细胞骨架蛋白actin参与石斑鱼虹彩病毒SGIV释放

在病毒感染宿主细胞过程中,病毒利用宿主细胞骨架如微丝、微管等完成进入、运输和释放等过程。为分离鉴定石斑鱼虹彩病毒SGIV囊膜蛋白,实验应用去污剂溶解病毒囊膜,然后结合1-D-SDS-PAGE切胶分离和LC-MS/MS质谱鉴定两种方法进行检测,除了病毒编码的囊膜蛋白外,还发现7种宿主细胞来源的蛋白,包括细胞骨架微丝肌动蛋白actin等,由此推测这些宿主蛋白是与病毒纯化过程中共纯化获得。鉴于actin在病毒感染中发挥着重要的作用,进一步通过蛋白印迹、免疫电镜实验验证了actin与病毒共纯化,揭示actin是一种来源于宿主细胞并包装到病毒颗粒表面的宿主蛋白,且由于特异性作用黏附于病毒粒子表面,在分离病毒囊膜时与囊膜蛋白共纯化。此外,荧光显微镜观察发现,在病毒感染晚期,细胞变圆,细胞微丝actin蛋白和SGIV病毒共定位于细胞膜,提示actin与病毒释放相关。同时电镜观察也表明,病毒在感染细胞中释放时获得由宿主细胞质膜衍生而来的囊膜,由此推测actin可能在病毒释放时特异性包裹于SGIV病毒表面。研究表明,actin参与石斑鱼虹彩病毒SGIV的释放过程。

Actin filament involved in the release of SGIV from host cells

The cytoskeleton such as microfilaments and microtubules play important roles in the mechanism of viral infection, replication release and virus-host cell interactions. In this study, the Singapore grouper iridovirus (SGIV) particles were purified and the viral envelopes were separated from the viral particle by detergent dissolution. The envelope proteins were identified by 1-DE-MALDI TOF and LC-MALDI TOF workflows. Except for viral proteins, 7 host proteins were found to exist in the envelope component including actin. Thus, these host proteins were co-purified with the viral particles. Actin was proved to exist with the envelope by Western-blot. Further, it was observed that the actin proteins existed on the surface of the virus particles by immnoelectron microscopy, suggesting that host original actin is packed to viral particle when SGIV is matured and finally released from the host cell. Actin may be assembled in the viral surface when virus is budding or it is specifically adhered to the viral envelope. This makes actin co-purified with the envelope proteins. Further studies indicated that the virus-infected cell turn round and the viral particles were co-located with the microfilament on the cell surface. This suggested actin was involved in viral release. When the SGIV was released from the cell, the virus obtained the cell membrane as its envelope, which was observed by electron microscopy. It was speculated that actin was specifically packed to the surface of the viral particle when SGIV was released. Together, actin played important roles when the viruses were released from the host cells.