Centre d'études d'agents Pathogènes et Biotechnologies pour Santé - CPBS, CNRS-UMR 5236-UM1-UM2, Montpellier, France.
Infect Genet Evol. 2012 Aug;12(6):1275-81. doi: 10.1016/j.meegid.2012.02.003. Epub 2012 Feb 20.
The chikungunya virus (CHIKV) recently caused explosive outbreaks in Indian Ocean islands and India. During these episodes, the virus was mainly spread to humans through the bite of the mosquito Aedes albopictus. Concomitantly to the description of symptoms of an unexpected severity in infants and elderly patients, a viral genome microevolution has been highlighted, in particular consisting in the acquisition of an A226V mutation in the gene encoding envelope glycoprotein E1, which was later found to confer an increased fitness for A. albopictus. We previously decrypted the entry pathway used by CHIKV to infect human epithelial cells and showed that these mechanisms are modulated by the E1-A226V mutation. In this report we investigated the conditions for CHIKV entry into mosquito cells and we assessed the consequence of E1 gene mutation on these parameters.
Our main findings indicate that CHIKV infection of A. albopictus cell lines is sensitive to Bafilomycin A1 and chloroquine and to membrane cholesterol depletion. The E1-226V mutated LR-OPY1 isolate collected during the 2005 outbreak in La Réunion replicated more efficiently than the 37997 African reference strain in C6/36 cells. Moreover, the LR-OPY1 strain displayed greater membrane cholesterol dependence and was more sensitive to inhibition of endosomal pH acidification. Finally, using electron microscopy, we imaged CHIKV entry into C6/36 cells.
Our data support that CHIKV is endocyted into A. albopictus cells and requires membrane cholesterol as well as a low-pH environment for entry. These features are modulated in some extent by the A226V mutation in the E1 gene of the LR-OPY1 isolate. Altogether, our data provide information regarding the pathways used by CHIKV to infect A. albopictus cells.
基孔肯雅病毒（CHIKV）最近在印度洋岛屿和印度爆发性流行。在这些疫情中，病毒主要通过白纹伊蚊叮咬传播给人类。同时，与婴儿和老年患者出现意外严重症状的描述相一致，病毒基因组发生了微进化，特别是在编码包膜糖蛋白 E1 的基因中获得了 A226V 突变，后来发现该突变赋予了白纹伊蚊更高的适应性。我们之前解密了 CHIKV 感染人上皮细胞的进入途径，并表明这些机制受到 E1-A226V 突变的调节。在本报告中，我们研究了 CHIKV 进入蚊子细胞的条件，并评估了 E1 基因突变对这些参数的影响。
我们的主要发现表明，白纹伊蚊细胞系中 CHIKV 的感染对巴弗洛霉素 A1 和氯喹以及膜胆固醇耗竭敏感。在 2005 年留尼汪爆发期间收集的 E1-226V 突变 LR-OPY1 分离株比非洲 37997 参考株在 C6/36 细胞中更有效地复制。此外，LR-OPY1 株表现出更大的膜胆固醇依赖性，并且对抑制内体 pH 值酸化更敏感。最后，我们使用电子显微镜观察了 CHIKV 进入 C6/36 细胞的过程。
我们的数据支持 CHIKV 通过内吞作用进入白纹伊蚊细胞，并且进入需要膜胆固醇和低 pH 环境。这些特征在一定程度上受到 LR-OPY1 分离株 E1 基因中 A226V 突变的调节。总之，我们的数据提供了有关 CHIKV 感染白纹伊蚊细胞所使用途径的信息。
