Porcine reproductive and respiratory syndrome virus degrades TANK-binding kinase 1 via chaperon-mediated autophagy to suppress type I interferon production and facilitate viral proliferation

Porcine reproductive and respiratory syndrome virus (PRRSV) has led to significant economic losses in the global swine industry. Type I interferon (IFN-I) plays a crucial role in the host’s resistance to PRRSV infection. Despite extensive research showing that PRRSV employs multiple strategies to antagonise IFN-I induction, the underlying mechanisms remain to be fully elucidated. In this study, we have discovered that PRRSV inhibits the production of IFN-I by degrading TANK-binding kinase 1 (TBK1) through chaperon-mediated autophagy (CMA). From a mechanistic standpoint, PRRSV nonstructural protein 2 (Nsp2) increases the interaction between the heat shock protein member 8 (HSPA8) and TBK1. This interaction leads to the translocation of TBK1 into lysosomes for degradation, mediated by lysosomal-associated membrane protein 2A (LAMP2A). As a result, the downstream activation of IFN regulatory factor 3 (IRF3) and the production of IFN-I are hindered. Together, these results reveal a new mechanism by which PRRSV suppresses host innate immunity and contribute to the development of new antiviral strategies against the virus.