National Institutes of Infectious Disease and Vaccinology, National Health Research Institutes, Taiwan, Republic of China.
PLoS One. 2012;7(1):e30507. doi: 10.1371/journal.pone.0030507. Epub 2012 Jan 17.
Enterovirus (EV) 71 infection is known to cause hand-foot-and-mouth disease (HFMD) and in severe cases, induces neurological disorders culminating in fatality. An outbreak of EV71 in South East Asia in 1997 affected over 120,000 people and caused neurological disorders in a few individuals. The control of EV71 infection through public health interventions remains minimal and treatments are only symptomatic. Recently, human scavenger receptor class B, member 2 (SCARB2) has been reported to be a cellular receptor of EV71. We expressed human SCARB2 gene in NIH3T3 cells (3T3-SCARB2) to study the mechanisms of EV71 entry and infection. We demonstrated that human SCARB2 serves as a cellular receptor for EV71 entry. Disruption of expression of SCARB2 using siRNAs can interfere EV71 infection and subsequent inhibit the expression of viral capsid proteins in RD and 3T3-SCARB2 but not Vero cells. SiRNAs specific to clathrin or dynamin or chemical inhibitor of clathrin-mediated endocytosis were all capable of interfering with the entry of EV71 into 3T3-SCARB2 cells. On the other hand, caveolin specific siRNA or inhibitors of caveolae-mediated endocytosis had no effect, confirming that only clathrin-mediated pathway was involved in EV71 infection. Endocytosis of EV71 was also found to be pH-dependent requiring endosomal acidification and also required intact membrane cholesterol. In summary, the mechanism of EV71 entry through SCARB2 as the receptor for attachment, and its cellular entry is through a clathrin-mediated and pH-dependent endocytic pathway. This study on the receptor and endocytic mechanisms of EV71 infection is useful for the development of effective medications and prophylactic treatment against the enterovirus.
肠道病毒 71 型（EV71）感染已知可引起手足口病（HFMD），在严重情况下，可引起神经紊乱，最终导致死亡。1997 年，东南亚爆发的 EV71 疫情影响了超过 120,000 人，并导致少数人出现神经紊乱。通过公共卫生干预措施控制 EV71 感染的效果仍然很小，治疗方法仅为对症治疗。最近，人类清道夫受体 B 型成员 2（SCARB2）被报道为 EV71 的细胞受体。我们在 NIH3T3 细胞（3T3-SCARB2）中表达人类 SCARB2 基因，以研究 EV71 进入和感染的机制。我们证明人类 SCARB2 是 EV71 进入的细胞受体。使用 siRNA 破坏 SCARB2 的表达可以干扰 EV71 感染，并随后抑制 RD 和 3T3-SCARB2 中的病毒衣壳蛋白表达，但不能抑制 Vero 细胞中的表达。针对网格蛋白或动力蛋白的 siRNA 或网格蛋白介导的内吞作用的化学抑制剂均能干扰 EV71 进入 3T3-SCARB2 细胞。另一方面，窖蛋白特异性 siRNA 或窖蛋白介导的内吞作用抑制剂没有影响，证实只有网格蛋白介导的途径参与 EV71 感染。EV71 的内吞作用也发现是 pH 依赖性的，需要内体酸化，还需要完整的膜胆固醇。总之，EV71 通过 SCARB2 作为受体附着的进入机制，以及其细胞进入是通过网格蛋白介导和 pH 依赖性的内吞作用途径。这项关于 EV71 感染的受体和内吞作用机制的研究，对于开发针对肠道病毒的有效药物和预防治疗方法是有用的。
