Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing 401331, People's Republic of China.
Department of Biochemistry, South Parks Rd, University of Oxford, Oxford OX1 3QU, United Kingdom.
Int J Biol Macromol. 2020 Dec 15;165(Pt A):1303-1311. doi: 10.1016/j.ijbiomac.2020.09.222. Epub 2020 Oct 3.
Conidial hydrophobins in fungal pathogens of plants, insects, and humans are required for fungal attachment and are associated with high virulence. They are believed to contribute to the pathogenesis of infection by preventing immune recognition. Here, we refute this generalisation offering a more nuanced analysis. We show that MacHYD3, a hydrophobin located on the conidial surface of the specialist entomopathogenic fungus Metarhizium acridum (narrow host range, kills only locusts and grasshoppers), activates specifically the humoral and cellular immunity of its own host insect, Locusta migratoria manilensis (Meyen) but not that of other non-host insects. When topically applied to the cuticle, purified MacHYD3 improved the resistance of locusts to both specialist and generalist fungal pathogens (wide host range) but had no effect on the fungal resistance of other insects, including Spodoptera frugiperda and Galleria mellonella. Hydrophobins extracted from the generalist fungal pathogens M. anisopliae and Beauveria bassiana had no effect on the resistance of locusts to fungal infection. Thus, the host locust has evolved to recognize the conidial hydrophobin of its specialist fungal pathogen, whereas conidial hydrophobins from generalist fungi are able to evade recognition. Our results distinguish the immunogenic potential of conidial hydrophobins between specialist and generalist fungi.
植物、昆虫和人类病原真菌中的分生孢子疏水性蛋白对于真菌附着是必需的，并且与高毒力相关。它们被认为通过防止免疫识别而有助于感染的发病机制。在这里，我们反驳了这种概括，提供了更细致的分析。我们表明，位于专性昆虫病原真菌绿僵菌（窄宿主范围，仅杀死蝗虫和蚱蜢）分生孢子表面的 MacHYD3 特异性激活其自身宿主昆虫，即东亚飞蝗的体液和细胞免疫，但不激活其他非宿主昆虫的免疫。当局部应用于表皮时，纯化的 MacHYD3 提高了蝗虫对专性和兼性真菌病原体（宽宿主范围）的抗性，但对其他昆虫（包括斜纹夜蛾和家蚕）的真菌抗性没有影响。从兼性真菌病原体玫烟色棒束孢和球孢白僵菌中提取的疏水性蛋白对蝗虫对真菌感染的抗性没有影响。因此，宿主蝗虫已经进化到能够识别其专性真菌病原体的分生孢子疏水性蛋白，而来自兼性真菌的分生孢子疏水性蛋白能够逃避识别。我们的结果区分了专性和兼性真菌中分生孢子疏水性蛋白的免疫原性潜力。
