Working with Zika and Usutu Viruses in Vitro

Usutu and Zika viruses are emerging arboviruses of significant medical and veterinary importance. These viruses have not been studied as well as other medically important arboviruses such as West Nile, dengue, or chikungunya viruses. As such, information regarding the behavior of Zika and Usutu viruses in the laboratory is dated. Usutu virus re-emerged in Austria in 2001 and has since spread throughout the European and Asian continents causing significant mortality among birds. Zika virus has recently appeared in the Americas and has exhibited unique characteristics of pathogenesis, including birth defects, and transmission. Information about the characteristics of Usutu and Zika viruses are needed to better understand the transmission, dispersal, and adaptation of these viruses in new environments. Since their initial characterization in the middle of last century, technologies and reagents have been developed that could enhance our abilities to study these pathogens. Currently, standard laboratory methods for these viruses are limited to 2-3 cell lines and many assays take several days to generate meaningful data. The goal of this study was to characterize these viruses in cell culture to provide some basic parameters to further their study. Cell lines from 17 species were permissive to both Zika and Usutu viruses. These viruses were able to replicate to significant titers in most of the cell lines tested. Moreover, cytopathic effects were observed in 8 of the cell lines tested. The data show that, unlike other flaviviruses, neither Zika nor Usutu viruses require an acidic environment to fuse with a host cell. This may provide a tool to help characterize events or components in the flavivirus fusion process. These data indicate that a variety of cell lines can be used to study Zika and Usutu viruses and may provide an updated foundation for the study of host-pathogen interactions, model development, and the development of therapeutics.\n\nAuthor SummaryUsutu and Zika viruses are arboviruses of identified in significant medical and veterinary outbreaks in recent years. Currently, standard laboratory methods for these viruses are limited to 2-3 cell lines and basic viral characterization has not been performed since the mid-20th century. Zika and Usutu viruses were characterized in cell culture. The data show that a variety of cell lines can be used to study the viruses. Neither Zika nor Usutu viruses require an acidic environment for host cell infection.