Mitophagosomes induced during EV-D68 infection promote viral nonlytic release

Enterovirus-D68 (EV-D68) is a plus-strand RNA virus that primarily causes infant respiratory infections. In rare pediatric cases, infection with EV-D68 has been associated with acute flaccid myelitis, a polio-like paralytic disease. We have previously demonstrated that EV-D68 induces nonselective autophagy for its benefit. Here, we demonstrate that EV-D68 induces mitophagy, the specific autophagic degradation of mitochondria. EV-D68 infection induces mitophagosome formation and several hallmarks of mitophagy, including mitochondrial fragmentation, mitochondrial membrane potential loss, and Parkin translocation to the mitochondria were observed in EV-D68 infected cells. The 3C protease of EV-D68 cleaves the mitochondrial fusion protein, mitofusin-2, near the C-terminal HR2 domain to induce mitochondrial fragmentation, and these fragmented mitochondria colocalized with double-stranded RNA (dsRNA), which labels viral RNA replication sites after peak viral RNA replication. Depleting components of mitophagy signaling specifically reduced EV-D68 release without impacting viral intracellular titers. Our results suggest that whereas the machinery of macroautophagy supports various stages of enterovirus replication, including viral genomic RNA replication and capsid maturation, mitophagy is the specific form of autophagy that regulates the nonlytic release of enteroviruses from cells.