Selective interaction of BmNPV Bm65 with host proteins before and after ultraviolet radiation

Baculovirus biopesticides are highly susceptible to inactivation by ultraviolet (UV) radiation in sunlight. At present, the DNA repair mechanism in most baculoviruses after ultraviolet (UV) radiation is still unclear. Our previous research found that Bombyx mori nucleopolyhedrovirus Bm65 was a very important UV-specific endonuclease, and the knockout of Bm65 gene increased the sensitivity of BmNPV to UV radiation. Based on the important role of Bm65 in UV-induced DNA repair, we further explored Bm65-interacting proteins using immunoprecipitation and liquid chromatography-mass spectrometry (LC-MS) assays in this study. The interaction between host DNA repair proteins and Bm65 was detected only after UV radiation. Furthermore, when the viruses or hosts were separately damaged by UV radiation, the DNA repair proteins interacting with Bm65 were not completely consistent. We showed for the first time that BmRad23, a key DNA damage recognition protein of host was a UV-dependent interactor of Bm65, and interacted with Bm65 only after UV radiation. It was further found that Bm65 relied on the interaction with BmRad23 to accurately localize at the sites of UV-damaged viral DNA. These results suggested that Bm65 selectively interacted with host proteins before and after UV radiation, and there might be different pathways that Bm65 participated in the UV-induced DNA repair of viruses or hosts.