Identification of heat shock protein A9 as a Tembusu virus binding protein on DF-1 cells

This study attempts to identify receptor elements for Tembusu virus (TMUV) on DF-1 cells. Using co-immunoprecipitation and virus overlay protein binding assays, we identified a TMUV-binding protein of approximately 70-kDa on DF-1 cell membranes. Mass spectroscopy identified the protein to be heat shock protein (HSP) A9, which was reconfirmed by an anti-HSPA9 antibody. Indirect immunofluorescence demonstrated a significant degree of colocalization between HSPA9 and TMUV on cell surface. Additionally, an antibody against HSPA9 could inhibit TMUV infection in DF-1 cells in a dose-dependent manner. These results might suggest that HSPA9 is a putative receptor for TMUV.