly, in all cell types, treatment with TSA reduced the number of viral genomes. ND10 nuclear bodies are known to interact with the incoming herpes genomes and repress viral replication. The viral immediate early protein, ICP0, is known to disassemble the ND10 bodies and to induce degradation of some of the host proteins in these domains. HDACi treated cells expressed higher levels of some of the host ND10 proteins (promyelocytic leukemia and ATRX), which may explain the lower number of viral genomes initiating expression per cell. Corroborating this hypothesis, infection with three HSV-1 recombinants carrying a deletion in the gene coding for ICP0, show a reduction in the number of genomes being expressed in U2OS cells. We suggest that alterations in the levels of host proteins involved in intrinsic antiviral defense may result in differences in the number of genomes that initiate expression.
Journal of Virology, 2000
The d105 dominant-negative mutant form of the herpes simplex virus 1 (HSV-1) single-stranded DNA-binding protein, ICP8 (d105 ICP8), inhibits wild-type viral replication, and it blocks both viral DNA replication and late gene transcription, although to different degrees (M. Gao and D. M. Knipe, J. Virol. 65:2666–2675, 1991; Y. M. Chen and D. M. Knipe, Virology 221:281–290, 1996). We demonstrate here that this protein is also capable of preventing the formation of intranuclear prereplicative sites and replication compartments during HSV infection. We defined three patterns of ICP8 localization using indirect immunofluorescence staining of HSV-1-infected cells: large replication compartments, small compartments, and no specific intranuclear localization of ICP8. Cells that form large replication compartments replicate viral DNA and express late genes. Cells that form small replication compartments replicate viral DNA but do not express late genes, while cells without viral replication ...
Mechanisms of Host IFI16, PML, and Daxx Protein Restriction of Herpes Simplex Virus 1 Replication
Journal of Virology
The initial events after DNA virus infection involve a race between epigenetic silencing of the incoming viral DNA by host cell factors and expression of viral genes. Several host gene products, including the nuclear domain 10 (ND10) components PML (promyelocytic leukemia) and Daxx (death domain-associated protein 6), as well as IFI16 (interferon-inducible protein 16), have been shown to restrict herpes simplex virus 1 (HSV-1) replication. Whether IFI16 and ND10 components work together or separately to restrict HSV-1 replication is not known. To determine the combinatorial effects of IFI16 and ND10 proteins on viral infection, we depleted Daxx or PML in primary human foreskin fibroblasts (HFFs) in the presence or absence of IFI16. Daxx or IFI16 depletion resulted in higher ICP0 mutant viral yields, and the effects were additive. Surprisingly, small interfering RNA (siRNA) depletion of PML in the HFF cells led to decreased ICP0-null virus replication, while short hairpin RNA (shRNA)...