N-Terminal Myristoylated VP5 is Required for Penetrating Cell Membrane and Promoting Infectivity in Aquareoviruses

Nonenveloped animal viruses must disrupt the host cell membrane to initiate infection. Although myristoylated outer capsid protein is known to be responsible for membrane penetration in nonenveloped viruses, the mechanisms underlying membrane penetration to enter the host cytoplasm remain poorly understood, compared to the membrane fusion mechanisms of enveloped viruses. Therefore, we aimed to directly visualize the permeation of fluorescently labeled N-terminal myristoylated VP5 (myr-VP5N) peptides of grass carp reovirus (GCRV) and investigate the molecular mechanism of GCRV infection initiation. We found that myr-VP5N peptides quickly permeate live cell membrane in a cell type-independent manner. Moreover, pretreatment with myr-VP5N promoted the viral activity in infected cells. These results provide a foundation for further studies focused on investigated the molecular events occurring during host cell entry of aquareoviruses.