微丝错构介导的小金蝠蛾细胞免疫耐受反应

Cellular immunity tolerance of Thitarodes xiaojinensis induced by an abnormal microfilament assembly

【目的】小金蝠蛾Thitarodes xiaojinensis细胞免疫反应耐受冬虫夏草菌Ophiocordyceps sinensis的侵染,是非常独特的宿主昆虫与病原真菌免疫互作的研究模型。本研究旨在明确冬虫夏草菌侵染对小金蝠蛾血细胞形态以及伪足形成相关基因表达的影响,初步解析宿主细胞免疫反应耐受该真菌侵染的机制。【方法】利用扫描电子显微镜技术和激光共聚焦荧光显微技术,分别观察并比较健康小金蝠蛾和感染冬虫夏草菌的小金蝠蛾血细胞的形态差异。通过实时定量PCR技术检测冬虫夏草菌感染前后,宿主血细胞微丝组装相关基因的表达变化。【结果】冬虫夏草菌侵染后,小金蝠蛾血细胞丝状伪足和片状伪足的形成受到抑制;促微丝组装基因DRF显著下调表达(P<0.01),抑制微丝组装基因thymosin显著上调表达(P<0.01)。【结论】冬虫夏草菌侵染后,小金蝠蛾血细胞微丝的组装受到阻碍,导致血细胞伪足的形成受到抑制,进而使得宿主细胞免疫反应耐受该真菌的侵染。

[Objectives] The cellular immune response of Thitarodes xiaojinensis does not prevent infection by Ophiocordyceps sinensis and therefore provides a distinct and valuable model for studying the immune interaction between host insects and entomopathogenic fungi. The aim of this study is to investigate the effects of O. sinensis infection on the morphology of T. xiaojinensis hemocytes and the transcription levels of genes related to pseudopodia formation. [Methods] A scanning electron microscope and laser scanning confocal microscope were used to observe and compare differences in hemocyte morphology between healthy and O. sinensis-infected T. xiaojinensis. Real-time quantitative PCR was used to detect transcriptional changes in genes involved in microfilament synthesis in hemocytes before, and after, infection with O. sinensis.[Results] The formation of filopodia and lamellipodia in T. xiaojinensis hemocytes was inhibited after infection by O.sinensis. Expression of the DRF gene(promoting microfilament assembly) was also significantly down-regulated(P<0.01) and thymosin(a microfilament assembly inhibitor) was significantly up-regulated(P<0.01). [Conclusion] The microfilament assembly of T. xiaojinensis hemocytes was inhibited by infection with O. sinensis, preventing formation of hemocytes’ filopodia, thereby allowing the fungus to circumvent the host cellular immunity.