Roles of the Picornaviral 3C Proteinase in the Viral Life Cycle and Host Cells

Sun, Di; Chen, Shun; Cheng, Anchun; Wang, Mingshu

The translation and replication of the picornaviral genome utilize the host translation machinery and the alteration and cleavage of host proteins lead to inhibition of host translation and transcription and nucleus-cytoplasm transport. 3C pro and the 3CD precursor are involved in many steps of gene expression to hijack cellular resources and to generate an optimal intracellular environment for the virus life cycle. Disrupting mRNA circularization by cleaving PABP has been observed in PV, CV and HAV. After cleavage by 3C pro , some cellular factors and their fragments, such as eIF4G, PTB and PCBP2, function in distinct manners for the host cell and virus. These observations underscore the significant roles that 3C pro plays in translation, replication, and the switch from translation to replication to guarantee viral replication. At the end of the replication cycle, the release and spread of virus are closely related to cell lysis and the formation of phosphatidylserine (PS) lipid-enriched vesicles [150] . 3C pro not only induces cell death through caspase-dependent and caspase-independent pathways but also mediates fragmentation of MAP-4 and the Golgi apparatus. These findings clearly demonstrate the various mechanisms of 3C pro that are required to subvert different processes in host cells to promote the viral life cycle.