Bombyx mori nucleopolyhedrovirus F-like protein Bm14 is a cofactor for GP64-Mediated efficient infection via forming a complex on the envelope of budded virus

Our previous study showed that Bombyx mori nucleopolyhedrovirus F-like protein Bm14 is involved in infectious BV production and its deletion reduces the production rate. However, the peculiar relationship between Bm14 and GP64, two major BV envelope proteins, is still unknown. Here, we demonstrated the predominant distribution of Bm14 in BVs rather than in ODVs. Further experiments revealed that the absence of Bm14 moderately reduced trafficking of GP64 to the plasma membrane and impaired GP64-mediated fusion activity. Coimmunoprecipitation analysis demonstrated the associations of Bm14 with GP64, and confocal microscopy also displayed their colocalization throughout nonviral or viral infection. More interestingly, an approximately 270-kDa complex containing Bm14 and GP64 was detected in the cytoplasm using BN-PAGE and Western blotting. The disruption of Bm14 resulted in a subcomplex of similar to 190 kDa. Collectively, Bm14 functions as a cofactor of GP64 via forming a complex on the surface of BVs, thus affecting the efficient infection.