Unité Interactions Moléculaires Flavivirus-Hôtes, Institut Pasteur, 75724 Paris, France.
Centre for Infectious Disease Research, School of Chemistry and Molecular Biosciences, University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
Virology. 2010 Mar 30;399(1):176-185. doi: 10.1016/j.virol.2009.12.036. Epub 2010 Jan 25.
The interferon-inducible 2',5'-oligoadenylate synthetase 1b (Oas1b) protein inhibits West Nile virus (WNV) infection by preventing viral RNA (vRNA) accumulation in infected cells. Serial passage of WNV in Oas1b-expressing mouse cells selected a virus variant with improved growth capacity. Two major amino acid substitutions were identified in this Oas1b-resistant WNV variant: NS3-S365G in the ATPase/helicase domain of NS3 and 2K-V9M in the C-terminal segment of NS4A. To assess their effect on antiviral activity of Oas1b, the NS3 and 2K mutations were engineered into an infectious WNV cDNA clone. The NS3 mutation alters requirement of ATP for ATPase activity and attenuates Oas1b-mediated suppression of vRNA accumulation. However, growth of NS3-mutant virus remains impaired in Oas1b-expressing cells. Only the 2K-V9M mutation efficiently rescued viral growth by promoting vRNA replication. Thus, WNV resistance to Oas1b antiviral action could be attributed to the 2K-V9M substitution with a potential role of NS3-S365G through rescue of vRNA accumulation.
干扰素诱导的 2',5'-寡聚腺苷酸合成酶 1b（Oas1b）蛋白通过阻止感染细胞中病毒 RNA（vRNA）的积累来抑制西尼罗河病毒（WNV）感染。在表达 Oas1b 的小鼠细胞中对 WNV 进行连续传代选择出一种具有增强生长能力的病毒变异体。在这种对 Oas1b 具有抗性的 WNV 变异体中鉴定出两个主要的氨基酸取代：NS3 中的 ATP 酶/解旋酶结构域中的 NS3-S365G 和 NS4A C 末端片段中的 2K-V9M。为了评估它们对 Oas1b 抗病毒活性的影响，将 NS3 和 2K 突变引入了感染性 WNV cDNA 克隆中。NS3 突变改变了 ATP 对 ATP 酶活性的需求，并减弱了 Oas1b 介导的 vRNA 积累抑制作用。然而，NS3 突变病毒的生长在表达 Oas1b 的细胞中仍然受损。只有 2K-V9M 突变通过促进 vRNA 复制有效地挽救了病毒生长。因此，WNV 对 Oas1b 抗病毒作用的抗性可归因于 2K-V9M 取代，NS3-S365G 可能通过挽救 vRNA 积累而发挥作用。
