Hartman Amy L, Dover Jason E, Towner Jonathan S, Nichol Stuart T
Special Pathogens Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, MS G-14, Atlanta, GA 30329, USA.
J Virol. 2006 Jul;80(13):6430-40. doi: 10.1128/JVI.00044-06.
The VP35 protein of Zaire Ebola virus is an essential component of the viral RNA polymerase complex and also functions to antagonize the cellular type I interferon (IFN) response by blocking activation of the transcription factor IRF-3. We previously mapped the IRF-3 inhibitory domain within the C terminus of VP35. In the present study, we show that mutations that disrupt the IRF-3 inhibitory function of VP35 do not disrupt viral transcription/replication, suggesting that the two functions of VP35 are separable. Second, using reverse genetics, we successfully recovered recombinant Ebola viruses containing mutations within the IRF-3 inhibitory domain. Importantly, we show that the recombinant viruses were attenuated for growth in cell culture and that they activated IRF-3 and IRF-3-inducible gene expression at levels higher than that for Ebola virus containing wild-type VP35. In the context of Ebola virus pathogenesis, VP35 may function to limit early IFN-beta production and other antiviral signals generated from cells at the primary site of infection, thereby slowing down the host's ability to curb virus replication and induce adaptive immunity.
扎伊尔埃博拉病毒的VP35蛋白是病毒RNA聚合酶复合体的重要组成部分，还通过阻断转录因子IRF-3的激活来拮抗细胞I型干扰素（IFN）反应。我们之前在VP35的C末端定位了IRF-3抑制结构域。在本研究中，我们发现破坏VP35的IRF-3抑制功能的突变不会破坏病毒的转录/复制，这表明VP35的这两种功能是可分离的。其次，利用反向遗传学，我们成功获得了在IRF-3抑制结构域内含有突变的重组埃博拉病毒。重要的是，我们发现重组病毒在细胞培养中的生长减弱，并且它们激活IRF-3和IRF-3诱导基因表达的水平高于含有野生型VP35的埃博拉病毒。在埃博拉病毒发病机制中，VP35可能起到限制早期IFN-β产生以及感染原发部位细胞产生的其他抗病毒信号的作用，从而减缓宿主抑制病毒复制和诱导适应性免疫的能力。
