White spot syndrome virus infection activates Caspase 1-mediated cell death in crustacean.

In vertebrates, pyroptosis is an intense inflammatory form of programmed cell death. This death pathway is critical for controlling pathogenic infection. In invertebrates, however, due to the lack of adaptive immune response, it is still elusive whether Caspase 1-dependent cell death pathway exists. In this study, our data showed that Caspase 1-mediated cell death was activated by white spot syndrome virus to counteract virus infection. Caspase 1 had a higher expression in hemocytes and lymphoid-like organ in shrimp and WSSV infection was promoted upon the inhibition of Caspase 1 enzymatic activity. IL-1β-like protein was identified as the substrate of Caspase 1 and its interaction with Caspase 1 was validated ectopically and endogenously. Moreover, IL-1β like protein was released into extracellular contents under WSSV infection and Prophenoloxidase system was activated, resulting in the reduction of WSSV. Our data unraveled a previously unidentified mechanism through which Caspase 1-dependent cell death controlled virus infection in shrimp.