昆虫杆状病毒经口感染因子P74的结构和功能

Structure and Function of the Baculovirus Per Os Infectivity Factor(PIF) P74

杆状病毒(Baculovirus)是一类具有囊膜包裹的双链环状DNA病毒,在自然界中以节肢动物(主要是昆虫)作为专一性宿主进行感染和传播。包涵体衍生型病毒是杆状病毒的一种表型,主要通过宿主经口食入引发感染。多种包涵体衍生型病毒囊膜蛋白在病毒原发感染过程中发挥作用,它们被称为经口感染因子。P74是最早被鉴定且研究最为深入的一种经口感染因子,本文从五个方面综述了国内外关于P74的研究成果。P74含有三个跨膜结构域和两个功能结构域。在病毒释放过程中,P74会分别受到包涵体内碱性蛋白酶和宿主中肠胰蛋白酶酶切,P74及其酶切产物和囊膜表面稳定复合物有微弱相互作用。作为病毒结合蛋白,P74和刷状缘囊膜中一个大小约为35kDa的蛋白存在相互作用,使得病毒结合到宿主细胞上。对P74结构和功能的深入研究将促进我们对昆虫杆状病毒原发感染详细分子机制的认识,并为农业生产病害控制提供参考。

Baculoviridae is a family of large,enveloped,double-stranded DNA viruses that mostly infect insects.Occlusion-derived virus is a baculovirus viral phenotype that induces primary infection when ingested by the insect host per os.Several occlusion-derived viral membrane proteins,called per os infectivity factors,have been shown to be essential for oral infectivity.Here,we review advances in structure and function studies of P74,which was the first PIF to be identified and has been extensively investigated.P74 contains two transmembrane domains in its hydrophobic C terminus which play a role in transmembrane anchoring,and two conserved domains which are involved in P74 function.P74is efficiently cleaved by an occlusion body endogenous alkaline protease and a host trypsin during baculovirus release and its digestion products are loosely associated with a stable complex formed by PIF1,PIF2 and PIF3.As a baculovirus attachment protein,P74 binds to a specific receptor of approximately 35 kDa in brush border membrane vesicles,facilitating the internalization of baculovirus into host cells.Knowledge of P74 will improve our understanding of baculovirus primary infection,which will support the design of nonchemical strategies to block baculovirus transmission or suppress pest populations.