Coxsackievirus A10 blocks autophagosome-lysosome fusion to promote viral nonlytic spread and inflammatory cytokine release.

We aimed to demonstrate whether coxsackievirus A10 (CV-A10) perturbed the fusion between autophagosomes and lysosomes to cause viral nonlytic spread and inflammatory cytokine release at the blood-brain barrier (BBB), thereby contributing to neuropathological damage. CV-A10-induced autophagic secretory pathway at the cellular level was examined using western blot, immunofluorescence, and flow cytometry methods. Then, the mechanism of autophagic secretory pathway in the neuropathogenesis of CV-A10 infection was demonstrated by constructing a suckling mouse model and combining behavioral, pathological, and molecular biological methods. The expression levels of autophagic secretory pathway-related proteins, extracellular inflammatory cytokines, and viral particles were significantly increased during CV-A10 infection. Moreover, 3-methyladenine significantly impeded the levels of autophagic secretory pathway-related proteins and the release of inflammatory cytokines or viruses; GW4869 and chloroquine partially suppressed these changes, whereas bafilomycin A1 had no obvious effects on these changes, implying that the autophagic secretory pathway without endosome or lysosome involvement might represent a new mode of inflammatory cytokine release and virus spread from intracellular to extracellular environments. Finally, an in vivo suckling mouse model further found that treatment with GW4869 significantly relieved the clinical symptoms and mortality of CV-A16-infected mice and inhibited the spread of the virus and the release of inflammatory cytokines. Our findings provide the first evidence that CV-A10 might trigger the autophagic secretory pathway by limiting autophagosome-lysosome fusion to complete the transmembrane nonlytic transmission of the virus at the BBB and the secretion of inflammatory cytokines, ultimately accelerating neuropathological damage.IMPORTANCEThis study provided the first evidence that coxsackievirus A10 (CV-A10) might use the autophagic secretory pathway for nonlytic intercellular release to complete transmembrane transmission at the blood-brain barrier and inflammatory cytokine secretion to accelerate the formation of neuroinflammation in infected hosts, which not only gave us a new understanding of the neuropathogenesis caused by CV-A10 but also offered a promising target to develop CV-A10 antiviral drugs.