Porcine reproductive and respiratory syndrome virus exploits ESCRT-II subunit EAP20 for entry and replication.

Porcine reproductive and respiratory syndrome (PRRS), caused by PRRS virus (PRRSV), is a major viral disease that poses a serious threat to the global swine industry. Although progress has been made in understanding its life cycle, the molecular mechanisms underlying PRRSV entry and replication remain incompletely understood. Multiple RNA viruses hijack the endocytic sorting complex required for transport (ESCRT) machinery to orchestrate various stages during infection. In the current study, we identified ESCRT-II subunit ELL-associated protein 20 (EAP20) as an important host factor involved in PRRSV entry and replication. Mechanistically, EAP20 participated in the transport of internalized PRRSV particles to early endosomes via the clathrin-mediated endocytosis pathway. During replication, EAP20 interacted with PRRSV nonstructural protein (Nsp) 2, Nsp5, and Nsp9. Specifically, EAP20 anchored the core replicase Nsp9 on the perinuclear endoplasmic reticulum (ER) and coordinated with the transmembrane proteins Nsp2/Nsp5 to form ER-derived double-membrane vesicles. Collectively, our findings demonstrate that PRRSV exploits EAP20 for viral entry and replication, highlighting EAP20 as a novel proviral factor and a potential antiviral target. IMPORTANCE: PRRSV remains one of the most economically significant pathogens in the global swine industry. Current control strategies are largely hindered because PRRSV pathogenesis has not been fully elucidated. In this study, we identified EAP20, a core subunit of ESCRT-II, as a multifaceted proviral factor that participated in PRRSV entry and replication. These findings provide new insights into the interplay between PRRSV and the host ESCRT machinery, laying a foundation for the development of more effective strategies for PRRS control.