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標題: 假性狂犬病毒與細胞拓樸異構酵素關係之研究
The study of Relation between Topoisomerase and Pseudorabies Virus
作者: 黃嘉鴻
Huang, Jia-Hurng
關鍵字: Pseudorabies virus
出版社: 獸醫學系
摘要: 中文摘要 假性狂犬病為一種重要的豬的傳染病。假性狂犬病毒(pseudorabies virus; PRV)為此病的病原,其基因體為線性雙股 DNA 其大小約為145 kbp。病毒粒子的大小約 150-180nm,其內部核心由DNA與蛋白質結合而成 ,包覆核心的蛋白殼由162個capsomers組成,為正二十面體結構( icosahedron ),最外圍封套( envelope )是醣蛋白與酯蛋白組成。根據 文獻記載,假性狂犬病毒跟單純疹病毒(herpes simplx virus)一樣, 在感 染細胞後都能抑制宿主細胞的DNA、RNA與蛋白質等大分子的合成。 本實驗室先前之研究發現拓樸異構酵素會參與假性狂犬病毒的DNA複製和 基因的表達。我們目前的研究更進一步發現在假性狂犬病毒感染細胞後, 第一型拓樸異構酵素的表現有增加的現象。由transfection實驗中,我們 也得知假性狂犬病毒的早期蛋白質(EP0)和立即早期基因(IE180)兩種調控 性質的蛋白質可以協同活化細胞第一型拓樸異構酵素的啟動子(promoter) 。此外,西方墨點法的結果偵測到第一型拓樸異構酵素蛋白質存在於病毒 顆粒,因此我們推測此酵素可能對病毒DNA形成高階結構有所幫助,並且 可能協助病毒立即早期基因的轉錄。綜合以上的實驗結果,我們可以得知 宿主細胞的第一型拓樸異構酵素幫助假性狂犬病毒完成複製,基因表達, 和成熟病毒顆粒的形成,使病毒得以順利完成其感染的生命週期。
Abstract Pseudorabies disease is an important infectious disease of swine, and pseudorabies virus (PRV) is the causative agent.The pseudorabies virus genome is a linear double-stranded DNA (about 145 kbp) The icosahedral capsid approximately150-180 nm in diameter contains 162 capsomeres, the tegument,and an envelopecontaining viral glycoprotein spikes on its surface.The type I DNA topoisomerase activity is required for the replication and gene expression of pseudorabies virus. PRV can inhibit the synthesis of cellular macromolecules, including DNA, RNA and protein, in PRV-infected cells. Previous results from our laboratory have demonstratedthat topoisomerase activity is required for the replication and gene expressionof pseudorabies virus. Our results shows that the expression of type Itopoisomerase was increased after PRV infection. From transient expressionon assay, the promoter of cellular topoisomerase I gene could be stimulatedby viral early protein 0 (EP0) and immediate-early protein (IE180), and these two regulatory proteins appeared to work synergistically. In addition, western blotting results show type I topoisomerase protein in viral particles.Owing to this we suggest this enzyme may help viral DNA higher structure formation and the transcription of viral immediate early gene. Taken together, the type I topoisomerase of host cells is essential for the viral DNA replication, gene expression and viral particle maturation in the PRV-infected cells.
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