Dengue and Zika virus NS5-host protein-protein interactions modulate cellular functions

LEOPOLDO G. GEBHARD; ANDREA V. GAMARNIK; NESTOR G. IGLESIAS; GONZALEZ LOPEZ LEDESMA, MARIA MORA; FEDERICO A. DE MAIO

Encuentro; The 18th Rocky Mountain Virology Association Meeting; 2018

Dengue virus (DENV) is one of the most important human viral pathogens transmitted by insects; it belongs to the Flaviviridae family, together with other human pathogens, such as West Nile virus, Japanese encephalitis virus and Zika virus (ZIKV). The recent outbreak of ZIKV in America and its link to microcephaly put this virus at the forefront of an international research effort to understand its cellular targets and pathogenesis. Flavivirus NS5 protein plays multiple functions during infection, enabling viral replication and counteracting host antiviral responses. To investigate the interaction of NS5 with cellular components, we performed proteomic studies using tagged DENV. We identified 53 host proteins that bind or form complexes with NS5. We validated a number of these interactions and extended these studies to ZIKV NS5. Among the NS5 binders, we found core components of the host spliceosome machinery: components of the U5 snRNP particle(CD2BP2, DDX23 and EFTUD2). Interestingly, silencing of these proteins enhanced DENV viral replication. A model was proposed, in which NS5 binding to U5 snRNP proteins hijacks the splicing machinery resulting in a less restrictive environment for viral replication. We have recently observed that down-regulation of CD2BP2 slightly increased ZIKV replication, although further studies are needed. In summary, we developed a technology to investigate protein-protein interactions during viral infection that was used to define novel functions of the viral protein NS5. The vast amount of information provided by this study is currently being used to validate protein-protein interactions in DENV and ZIKV infection.