Investigation of Host Factors Affecting the Pathogenesis of Enterovirus 71 in Neuron and Non-Returnable Cells

Enterovirus is a genus of the Picornaviridae family. There are enteroviruses epidemics caused by various serotypes reported in Taiwan every year. Enterovirus 71 (EV71) infections typically cause hand, foot, and mouth disease or herpangina, followed by severe central nervous system complications, including aseptic meningitis, encephalitis, poliomyelitis-like paralysis, neurogenic cardiopulmonary failure, and even death in young children. EV71 infections have been reported in several countries, such as Taiwan, China, Japan, Malaysia, Singapore, Australia, the United States, and Germany. Thus far, there is no effective vaccine or antiviral drug available for the clinical treatment of EV71 infections. The ability of EV71 to induce disease depends on both viral genetics and the host environment. To address this problem, we will use EV71 as a virus model to investigate tissue tropism during viral infections. In addition to cell receptors, multiple cellular host factors are involved in regulating viral growth during the virus life cycle. The first aim of this project is (1) to determine the host factors involved in tissue tropism during EV71 infections. In the preliminary results, low viral replication rates were observed in Drosha-knocked-down human glioblastoma (SF268) cells compared with negative control (NC)-siRNA-treated SF268 cells. However, viral growth did not differ in human embryonal rhabdomyosarcoma (RD) cells treated with Drosha or NC siRNA. These data indicated that there might be specific factors involved in viral replication in Drosha- and NC siRNA-transfected SF268 cells that are absent in RD cells. We will use pull-down combining proteomics and next-generation sequencing assays to determine the potential factors and further study the detailed mechanisms of virus host interaction. We will also test other enteroviruses or plus-strand RNA viruses for comparison. The second aim is (2) to identify the cis-regulators of EV71 infections. After consulting numerous reports, we would like to investigate the significance of genomic diversity (hot spots), quasispecies tropism and the effects of multiple mutations in viral populations. We would also like to collaborate with clinical doctors and clinical virology laboratory teams to obtain additional clinical specimens for further study. Understanding the molecular mechanisms regulating viral translation and replication in neuron or non-neuron cell lines and the cellular host proteins involved will help identify novel molecular targets for the development of antiviral drugs against enteroviruses.