The African swine fever virus MGF360-16R protein functions as a mitochondrial-dependent apoptosis inducer by competing with BAX to bind to the HSP60 protein.

Induction of cell apoptosis is a critical pathogenic feature of the African swine fever virus (ASFV), a devastating threat to the world pig industry, but the underlying mechanisms have remained unclear. Here, we report the genome-wide screening and identification of 27 ASFV-encoded apoptosis inducers. Of them, the viral protein MGF360-16R was found to be a mitochondria-targeting protein and exhibits strong activity to induce mitochondrial-dependent apoptosis. Interestingly, this protein exhibits a dynamic distribution pattern during viral infection of porcine macrophages; it is mainly localized to the viral factory in the early stage and then shifts a portion to mitochondria in the late stage, a timing that coincides with virus-induced apoptosis. Mechanistically, MGF360-16R interacts with and competes for the cellular heat shock protein 60 (HSP60), and this results in the release of BAX from the HSP60-BAX complex, leading to the activation of BAX and induction of apoptosis. The ASFV mutant lacking MGF360-16R showed a reduced ability to induce cellular apoptosis, highlighting the complex nature of ASFV-induced cell apoptosis. Overall, our study adds a new function to MGF360-16R and reveals a novel mechanism of ASFV-mediated cell apoptosis. IMPORTANCE: ASFV is a complex virus with a huge genome and numerous encoded proteins. Induction of cell apoptosis is associated with pathological damage in pigs caused by ASFV, but its inducers and underlying mechanisms remain unclear. Through genome-wide screening, the viral protein MGF360-16R was identified as a potent apoptosis inducer with a unique localization transfer from the viral factory to mitochondria during ASFV infection of porcine macrophages. MGF360-16R induces apoptosis by interacting with the cellular HSP60 protein to release BAX from the HSP60-BAX complex in a competitive binding manner. Our research findings not only reveal a novel function of MGF360-16R but also provide clues for understanding the pathogenesis of ASFV and potentially developing new therapeutic strategies.