MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Viruses. 2018 Nov 14;10(11):630. doi: 10.3390/v10110630.
Japanese encephalitis virus (JEV) is a mosquito-borne , the leading cause of viral-induced encephalitis. Several host molecules have been identified as the JEV attachment factor; however, the molecules involved in JEV entry remain poorly understood. In the present study, we demonstrate that TIM-1 is important for efficient infection by JEV. Firstly, three TIM-1 variants (V1, V2, and V3) were cloned from A549 cells, and we revealed that only ectopically TIM-1 V2 expression in 293T cells significantly promotes JEV attachment, entry and infection. Point mutation of phosphatidylserine (Ptdser) binding pocket in the TIM-1 IgV domain dampened JEV entry, indicating that TIM-1-mediated JEV infection is Ptdser-dependent. Furthermore, we found the cytoplasmic domain of TIM-1 is also required for enhancing JEV entry. Additionally, knock down of TIM-1 expression in A549 cells impaired JEV entry and infection, but not attachment, suggesting that additional factors exist in A549 cells that allow the virus to bind. In conclusion, our findings demonstrate that TIM-1 promotes JEV infection as an entry cofactor, and the polymorphism of TIM-1 is associated with JEV susceptibility to host cells.
日本脑炎病毒（JEV）是一种通过蚊子传播的病毒，是病毒性脑炎的主要病因。已经鉴定出几种宿主分子是 JEV 的附着因子，但 JEV 进入宿主细胞的分子机制仍知之甚少。在本研究中，我们证明 TIM-1 是 JEV 有效感染所必需的。首先，从 A549 细胞中克隆了三种 TIM-1 变体（V1、V2 和 V3），我们发现只有在 293T 细胞中异位表达 TIM-1 V2 才能显著促进 JEV 的附着、进入和感染。TIM-1 IgV 结构域中磷脂酰丝氨酸（Ptdser）结合口袋的点突变削弱了 JEV 的进入，表明 TIM-1 介导的 JEV 感染依赖于 Ptdser。此外，我们发现 TIM-1 的细胞质结构域也有助于增强 JEV 的进入。此外，在 A549 细胞中敲低 TIM-1 表达会损害 JEV 的进入和感染，但不影响附着，这表明 A549 细胞中存在允许病毒结合的其他因子。总之，我们的研究结果表明，TIM-1 作为进入辅助因子促进 JEV 感染，TIM-1 的多态性与 JEV 对宿主细胞的易感性有关。
