Abstract

Completion of autophagy through autophagosome-lysosome fusion represents a critical regulatory checkpoint that is frequently manipulated during viral infection, however, how coronaviruses exploit this terminal step remains incompletely understood. Porcine epidemic diarrhea virus (PEDV), a highly pathogenic alphacoronavirus, has been reported to induce autophagy, but whether and how complete autophagic flux contributes to viral replication is unclear. Here, using a genome-wide CRISPR/Cas9 knockout screen in Vero cells, we identify the HOPS complex subunits VPS33A and VPS18 as essential host factors for PEDV infection. Genetic ablation of either VPS33A or VPS18 profoundly suppresses viral progeny production and arrests autophagic flux at the autophagosome stage, demonstrating that PEDV replication is associated with HOPS-mediated autolysosome formation. Domain-mapping analyses further reveal that the structural integrity of VPS33A and the α-solenoid plus RING domains of VPS18 are indispensable for both autophagosome-lysosome fusion and efficient viral replication. Mechanistically, we show that PEDV non-structural proteins nsp3 and nsp4 physically interact with VPS33A and VPS18. While either protein alone initiates autophagosome formation, their coordinated action contributes to drive complete autophagy in a HOPS-dependent manner. Collectively, our findings uncover a coronavirus strategy that actively promotes autophagic completion through VPS33A and VPS18, two core subunits of the HOPS complex, to support replication, thereby establishing autolysosome formation as a critical host process exploited by PEDV.