The role of white spot syndrome virus (WSSV) VP466 protein in shrimp antiviral phagocytosis

Widespread evidence indicates that the structural proteins of virus play very important roles in virus–host interactions. However, the effect of viral proteins on host immunity has not been addressed. Our previous studies revealed that the host shrimp Rab6 (termed as PjRab previously), tropomyosin, β-actin and the white spot syndrome virus (WSSV) envelope protein VP466 formed a complex. In this study, the VP466 protein was shown to be able to bind host Rab6 protein and increase its GTPase activity in vivo and vitro. Thus, VP466 could function as a GTPase-activating protein (GAP) of Rab6. In the VP466-Rab-actin pathway, the increase of the Rab6 activity induced rearrangements of the actin cytoskeleton, resulting in the formation of actin stress fibers which promoted the phagocytosis against virus. Therefore our findings revealed that a viral protein could be employed by host to initiate the host immunity, representing a novel molecular mechanism in the virus–host interaction. Our study would help to better understand the molecular events in immune response against virus infection in invertebrates.

► The VP466 protein could bind host Rab6 protein and increase its GTPase activity.
► The viral protein could be employed by host to initiate the host immunity.
► The increase of the Rab6 activity promoted host defense against virus.