冬虫夏草菌调节宿主蝠蛾免疫反应机制的研究

冬虫夏草菌侵染蝠蛾，是非常独特的病原真菌与宿主昆虫免疫互作的研究模型。常见昆虫病原真菌的侵染，会激活宿主昆虫的包囊和黑化反应以及Toll免疫信号通路，致使宿主呈现不同程度的病征。虫草菌侵入蝠蛾血腔后，其芽孢能够在宿主体内积累至极高的浓度；在此期间，菌与虫长期“和平共处”，宿主虫体无明显病征。我们近期的研究结果表明，感染虫草菌的蝠蛾幼虫的酚氧化酶原和血细胞的包囊反应无法被激活，提示虫草菌可能分泌某些效应分子至宿主血腔中，调节宿主的黑化和包囊免疫反应进而完成侵染。本项目抓住虫草菌-蝠蛾长期互作的特点，首先利用蛋白质组学技术，明确感染虫草菌中期蝠蛾的血淋巴的组成；然后以宿主的免疫特征为指导，利用当代分子生物、生物化学技术，找到虫草菌分泌的关键效应分子并检验其功能，进而阐明虫草菌调节宿主免疫反应的分子机制。本研究将扩展人们对真菌-昆虫免疫互作的认识，并为人工培育冬虫夏草提供新的方法和思路。

Ghost moth larva infected by Ophiocordyceps sinensis provides a distinct and valuable model to study immunological interaction between entomopathogenic fungi and insects. Insects can activate encapsulation, melanization and Toll signaling pathway to fight against fungal infection that may cause visible symptoms shown on the host. Before mummifying the host, O. sinensis blastospores need to accumulate to an extremely high concentration in the larval hemocoel. During the long-term infection, O. sinensis blastospores freely distributed in the hemolymph, and the host presented no disease symptoms. Recently, we found that prophenoloxidase in the O. sinensis infected larvae were hardly activated, and the hemocytes could not encapsulate foreigners. These results suggest that O. sinensis may secrete effectors into the hemolymph to modulate melanization and encapsulation in the host. In this project, firstly we will examine the components in the hemolymph from O. sinensis infected larvae through proteome analysis. Next, the key effectors related to the fungal pathogenicity will be identified. Finally, the inhibition mechanism of O. sinensis to the host immune responses will be illustrated, after functional verification using sophisticated methods. This study will improve our understanding on the interaction between fungus and host insect, and meanwhile provide valuable information to artificial cultivation of the Chinese cordyceps.