The nonlytic cellular egress of picornaviruses in extracellular vesicles is likely to be important in disease pathogenesis, but the mechanism(s) underlying this process and the origins of the membranes surrounding virions exiting the cell are poorly understood. We describe a quantitative proteomics analysis of quasi-enveloped hepatitis A virus (eHAV) virions that shows capsids are selected as cargo for vesicular export via a highly specific process, and that infectious eHAV virions possess a host protein complement similar to that of exosomes with CD9 and DPP4 displayed on their surface. eHAV-associated proteins are highly enriched for endolysosomal components and lack markers of autophagy, suggesting an exosome-like mechanism of endosomal sorting complex required for transport-mediated eHAV biogenesis involving endosomal budding that is distinct from the autophagosome-mediated release proposed previously for enteroviruses
