Identification of host proteins interacting with NS3 protein of Bluetongue virus

A wide range of species contract a haemorrhagic disease caused by Bluetongue virus (BTV), which is transmitted by hematophagous midges of Culicoides species. The virus shows variation in its pathogenicity and virulence between the mammalian and insect hosts, implicating the role of host proteins in its life cycle. NS3, a versatile protein of BTV, performs a major role in viral egress by acting as perforin. Multifunctional roles of NS3 have also been reported in viral pathogenesis, but there are critical gaps in explaining the exact mechanisms of its crosstalk with the host, creating the space for NS3-host interaction studies. In this study, we report the screening of host proteins interacting with NS3 protein of BTV using yeast-two hybrid (Y2H) assay. An ovine cDNA library derived from sheep lung and the truncated NS3 (NS3 t ) bait were constructed and evaluated for competency parameters. Following stringent screening, 37 putative host interaction partners were identified, of which eight proteins were selected for validation using alternative yeast-based assays; seven of these interactions were confirmed as positive. NAP1L1/NS3 interaction was further verified with GST pull-down, co-immunoprecipitation and mammalian two-hybrid assays. The results indicate that NAP1L1, a protein involved in nucleosome assembly and cell cycle regulation, interacts with the BTV NS3 protein.