Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Proc Natl Acad Sci U S A. 2017 Jun 6;114(23):5994-5999. doi: 10.1073/pnas.1703546114. Epub 2017 May 22.
The insect gut microbiota plays crucial roles in modulating the interactions between the host and intestinal pathogens. Unlike viruses, bacteria, and parasites, which need to be ingested to cause disease, entomopathogenic fungi infect insects through the cuticle and proliferate in the hemolymph. However, interactions between the gut microbiota and entomopathogenic fungi are unknown. Here we show that the pathogenic fungus interacts with the gut microbiota to accelerate mosquito death. After topical fungal infection, mosquitoes with gut microbiota die significantly faster than mosquitoes without microbiota. Furthermore, fungal infection causes dysbiosis of mosquito gut microbiota with a significant increase in gut bacterial load and a significant decrease in bacterial diversity. In particular, the opportunistic pathogenic bacterium overgrows in the midgut and translocates to the hemocoel, which promotes fungal killing of mosquitoes. We further reveal that fungal infection down-regulates antimicrobial peptide and dual oxidase expression in the midgut. Duox down-regulation in the midgut is mediated by secretion of the toxin oosporein from Our findings reveal the important contribution of the gut microbiota in -killing activity, providing new insights into the mechanisms of fungal pathogenesis in insects.
昆虫肠道微生物群在调节宿主与肠道病原体之间的相互作用方面起着至关重要的作用。与需要摄入才能引起疾病的病毒、细菌和寄生虫不同，昆虫病原真菌通过表皮感染昆虫，并在血淋巴中增殖。然而，肠道微生物群与昆虫病原真菌之间的相互作用尚不清楚。在这里，我们表明，致病性真菌与肠道微生物群相互作用，从而加速蚊子的死亡。在局部真菌感染后，具有肠道微生物群的蚊子比没有微生物群的蚊子死亡速度明显更快。此外，真菌感染导致蚊子肠道微生物群的失调，肠道细菌负荷显著增加，细菌多样性显著降低。特别是，机会性致病细菌在中肠过度生长，并转移到血腔，这促进了真菌对蚊子的杀伤。我们进一步揭示了真菌感染下调了中肠中的抗菌肽和双氧化酶的表达。中肠中的 Duox 下调是由真菌 oosporein 毒素的分泌介导的。我们的研究结果揭示了肠道微生物群在真菌杀伤活性中的重要贡献，为昆虫真菌发病机制提供了新的见解。
