Effects of Sequence Variations on Enterovirus 71 Replication

EV71 can cause not only mild diseases but also severe neurological complications in children. EV71 has been circulating in Taiwan over ten years. However, molecular mechanism of severe EV71 infection was still unclear. Through comparison of complete genome in our previous study, we have found significant sequence variations located in 5’ UTR and at position 145 of VP1 which were potentially associated with disease outcome of EV71 infection. It has been suggested that sequences of 5’ UTR can affect the efficiency of IRES-dependent translation and subsequently determine the tropism in poliovirus. Besides, the position 145 of VP1 has been reported to be an important determinant for mouse adaptation and virulence. Moreover, VP1-145 residue was also shown to be positively selected in evolution and functionally related to receptor binding specificity. From our previous study, several varied sequences of 5’ UTR were within secondary structures important for interacting with IRES trans-activating factors and the patterns of VP1-145 variations were correlated to disease outcome. In this project, we would like to investigate the roles of sequence variations in 5’ UTR and VP1-145 in EV71 replication. Therefore, the study aims of this proposal are described below. (1) To investigate the roles of 5’ UTR sequence variations in EV71 replication, we will construct the recombinant EV71 carried with different sequences in 5’ UTR. The growth rate and viral protein translation will be examined and pull-down assay will be used to identify the key host factors involved in this regulation. (2) To know if VP1-145 can determine the cell tropism and cytopathogenicity of EV71, we will also generate the EV71/VP1-145 variants to detect the cell tropism and infectivity among cell lines. (3) To understand functional roles of VP1-145 in EV71 replication, we will observe the difference of EV71/VP1-145 variants in growth curve among cells and monitor the effects of VP1-145 variation on virus entry and receptor binding affinity. These studies could help us to understand molecular mechanism of EV71 pathogenesis and also contribute to identify the potential genetic markers related to severe EV71 infection.

Project ID:PC10101-1232
External Project ID:NSC99-2314-B182-049-MY3