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家蚕核型多角体病毒(BmNPV)包涵体衍生型病毒粒子(ODV)被家蚕幼虫食下后通过侵染中肠上皮细胞引发全身性感染,这个过程称为经口感染.已知有多种ODV囊膜蛋白在经口感染中发挥关键作用,被称为经口感染因子(PIF).P74作为最早被鉴定的PIF,与ODV结合中肠上皮细胞有关.为了鉴定宿主家蚕中肠细胞中与P74互作的蛋白质,构建家蚕中肠酵母文库,并以P74作为诱饵进行酵母双杂交筛选.初步筛选到7种互作候选蛋白,分别为U3小核仁核糖核蛋白IMP3、60S核糖体蛋白L5、JAB-MPN结构域蛋白、细胞质肌动蛋白A3、35 kD蛋白酶、富半胱氨酸和组氨酸蛋白1-B和真核翻译起始因子1A.免疫共沉淀实验结果表明JAB-MPN结构域蛋白和P74之间存在强烈互作,该蛋白质可能是ODV结合中肠细胞的关键宿主因子.研究结果为进一步阐明BmNPV经口感染的详细分子机制提供了新的线索.“,”After occlusion derived virus (ODV) of Bombyx mori nuclopolyhedrovirus (BmNPV) are ingested by silkworm (Bombyx mori) larvae,the primary infection occurs first in midgut epithelial cells and then in whole larval body.This process is called per os infection.Several ODV envelope proteins,called per os infectivity factors (PIFs),have been shown to be essential for oral infection.P74 is the first identified PIF and previous studies have shown that it plays a definite role in ODV binding to midgut epithelial cells.In order to identify the host factors essential for ODV attachment,cDNA library of silkworm midgut was constructed and yeast two-hybrid screening was conducted using P74 as the bait.Seven midgut proteins,namely U3 small nucleolar ribonucleoprotein protein IMP3,60S ribosomal protein L5,JAB-MPN domain protein,cytoplasmic actin A3,35 kD protease,cysteine and histidine-rich protein 1-B and eukaryotic translation initiation factor 1A,were identified as potential interacting proteins.Co-lmmunoprecipitation verification showed that JAB-MPN domain protein has a strong interaction with P74,suggesting that JAB-MPN domain protein is the essential host factor for ODV entry.In conclusion,this study provides a new clue for elucidating the molecular mechanisms of per os infection of BmNPV.