State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China.
State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, China
J Virol. 2019 Jan 17;93(3). doi: 10.1128/JVI.01923-18. Print 2019 Feb 1.
Alphabaculoviruses are lepidopteran-specific nucleopolyhedroviruses that replicate within the nucleus; however, the anterograde transport of the nucleocapsids of these viruses, which is an obligatory step for progeny virion production, is not well understood. In the present study, a unique gene with unknown function, namely, the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) gene, was found to be required for efficient nuclear egress of AcMNPV nucleocapsids. Our results indicate that is a late gene, and Ac51 protein was detectable from 24 to 72 h postinfection using an antibody raised against Ac51. Ac51 is distributed in both the cytoplasm and nuclei of infected cells. Upon deletion, budded virion (BV) production by 96 h posttransfection was reduced by approximately 1,000-fold compared with that of wild-type AcMNPV. Neither viral DNA synthesis nor viral gene expression was affected. Ac51 was demonstrated to be a nucleocapsid protein of BVs, and deletion did not interrupt nucleocapsid assembly and occlusion-derived virion (ODV) formation. However, BV production in the supernatants of transfected cells during a viral life cycle was substantially decreased when was deleted. Further analysis showed that, compared with wild-type AcMNPV, deletion decreased nucleocapsid egress, while the numbers of nucleocapsids in the nuclei were comparable. Deletion of also eliminated the virulence of AcMNPV Taken together, our results support the conclusion that plays an important role in the nuclear egress of nucleocapsids during BV formation and is essential for the virulence of AcMNPV.
α 型杆状病毒是鳞翅目特异性的核多角体病毒，在细胞核内复制；然而，这些病毒的核衣壳的正向转运，即产生子代病毒粒子的必需步骤，还没有得到很好的理解。在本研究中，发现了一个具有未知功能的独特基因，即美洲棉铃虫多角体病毒（AcMNPV）基因，该基因对于 AcMNPV 核衣壳的有效核出芽是必需的。我们的结果表明，是一个晚期基因，在感染后 24 到 72 小时可以用针对 Ac51 的抗体检测到 Ac51 蛋白。Ac51 分布在感染细胞的细胞质和细胞核中。在缺失后，与野生型 AcMNPV 相比，96 小时的芽生病毒（BV）产量减少了约 1000 倍。病毒 DNA 合成和病毒基因表达不受影响。Ac51 被证明是 BV 的核衣壳蛋白，缺失不会中断核衣壳的组装和由封闭形成的病毒粒子（ODV）的形成。然而，当缺失时，在转染细胞的上清液中 BV 的产量大大减少。进一步的分析表明，与野生型 AcMNPV 相比，缺失减少了核衣壳的出芽，而核中的核衣壳数量相当。缺失也降低了 AcMNPV 的毒力。综上所述，我们的结果支持这样的结论，即 在 BV 形成过程中，在核衣壳的核出芽中起重要作用，对于 AcMNPV 的毒力是必需的。
