Annexin II蛋白質在第一型單純疱疹病毒產生過程中所扮演之角色

Abstract

第一型人類單純疱疹病毒(Human herpes simplex virus type-1, HSV-1)在感染細胞的過程中需要胞吞、胞吐作用及許多細胞蛋白的參與。Annexin II蛋白質是Annexin蛋白質家族中的一員，主要功能與多種細胞行為有關，如細胞間質的交互作用及參與胞吞和胞吐作用等。根據先前的文獻，Annexin II會被包入HSV-1之初期病毒顆粒中，並且在細胞外之HSV-1病毒顆粒中也發現Annexin II的存在。因此本篇研究想探討宿主細胞中的Annexin II在HSV-1病毒產生過程中所扮演的角色。首先，我們利用siRNA - Annexin II降低VERO細胞株(非洲綠猴腎臟上皮細胞)中Annexin II mRNA的表現量，再感染HSV-1病毒，結果發現上清液中之HSV-1病毒活性效價也相對降低。進一步實驗證明，此現象並非由於細胞中Annexin II降解影響病毒侵入細胞所致；此外，HSV-1之後期病毒蛋白質表現量在Annexin II降解細胞中並無明顯改變，因此可以確認Annexin II表現量的下降並不會影響HSV病毒的複製過程。最後，經由分析受感染細胞上清液中病毒活性效價與細胞中病毒活性效價，發現細胞中Annexin II降解只會影響細胞上清液中病毒活性效價，而細胞內之病毒活性效價則沒有明顯改變；以此計算病毒之釋放效率顯示，HSV-1病毒從Annexin II降解之Vero細胞中釋放比例較正常Vero細胞低(12.5% v.s. 26%, P<0.01)。利用共軛焦顯微鏡觀察，在Annexin II降解之Vero細胞中，大部分病毒皆聚集在細胞核膜周圍；而在正常細胞，病毒則是散布在細胞質中。由以上實驗結果得知，細胞中Annexin II降解會導致單純疱疹病毒聚集在細胞核膜周圍，造成病毒從細胞中釋放的效率降低，其詳細的作用機制則須進一步的實驗來釐清。

The replication of human herpes simplex virus type-1 (HSV-1) involves a variety of cellular proteins and processes, such as endocytosis and exocytosis. Annexin II, a member of Annexin family, is involved in diverse cellular processes such as endocytosis, exocytosis, and cell matrix interactions. Recent studies indicated that Annexin II is incorporated into the primary HSV-1 virions in the perinuclear space and in the extracellular virus particles. In this study, we would like to define the role of Annexin II in HSV-1 virus production. First, siRNA was utilized to down-regulate Annexin II mRNA in Vero cell before HSV-1 infection. A significant reduction of supernatant virus titer in the Annexin II down-regulated cells was observed. Since the viral entry, HSV-1 late protein expression, and the intracellular virus titer were not disturbed in the Annexin II down-regulated cells, the reduction of Annexin II may directly influence the virus release. Using confocal microscopy, we observed that most HSV-1 particles localized at the perinuclear space in the Annexin II down-regulated Vero cells, while the distribution of HSV-1 particles in the untreated Vero cells was mainly in the cytoplasm. In summary, Annexin II plays a role in HSV virion release and reduction of Annexin II results in accumulation of virus particles at the perinuclear localization. Further analysis is required to elucidate the mechanism in which Annexin II is involved in HSV-1 release.