Bombyx mori nucleopolyhedrovirus utilizes a clathrin and dynamin dependent endocytosis entry pathway into BmN cells

Bombyx mori nucleopolyhedrovirus (BmNPV) is a leading cause of silkworm mortality and economic loss to sericulture. The entry of BmNPV budded virus (BV) into host cells is a fundamental process required for the initiation of infection. However, our understanding of the mechanism of virus entry is limited and it is unclear whether BV enter BmN cells via clathrin-mediated endocytosis. In this study, we found that BV enter BmN cells through a low-pH-dependent endocytosis pathway. Inhibition assays, transmission electron microscopy (TEM) analysis, and small interfering RNAs (siRNAs) knockdown assays revealed that BV entry into BmN cells is mediated by clathrin-dependent endocytosis. Moreover, after treated with dynasore, an inhibitor of dynamin, BmNPV entry was markedly reduced, indicating that dynamin also participates in the efficient internalization of BmNPV. In addition, suppression of Rab5, Rab7 or Rab11 through siRNAs demonstrated that BV requires early and late endosomes for endocytosis in infection of BmN cells. Taken together, BmNPV uses a clathrin- and dynamin-mediated endocytic pathway into BmN cells that requires participation of Rab5 and Rab7 but not Rab11.