Interferon treatment inhibits early events in vaccinia virus gene expression in infected mice

The vaccinia virus double-stranded RNA binding protein E3 has been demonstrated to inhibit the expression of cytokines, including beta interferon (IFN-␤) and tumor necrosis factor alpha (TNF-␣). However, few details regarding the molecular mechanisms of this inhibition have been described. Using real-time PCR arrays, we found that E3 suppressed the induction of a diverse array of cytokines representing members of the IFN, interleukin (IL), TNF, and transforming growth factor cytokine families. We discovered that the factor(s) responsible for the induction of IL-6, TNF-␣, and inhibin beta A (INHBA) was associated with the early and late phases of virus infection. In contrast, the factor(s) which regulates IFN-␤ induction was associated with the late phase of replication. We have found that expression of these cytokines can be induced by transfection of cells with RNA isolated from vaccinia virus-infected cells. Moreover, we provide evidence that E3 antagonizes both PKR-dependent and PKR-independent pathways to regulate cytokine expression. PKR-dependent activation of p38 and NF-B was required for vaccinia virus-induced INHBA expression, whereas induction of TNF-␣ required only PKR-dependent NF-B activation. In contrast, induction of IL-6 and IFN-␤ was largely PKR independent. IL-6 induction is regulated by NF-B, while IFN-␤ induction is mediated by IFN-␤ promoter stimulator 1 and IFN regulatory factor 3/NF-B. Collectively, these results indicate that E3 suppresses distinct but interlinked host signaling pathways to inhibit the expression of a diverse array of cytokines.

Section: Discussionmentioning

confidence: 99%

Vaccinia Virus E3 Suppresses Expression of Diverse Cytokines through Inhibition of the PKR, NF-κB, and IRF3 Pathways

Myskiw

Arsenio

Bruggen

et al. 2009

“…In contrast, depleting Huh-7.5 cells of calcium had no effect on HCVpp or HCVcc infectivity, consistent with our observation that these cells do not form TJ-dependent paracellular barriers. Many viruses exhibit polarized routes of entry into primary and transformed epithelial cells, including vaccinia virus (37), VSV (8,20,40), human cytomegalovirus (18), Crimean-Congo hemorrhagic fever virus (12), coxsackievirus B, and adenovirus (14,15). Polarized entry can be mediated by several mechanisms, such as differential distribution of viral receptors on apical and basolateral surfaces, inaccessibility or inactivation of viral receptors, and postentry factors inhibiting viral replication.…”

Section: Vol 82 2008 Role Of Polarization In Hcv Entry 467mentioning

confidence: 99%

Effect of Cell Polarization on Hepatitis C Virus Entry

Mee

Grove

Harris

et al. 2008

104

The primary reservoir for hepatitis C virus (HCV) replication in vivo is believed to be hepatocytes within the liver. Three host cell molecules have been reported to be important entry factors for receptors for HCV: the tetraspanin CD81, scavenger receptor BI (SR-BI), and the tight-junction (TJ) protein claudin 1 (CLDN1). The recent discovery of a TJ protein as a critical coreceptor highlighted the importance of studying the effect(s) of TJ formation and cell polarization on HCV entry. The colorectal adenocarcinoma Caco-2 cell line forms polarized monolayers containing functional TJs and was found to express the CD81, SR-BI, and CLDN1 proteins. Viral receptor expression levels increased upon polarization, and CLDN1 relocalized from the apical pole of the lateral cell membrane to the lateral cell-cell junction and basolateral domains. In contrast, expression and localization of the TJ proteins ZO-1 and occludin 1 were unchanged upon polarization. HCV infected polarized and nonpolarized Caco-2 cells to comparable levels, and entry was neutralized by anti-E2 monoclonal antibodies, demonstrating glycoprotein-dependent entry. HCV pseudoparticle infection and recombinant HCV E1E2 glycoprotein interaction with polarized Caco-2 cells occurred predominantly at the apical surface. Disruption of TJs significantly increased HCV entry. These data support a model where TJs provide a physical barrier for viral access to receptors expressed on lateral and basolateral cellular domains.Hepatitis C virus (HCV) is an enveloped positive-stranded RNA virus and the sole member of the Hepacivirus genus, within the family Flaviviridae. Worldwide, approximately 170 million individuals are infected with HCV and a significant fraction of these people are at risk of developing serious progressive liver disease. The principal reservoir for viral replication is believed to be hepatocytes within the liver. The recent development of the retrovirus pseudoparticle system (HCVpp) (5, 25) and the ability of the JFH-1 strain of HCV to release infectious particles in cell culture (HCVcc) (30,45,51) have allowed studies on the mechanism of HCV entry and replication.Viruses initiate infection by attaching to molecules or receptors on the cell surface. Expression and localization of these receptors are often important determinants of a cell's susceptibility to infection and of virus tropism for particular tissues. The observation that HCVpp only infect human liver-derived cell lines in vitro suggests that liver-specific receptors contribute to defining the hepatotropism of HCV. Current evidence suggests that at least three host cell molecules are important for HCV entry in vitro, i.e., the tetraspanin CD81 (5, 25, 35), scavenger receptor class B member I (SR-BI) (5,23,26,39), and tight-junction (TJ) protein claudin 1 (CLDN1) (19). Recent data suggest that CLDN6 and CLDN9 can also function as coreceptors allowing HCV entry (33, 50). HCV glycoproteins (gps) have been reported to interact directly with CD81 and SR-BI (reviewed in reference 11). Mutagenesis...

“…IFNs play an important role in protection against infection by a large number of viruses, including VACV and other poxviruses (13,33,45,53). To evade the antiviral effects, VACV counteracts the IFN system by viral expression of a number of different factors, including soluble IFN receptors and intracellular proteins that block the activities of key IFN-induced genes (37).…”

mentioning

confidence: 99%

Removal of Vaccinia Virus Genes That Block Interferon Type I and II Pathways Improves Adaptive and Memory Responses of the HIV/AIDS Vaccine Candidate NYVAC-C in Mice

Gómez

Perdiguero

Nájera

et al. 2012

Self Cite

Poxviruses encode multiple inhibitors of the interferon (IFN) system, acting at different levels and blocking the induction of host defense mechanisms. Two viral gene products, B19 and B8, have been shown to act as decoy receptors of type I and type II IFNs, blocking the binding of IFN to its receptor. Since IFN plays a major role in innate immune responses, in this investigation we asked to what extent the viral inhibitors of the IFN system impact the capacity of poxvirus vectors to activate immune responses. This was tested in a mouse model with single and double deletion mutants of the vaccine candidate NYVAC-C, which expresses the HIV-1 Env, Gag, Pol, and Nef antigens. When deleted individually or in double, the type I (B19) and type II (B8) IFN binding proteins were not required for virus replication in cultured cells. Studies of immune responses in mice after DNA prime/NYVAC boost revealed that deletion of B8R and/or B19R genes improved the magnitude and quality of HIV-1-specific CD8 + T cell adaptive immune responses and impacted their memory phase, changing the contraction, the memory differentiation, the effect magnitude, and the functionality profile. For B cell responses, deletion of the viral gene B8R and/or B19R had no effect on antibody levels to HIV-1 Env. These findings revealed that single or double deletion of viral factors (B8 and B19) targeting the IFN pathway is a useful approach in the design of improved poxvirus-based vaccines.