BmAtg13 promotes the replication and proliferation of Bombyx mori nucleopolyhedrovirus.

Autophagy is a cell adaptive response that involves the process of microbial infections. Our previous study has indicated that Bombyx mori nucleopolyhedrovirus (BmNPV) infection triggers the complete autophagic process in BmN-SWU1 cells, which is beneficial to the viral infection. Autophagy-related (ATG) protein ATG13, as part of the ULK complex (a serine-threonine kinase complex composed of ULK1, ULK2, ATG13, ATG101, and FIP200), is the most upstream component of the autophagy pathway, and how it affects virus infections will improve our understanding of the interaction between the virus and the host. This study has determined that the overexpression of the BmAtg13 gene promotes the expression of viral genes and increases viral production in BmN-SWU1 cells, whereas knocking down the BmAtg13 gene suppresses BmNPV replication. Moreover, the BmAtg13 overexpression transgenic line contributed to viral replication and increased mortality rate of BmNPV infection. In contrast, the BmAtg13 knockout transgenic line reduced viral replication 96 h post-infection. Furthermore, BmATG13 directly interacted with viral protein BRO-B, forming a protein complex. Taken together, the findings of this study suggest that BmATG13 may be utilized by the BRO-B protein to promote BmNPV replication and proliferation, which, in turn, provides important insights into the mechanism that autophagy influences viral infection.