Simpson D A, Condit R C
Department of Immunology and Medical Microbiology, University of Florida, Gainesville 32610-0266.
J Virol. 1994 Jun;68(6):3642-9. doi: 10.1128/JVI.68.6.3642-3649.1994.
The vaccinia virus gene A18R is essential for virus infection. The loss of A18R protein function results in unregulated transcription late during virus infection from regions of the viral genome which are normally transcriptionally quiescent. We have characterized A18R protein expression in cells infected with wild-type virus and the A18R temperature-sensitive mutant Cts23. The A18R protein is expressed during early and late phases of infection. The A18R protein expressed by Cts23 virus at permissive and nonpermissive temperatures is significantly less stable than the wild-type A18R protein. The A18R protein was identified as a virion component and localized by detergent extraction to the virion core. Virions purified from cells infected with the A18R temperature-sensitive mutants Cts4, Cts22, and Cts23 are defective in early viral transcription in vitro. The mutant transcription defect is not attributable to gross defects in virion structure or virion DNA-dependent RNA polymerase activity. We conclude that the A18R protein plays a role in viral transcription during the early phase of infection as well as during the late phase.
痘苗病毒基因A18R对病毒感染至关重要。A18R蛋白功能的丧失导致病毒感染后期从病毒基因组中通常转录静止的区域出现不受调控的转录。我们已经对感染野生型病毒和A18R温度敏感突变体Cts23的细胞中的A18R蛋白表达进行了表征。A18R蛋白在感染的早期和晚期阶段均有表达。Cts23病毒在允许温度和非允许温度下表达的A18R蛋白比野生型A18R蛋白的稳定性明显更低。A18R蛋白被鉴定为病毒粒子成分，并通过去污剂提取定位于病毒粒子核心。从感染A18R温度敏感突变体Cts4、Cts22和Cts23的细胞中纯化的病毒粒子在体外早期病毒转录方面存在缺陷。突变体转录缺陷并非归因于病毒粒子结构或病毒粒子DNA依赖性RNA聚合酶活性的严重缺陷。我们得出结论，A18R蛋白在感染的早期阶段以及晚期阶段的病毒转录中均发挥作用。
