vaccinia virus strain Copenhagen

not annotated - annotated - LINNAEUS only

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.