Bombyx mori Akirin hijacks a viral peptide vSP27 encoded by BmCPV circRNA and activates the ROS-NF-κB pathway against viral infection.

Bombyx mori cypovirus (BmCPV), a member of the family Reoviridae, is a model of Cypovirus, has a 10 segmented double-stranded RNA genome. However, so far, only one viral small peptide vSP27 with negative regulation on viral infection was identified; the mechanisms underlying host-BmCPV interaction are still unknown. Here, we identified that vSP27 was translated from a BmCPV derived circular RNA (circRNA-vSP27). Subsequently, results showed that vSP27 induced generation of ROS activated the NF-κB signaling pathway, induced the expression of antimicrobial peptides, and suppressed BmCPV infection. On the other hand, we identified a nuclear protein Akirin that could hijack vSP27, positively regulate the NF-κB pathway, and lead to inhibiting the viral infection. Altogether, our data suggested that BmCPV derived circRNA-vSP27 with small peptide translation activity may be employed by the host immunity in defense against the BmCPV infection.