膜融合介导的细胞自噬对犬瘟热病毒免疫抑制的调控机制研究

犬瘟热病毒感染犬等肉食动物会形成严重的免疫抑制，这是犬瘟热高致死率的主要原因，但其发生机制尚不清楚。自噬靶向降解病毒或促进病毒与受体作用，激活天然和适应性免疫。然而，病毒也进化出多种策略逃避、对抗或利用自噬为自身感染提供便利。前期实验结果表明，犬瘟热病毒强弱毒在Vero和Vero-dSlam细胞都快速诱导了自噬，强毒诱导了更多自噬体，但自噬底物p62的降解却被延迟。病毒是否利用未知机制抑制了自噬降解，逃逸了宿主免疫应答。因此，本项目拟以Vero、Vero-dSlam、犬巨噬细胞DH82和犬为研究对象，主要采用共聚焦、蛋白印迹和siRNA等方法，明确犬瘟热病毒强、弱毒是否诱发同样的细胞自噬，分析自噬相关基因的表达，检测IFN-α/β的表达和IFN-I信号通路的激活，找出自噬通路中的关键蛋白。旨在从细胞自噬角度探索犬瘟热病毒引起免疫抑制的分子机制。为开发新型疫苗或早期快速抗病毒制剂提供新线索。

Canine distemper virus (CDV) infects a broad range of dogs and other carnivores with severe immunosuppression, which is the mainly reason for its high mortality. However, the detailed mechanism remains unclear. Numerous studies have showed that autophagy might oppose viral invasion by targeting viral particles or viral components for degradation. It can also promote the interaction of viral constituents with receptors specialized in the activation of innate immunity pathways or facilitate the activation of anti-viral adaptive immunity. In response to such pressures, viruses have evolved various sophisticated strategies to avoid autophagic responses or to manipulate the autophagic machinery to promote their own replication. Our preliminary experimental data prove that wild-type CDV rapidly induce more autophagosomes accumulation than the attenuated CDV vaccine strain in both Vero and Vero-dSlam cells. However, the degradation of autophagy substrate p62 is delayed. We speculate whether the viruses utilize an unknown mechanism to inhibit autophagy degradation and escape the host immune response. Therefore, we intend to investigate the different expression levels of autophagy related genes, the expression levels of IFN-α/β and the activation of IFN-I signal pathway, and find out the key factor in signal pathway of autophagy by confocal microscopy, western blot and siRNA technique in Vero, Vero-dSlam, DH82 cells and in dog infected with wild-type CDV or attenuated vaccine strains, respectively. We aim to explore the molecular mechanism of immunosuppression caused by CDV from the perspective of autophagy. Our study findings will provide new clues for the development of new vaccines or early rapid antiviral products.