Heat shock protein HSPA1A promotes porcine epidemic diarrhea virus replication by targeting the viral RNA-dependent...

Porcine epidemic diarrhea virus (PEDV) is a highly pathogenic virus causing severe diarrhea in piglets. Upon infecting the host cells, PEDV assembles a viral core replication-transcription complex (RTC) that drives viral genome synthesis. NSP12, a core component of RTC possessing RNA-dependent RNA polymerase (RdRp) activity, functions in concert with accessory factors NSP7 and NSP8. Using immunoprecipitation coupled with mass spectrometry (IP-MS), we identified the critical host factor HSPA1A as an interactor of PEDV NSP12, essential for supporting PEDV replication in LLC-PK1 cells. Notably, knockout of HSPA1A diminished viral RNA synthesis by decreasing RdRp activity, resulting in a significant decrease in viral replication level. We further demonstrated that HSPA1A plays an essential role in promoting the formation of the RdRp complex (NSP7, NSP8 and NSP12). Beyond interacting with NSP12, HSPA1A also interacts with NSP8 to facilitate the formation of the RdRp complex and enhance the PEDV RdRp activity. Collectively, our findings illuminate a novel mechanism by which the host factor HSPA1A mediates the formation of viral RdRp complex to promote PEDV replication, and provide a potential target for the prevention and control of PEDV.