家蚕微孢子虫（Nb）能够经卵垂直传播，但其侵染家蚕卵母细胞的过程和分子机理均未被阐明。研究表明，卵黄原蛋白（Vg）是多种微生物侵染宿主卵母细胞的关键介导分子。我们研究发现，Nb表面能够结合家蚕的Vg（BmVg），并仅在蛹期卵管游离于体腔且BmVg高量表达时才能侵染卵母细胞，RNAi BmVg基因能够显著抑制Nb的侵染，而不能垂直传播的微孢子虫则不能结合BmVg和侵染卵母细胞。那么，Nb侵染卵母细胞的具体时间、路径和形态是怎样的？Nb能否利用BmVg侵染卵母细胞？Nb通过表面的什么蛋白与BmVg结合？其结合位点是什么？本项目拟通过分析Nb侵染卵母细胞的具体过程及其与BmVg的关系，分离鉴定Nb与BmVg的结合蛋白，并解析互作蛋白间的结合位点，为阐明Nb垂直传播的分子机理和抗病家蚕育种提供参考。

Microsporidian Nosema bombycis (Nb) can be vertically transmitted via transovarial infection. However, the infection process and molecular mechanism remain to be elucidated. It is reported that several microorganisms can infect oocyte by hijacking host vitellogenin (Vg). We found that N. bombycis can bind to silkworm vitellogenin (BmVg), and oocyte infection only happens when BmVg highly expressed and when ovariole burst ovary and expose into coelom, and RNAi BmVg gene significantly decreases the infection of oocyte. However, microsporidia that infect silkworm but can not be vertically transmitted have no ability to bind the BmVg and infect silkworm oocyte. Then, what is the detailed time point, pathogen morphology and pathway that Nb infect oocyte? Can Nb hijack BmVg so that infect oocyte? What surface proteins that Nb use to bind the BmVg? And what are the amino acid sites that mediate the interactions? This project intends to address the detailed process that Nb infect oocyte and its correlation with BmVg, screen and identify proteins of Nb that interact with BmVg, and illuminate the amino acid sites at which the proteins intact with each other. This project will provide important references for elucidating the molecular mechanism of Nb vertical transmission and genetic breeding of silkworm that resists pebrine disease.