PIGR and infection: In M. japonicus, WSSV interacts with a soluble C-type lectin (CTL) through the VP28 protein to promote its infection (20), whereas the binding of WSSV envelope protein VP24 to the polymeric immunoglobulin receptor (pIgR) facilitates viral entry via the pIgR-CaM-clathrin-mediated endocytic pathway (21).