虫菌体特异表面蛋白与球孢白僵菌逃避昆虫免疫识别的关系及作用机制

病原真菌通过表面组成或结构特化，逃避宿主昆虫免疫识别或攻击。然而，有关病原真菌表面结构特化与逃避昆虫免疫识别的机制，尚缺乏明晰的认识。球孢白僵菌在昆虫体腔内分化形成虫菌体，在表面特化出一层规则的“刷状”突起，推测其与隐蔽病原相关分子模式而逃避宿主免疫识别相关。课题组研究发现，虫菌体表面的突起结构主要由蛋白质组成。利用比较蛋白组学、生物信息学以及eGFP标签法，初步筛选了7个虫菌体特异的表面蛋白。该发现为揭示病原真菌逃避昆虫免疫识别的机制提供了重要线索。本项目拟采用免疫荧光等方法分析表面蛋白在虫菌体分化过程中的表达次序及空间关系，结合基因破坏和过表达等技术，探究特异表面蛋白对虫菌体分化以及表面特性和组成的影响，解析表面蛋白与白僵菌逃避昆虫免疫识别的关系及作用机制。项目的开展，有望在揭示病原真菌与昆虫的互作机制方面取得新的突破，而且研究结果将可能为改良和提升真菌生防效果提供理论依据。

Fungal pathogens could evade or avoid hemolymph immune recognition of the host insect by means of modification of cell surface and cell wall structure. However, the mechanism of fungal pathogen modifying cell surface feature to avoid immune detection of the host insect is still unclear. The entomopathogenic fungus, Beauveria bassiana, elaborate free floating cells termed hyphal bodies once penetrating hyphae reaching the hemocoel. It is demonstrated that a highly ordered outermost brush-like structure is uniquely present in the cell surface of B. bassiana hyphal bodies, which might be involved in evading the insect hemolymph immune response by masking the pathogen-associated molecular patters (PAMPs). We firstly revealed that the brush-like structure is mainly composed of proteins. And then, seven cell surface proteins specially expressed in the hyphal bodies has been screened and identified using comparative proteomic and bioinformatic methods, and by tagging the gene with eGFP. These findings suggested a valuable cue explore the mechanism of the fungal pathogen that evades the host insect hemolymph immune response. In this project, we are going to investigate formation of the cell surface proteins and position relationship of the different proteins in the cell surface of the hyphal bodies using immunofluorescene method as well as reverse transcription PCR (RT-PCR). Gene disruption and overexpression strains will be constructed to investigate effect of the cell wall surface proteins on hyphal body differentiation, cell surface feature and construction, and to characterize roles of the B. bassiana hyphal body-specific cell surface proteins in evading immune recognition of the host insect. One of our goals of the project is to expect to make a breakthrough on understanding mechanism of interaction between the fungal pathogen and host insect. Another goal is to hope to provide a theoretical basis for improvement of fungal the fungal agent using genetic engineering.