Bombyx mori RPS3 participates in the UV damage repair of Bombyx mori nucleopolyhedrovirus by interacting with Bm65.

UV radiation in sunlight easily causes the inactivation of baculovirus biopesticides. However, the DNA repair mechanisms of most baculoviruses after UV radiation remain unclear. Bombyx mori nucleopolyhedrovirus (BmNPV) Bm65 has been proven to be a specific endonuclease that cleaves UV-induced DNA damage, which is crucial for UV damage repair of viruses. Here, we further explored the relationship between host ribosomal protein Bombyx mori RPS3 (BmRPS3), viral protein Bm65 and UV radiation. Our results showed that BmRPS3 was mainly located in the cytoplasm, not aggregated at the sites of viral DNA in infected BmN cells. By constructing truncated protein, the N-terminal KH-2 domain of BmRPS3 was demonstrated to be closely related to UV damage repair. When there was no UV damage, Bm65 and BmRPS3 were not colocated and did not interact with each other. After UV radiation, BmRPS3 translocated from the cytoplasm to UV-induced DNA damage sites, relied on the interaction with Bm65 to regulate the UV damage repair and proliferation of BmNPV. In the early stages of viral infection, BmRPS3 promoted the expression of Bm65. These findings about specific interaction between BmRPS3 and Bm65 only after UV radiation provided a reference for deeper understanding of how the selective interaction between viruses and hosts regulated life activities under different conditions.