白纹伊蚊体内ROS调控登革病毒感染水平的分子机制研究

Reactive Oxygen Species (ROS) are currently known to play important roles in the development of viral diseases. However, their roles in DENV infections in vector mosquitoes remain unknown. Our preliminary experiment indicated that DENV-2 infection in Aedes albopictus could induce significant production of hydrogen peroxide (H2O2), the most stable form of ROS, and H2O2 feeding of adult female Ae. albopictus significantly upregulated the mRNA expression of Hsp70 and Rel1 (a positive regulator of Toll immune pathway in mosquitoes). Previous studies indicated that the upregulation of Hsp70 could promote and the activation of Toll immune pathway could inhibit the replication of DENV-2. Therefore, we speculate that in the process of DENV-2 infection in Ae. albopictus, ROS could strictly control the levels of DENV infection through regulating the expression of Hsp70 and the activation of Toll immune pathways. To support the speculation, we will explore the impacts of the change of ROS levels on the expression of Hsp70 and the activation of Toll immune pathway, and their impacts on DENV infections, by using the techniques such as RNA-seq, RNAi and Q-RT-PCR. These results will benefit for our understanding of the role of ROS in DENV infections and providing new targets and scientific basis for designing more rational and effective measures for mosquito control and more in-depth exploring of the development of the diseases caused by DENV infections.

活性氧（ROS）在病毒性疾病的发生发展过程中承担重要角色。然而，ROS在登革病毒（DENV）感染媒介蚊虫中的作用尚不清楚。预实验中我们发现：DENV感染白纹伊蚊显著诱导了H2O2（ROS中最为稳定的一种）的产生；而H2O2饲喂显著上调了Hsp70和Toll通路正调控基因Rel1的表达。研究表明，Hsp70的上调表达能够促进DENV感染，而Toll免疫通路的激活能够抑制DENV感染。据此我们推测：在DENV感染白纹伊蚊的过程中，ROS通过诱导Hsp70的表达和Toll免疫通路的激活来严格调控病毒复制、增殖的水平。为此，我们将采用转录组测序、RNAi和荧光定量PCR等技术，探讨在白纹伊蚊体内ROS水平变化对Hsp70表达和Toll通路激活的调控及其对DENV感染的影响，从而深入了解ROS在DENV感染过程中的作用，为设计新的蚊虫控制方法提供靶点，为深入探讨DENV感染的致病机制提供新思路。

活性氧物质（Reactive Oxygen Species，ROS）在病毒性疾病的发生发展过程中承担重要角色。然而，ROS在登革病毒（DENV）感染媒介蚊虫中的作用尚不清楚。本项目旨在探讨ROS通过影响Hsp70蛋白基因的表达和免疫通路的激活调控DENV感染水平的可能机制。首先，本研究发现，DENV感染后白纹伊蚊脂肪体内ROS水平显著增加，而ROS水平的增加又能促进脂肪体和中肠内的病毒复制水平；其次，我们发现ROS能够诱导脂肪体内的免疫效应基因defensin、内质网Hsp70蛋白家族基因BiP和内质网外Hsp70蛋白家族基因Hsp70-A1的显著高表达；随后，本研究结果显示，DENV感染后脂肪体和中肠内的BiP表达均被显著上调，利用RNAi和热休克影响BiP的表达水平发现，BiP的表达对DENV复制水平具有负调控作用；最后，利用RNAi下调BiP的表达后进行的RNA-seq分析发现，BiP能够正调控免疫效应基因defensin-A和attacin-B的表达，同时对参与内质网蛋白折叠的分子伴侣尤其是细胞质内Hsp70蛋白家族的Hsp70-A1具有负调控作用，而有研究证实细胞质内的Hsp70又是DENV感染复制、增殖所必须，因此内质网BiP通过激活免疫应答和抑制胞质内Hsp70基因表达两方面抑制DENV的复制。综上所述，白纹伊蚊体内DENV感染后ROS水平的增加，一方面，通过上调内质网BiP的表达而激活抗病毒免疫应答从而抑制DENV复制，另一方面，通过上调内质网外的Hsp70基因的表达而促进病毒的复制，从而实现对DENV感染水平的动态调控。