PGAM5 degrades PDCoV N protein and activates type I interferon to antagonize viral replication

ABSTRACT In recent years, porcine deltacoronavirus (PDCoV) has become a new intestinal coronavirus in pigs, rapidly spreading across multiple countries and causing significant financial losses in the global pig industry. Currently, no effective commercial vaccine is available to prevent this virus’ spread. Thus, it becomes crucial to investigate the interaction between the virus and its host to acquire valuable insights into the underlying mechanisms of viral replication and develop innovative strategies for preventing and controlling PDCoV. This study specifically focuses on exploring the regulatory effects of PGAM5, a mitochondrial protein, during viral proliferation. Our findings suggest that PDCoV infection hinders the expression of PGAM5 in LLC-PK1 cells. Additionally, it was also found that PGAM5 facilitates the degradation of the PDCoV N protein via the interaction with it, thereby inhibiting viral proliferation. Notably, the degradation of the PDCoV N protein by PGAM5 is mediated through its interaction with the cargo receptor P62 and the E3 ubiquitination ligase STUB1 during the protein degradation process. Furthermore, our results demonstrate that PGAM5 enhances the phosphorylation of IRF7, resulting in increased expression of type I interferon through its interaction with MyD88 and TRAF3, ultimately inhibiting PDCoV replication. Collectively, these findings elucidate the antiviral mechanism of PGAM5, which involves the degradation of the PDCoV N protein and activation of type I interferon to counteract viral replication. The obtained results emphasize the potential of PGAM5 as the novel target for preventing and treating PDCoV. IMPORTANCE As a member of the δ-coronavirus family, porcine deltacoronavirus (PDCoV) is a vital reason for diarrhea in piglets, which can contribute to high morbidity and mortality rates. Initially identified in Hong Kong in 2012, the virus has rapidly spread worldwide. During PDCoV infection, the virus employs evasion mechanisms to evade host surveillance, while the host mounts corresponding responses to impede viral replication. Our research has revealed that PDCoV infection down-regulates the expression of PGAM5 to promote virus replication. In contrast, PGAM5 degrades PDCoV N through autophagy by interacting with the cargo receptor P62 and the E3 ubiquitination ligase STUB1. Additionally, PGAM5 interacts with MyD88 and TRAF3 to activate the IFN signal pathway, resulting in the inhibition of viral replication.