A Coxsackievirus B1-mediated nonlytic Extracellular Vesicle- to-cell mechanism of virus transmission and its possible control through modulation of EV release

Like most non-enveloped viruses, CVB1 mainly uses cell lysis to spread. Details of a nonlytic virus transmission remain unclear. Extracellular Vesicles (EVs) transfer biomolecules between cells. We show that CVB1 entry into HeLa cells results in apoptosis and release of CVB1-induced 'medium-sized' EVs (CVB1i- mEVs). These mEVs (100-300 nm) harbour CVB1 as shown by immunoblotting with anti- CVB1-antibody; viral capsids were detected by transmission electron microscopy and RT- PCR revealed CVB1 RNA. The percentage of mEVs released from CVB1-infected HeLa cells harbouring virus was estimated from TEM at 34 %. Inhibition of CVB1i- mEV production, with calpeptin or siRNA knockdown of CAPNS1 in HeLa cells limited spread of CVB1 suggesting these vesicles disseminate CVB1 virions to new host cells by a nonlytic EV- to- cell mechanism. This was confirmed by detecting CVB1 virions inside HeLa cells after co-culture with CVB1i- mEVs; EV release may also prevent apoptosis of infected cells whilst spreading apoptosis to secondary sites of infection.

Automated summary

CVB1, a non-enveloped virus, spreads using cell lysis and extracellular vesicles (EVs). In this study, it was discovered that CVB1 induces apoptosis and releases CVB1-induced 'medium-sized' EVs (CVB1i-mEVs) that contain the virus. These EVs disseminate CVB1 to new host cells through a non-lytic EV-to-cell mechanism.