SIRT-1 connects autophagy and release of virus-containing vesicles during picornavirus infection

Enterovirus D68 is a re-emerging enterovirus which causes acute respiratory illness in infants. EV-D68 infection has recently been associated with Acute Flaccid Myelitis, a severe polio-like neurological disease that causes limb weakness and loss of muscle tone in infants. There is currently no FDA-approved drug or prophylactic vaccine against EV-D68. Here, we investigated the role of the histone deacetylase, SIRT-1, in autophagy and EV-D68 infection. We show that SIRT-1 plays an important role in both autophagy and EV-D68 infection. siRNA-mediated knockdown of the cellular protein blocks basal and stress-induced autophagy and reduces EV-D68 extracellular viral titers. The proviral activity of SIRT-1 does not require deacetylase activity, since transient expression of both wild-type and deacetylase-inactive SIRT-1 mutant plasmids increased EV-D68 release. In non-lytic conditions, EV-D68 is primarily released in extracellular vesicles, and SIRT-1 is required for this process. Knockdown of SIRT-1 further impedes EV-D68 release in the autophagy-deficient ATG-7 knockout cells. Knockdown of SIRT-1 also decreases titers of poliovirus (PV) and SARS-CoV-2, but not Coxsackievirus-B3 (CVB3). CVB3 is the only tested virus that fails to induce SIRT-1 translocation to the cytosol. Our data suggest a correlation between SIRT-1 translocation during viral infection and extracellular vesicle-mediated non-lytic release of infectious viral particles. SIGNIFICANCE Picornaviruses, including EV-D68, constitute a significant cause of human disease. EV-D68 infection generally causes mild respiratory tract infection in infants but has recently been implicated in a severe polio-like neurological disease, AFM. Given the lack of prophylactic vaccines or antivirals against EV-D68, identifying host factors that modulate EV-D68 infection is crucial. Here, we show that SIRT-1 regulates autophagy and EV-D68 infection. Knockdown of SIRT-1 blocked autophagy and impeded the non-lytic release of EV-D68 in extracellular vesicles. We also show that SIRT-1 modulates the release of SARS-CoV-2 and poliovirus but not Coxsackievirus-B3 virus. Our data suggest that many RNA viruses require SIRT-1 for egress and that targeting SIRT-1 could constitute a broad-spectrum antiviral strategy.