JVI：中科院武漢病毒所胡志紅研究組揭示桿狀病毒口服感染因子複合物的組成及裝配機制

2019年1月2日，病毒學國家重點實驗室胡志紅研究員團隊在國際學術期刊Journal of Virology在線發表了題為Baculovirus peros Infectivity Factor Complex: Components and Assembly(《桿狀病毒口服感染因子複合物：組分和組裝》)的研究論文，研究揭示了桿狀病毒口服感染因子複合物的組成及裝配機制，為今後研究該複合物的結構和功能奠定了基礎。

桿狀病毒是一類昆蟲特異性病毒，在害蟲的生物防治和外源基因的表達等方面有重要的應用價值。桿狀病毒入侵宿主昆蟲依賴於病毒囊膜上的一系列口服感染因子(per os infectivityfactors, PIFs)，其中大部分PIF會以蛋白複合物的形式發揮功能，然而該複合物的組成及裝配機制並不清楚。

該研究對三種不同桿狀病毒PIF複合物進行了Blue native PAGE分離、質譜鑒定和Westernblot分析，揭示PIF複合物大小為500kDa，包括9種組分(PIF0-4，PIF6-9)，其中PIF9為新發現的口服感染因子。利用人工合成技術對複合物中的9個成員逐一進行了敲除，發現PIF1、2和3是核心成分，它們形成一個~230kDa的核心複合物，為完整複合物的組裝提供了平台(圖A)。通過核-質分離，在胞質中檢測到完整的PIF複合物，提出了複合物在細胞內裝配和運輸的模式圖(圖B)。

圖示：桿狀病毒PIF複合物的裝配機制

該研究系統地分析了桿狀病毒PIF複合物的組成和組裝，為今後研究該複合物的結構和功能奠定了基礎，被審稿人認為「This will be a landmark paper in the baculovirusfield」 (這將成為桿狀病毒研究領域的一個標誌性論文)。

ABSTRACT

Baculovirus entry into insect midgut cells is dependent on a multiprotein complex of per os infectivity factors (PIFs) on the envelope of occlusion derived virions (ODVs). The structure and assembly of the PIF complex is largely unknown. To reveal the complete members of the complex,a combination of blue native polyacrylamide gel electrophoresis, liquid chromatography-tandem mass spectrometry, and Western blots were conducted on three different baculoviruses. The results showed that the PIF complex is ～500-kDain size consisting of nine PIFs including a newly discovered member (PIF9). To decipher the assembly process, each pif was knockout from the Autographacalifornica multicapsid nucleopolyhedrovirus (AcMNPV) genome individually usingsynthetic baculovirus technology and the impact on PIF complex formation was investigated. Deletion of pif8 resulted in the formation of a ～400 kDasubcomplex. Deletion of pif0, 4, 6, 7, or 9 resulted in a subcomplex of ～230 kDa,but deletion of pif1, 2 or 3 abolished formation of any complex. Takentogether, a core-complex of ～230-kDa consisting of PIF1, 2 and 3 was identified. This revised the previous knowledge that the core-complex was about 170 kDa and contained PIF1 to 4. Analysis of the PIF complex in cellular fractions suggested that it isassembled in the cytoplasm before being transported to the nucleus and subsequent incorporation into the envelope of ODV. Only the full complex, and not the subcomplexes, is resistant to proteolytic attack, indicating the essentiality of correct complex assembly for oral infection.

資料來源：

1.Xi Wang, Yu Shang, ChengChen, Shurui Liu, Meng Chang, Nan Zhang, Hengrui Hu, Fenghua Zhang, Tao Zhang, Zhiying Wang, Xijia Liu, Zhe Lin, Fei Deng, Hualin Wang, Zhen Zou, Just M.Vlak, Manli Wang, Zhihong Hu.Baculovirus per os Infectivity FactorComplex: Components and Assembly.DOI: 10.1128/JVI.02053-18

2.中科院武漢病毒所病毒學國家重點實驗室：病毒學國家重點實驗室胡志紅研究組揭示桿狀病毒口服感染因子複合物的組成及裝配機制。

http://klv.whu.edu.cn/index.php/View/316.html

本期編輯：Annabella

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