VV
not annotated - annotated - LINNAEUS only
20943971
Roles of vaccinia virus genes E3L and K3L and host genes PKR and RNase L during intratracheal infection of C57BL/6 mice.
The importance of the 2'-5' oligoadenylate synthetase (OAS)/RNase L and double-stranded RNA (dsRNA)-dependent protein kinase (PKR) pathways in host interferon induction resulting from virus infection in response to dsRNA has been well documented. In poxvirus infections, the interactions between the vaccinia virus (VV) genes E3L and K3L, which target RNase L and PKR, respectively, serve to prevent the induction of the dsRNA-dependent induced interferon response in cell culture. To determine the importance of these host genes in controlling VV infections, mouse single-gene knockouts of RNase L and PKR and double-knockout mice were studied following intratracheal infection with VV, VVDeltaK3L, or VVDeltaE3L. VV caused lethal disease in all mouse strains. The single-knockout animals were more susceptible than wild-type animals, while the RNase L(-/-) PKR(-/-) mice were the most susceptible. VVDeltaE3L infections of wild-type mice were asymptomatic, demonstrating that E3L plays a critical role in controlling the host immune response. RNase L(-/-) mice showed no disease, whereas 20% of the PKR(-/-) mice succumbed at a dose of 10(8) PFU. Lethal disease was routinely observed in RNase L(-/-) PKR(-/-) mice inoculated with 10(8) PFU of VVDeltaE3L, with a distinct pathology. VVDeltaK3L infections exhibited no differences in virulence among any of the mouse constructs, suggesting that PKR is not the exclusive target of K3L. Surprisingly, VVDeltaK3L did not disseminate to other tissues from the lung. Hence, the cause of death in this model is respiratory disease. These results also suggest that an unanticipated role of the K3L gene is to facilitate virus dissemination.
20980497
A vaccinia virus deletion mutant reveals the presence of additional inhibitors of NF-kappaB.
The classical nuclear factor kappa B (NF-kappaB) signaling pathway is an important regulator of inflammation and innate immunity that is activated by a wide variety of stimuli, including virus infection, tumor necrosis factor alpha (TNF-alpha), and interleukin 1Beta (IL-1Beta). Poxviruses, including vaccinia virus (VV) and ectromelia virus, encode multiple proteins that function in immune evasion. Recently, a growing number of genes encoded by poxviruses have been shown to target and disrupt the NF-kappaB signaling pathway. To determine if additional gene products that interfere with NF-kappaB signaling existed, we used a vaccinia virus deletion mutant, VV811, which is missing 55 open reading frames lacking all known inhibitors of TNF-alpha-induced NF-kappaB activation. Immunofluorescence analysis of HeLa cells treated with TNF-alpha and IL-1Beta revealed that NF-kappaB translocation to the nucleus was inhibited in VV811-infected cells. This was further confirmed through Western blotting of cytoplasmic and nuclear extracts for NF-kappaB. Additionally, VV811 infection inhibited TNF-alpha-induced IkappaBalpha degradation. In contrast to vaccinia virus strain Copenhagen (VVCop)-infected cells, VV811 infection resulted in the dramatic accumulation of phosphorylated IkappaBalpha. Correspondingly, coimmunoprecipitation assays demonstrated that the NF-kappaB-inhibitory IkappaBalpha-p65-p50 complex was intact in VV811-infected cells. Significantly, cells treated with 1-Beta-d-arabinofuranosylcytosine, an inhibitor of poxvirus late gene expression, demonstrated that an additional vaccinia virus late gene was involved in the stabilization of IkappaBalpha. Overall, this work indicates that unidentified inhibitors of NF-kappaB exist in vaccinia virus. The complex inhibition of NF-kappaB by vaccinia virus illustrates the importance of NF-kappaB activation in the antiviral response.