The non-structural 3 (NS3) protein of dengue virus type 2 interacts with human nuclear receptor binding protein and is associated with alterations in membrane structure

Flaviviral infections produce a distinct array of virus-induced intracellular membrane alterations that are associated with the flaviviral replication machinery. Currently, it is still unknown which flaviviral protein(s) is/are responsible for this induction. Using yeast two-hybrid and co-immunoprecipitation analyses, we demonstrated that the NS3 protein of dengue virus type 2 interacted specifically with nuclear receptor binding protein (NRBP), a host cellular protein that influences trafficking between the endoplasmic reticulum (ER) and Golgi, and that interacts with Rac3, a member of the Rho-GTPase family. Co-expression of NS3 and NRBP in baby hamster kidney cells exhibited significant subcellular co-localization, and revealed the redistribution of NRBP from the cytoplasm to the perinuclear region. Furthermore, a set of membrane structures affiliated with the rough ER at the perinuclear region was induced in cells transfected with NS3. These structures are reminiscent of the virus-induced convoluted membranes previously observed in flavivirus-infected cells. This interaction between dengue viral and host cell proteins as well as the formation of the NS3-induced membrane structures suggest that NS3 may subvert the role of NRBP in ER-Golgi trafficking.