Recombinant VP28 Produced by Cell-Free Technique Confers Protection in Kuruma Shrimp (Marsupenaeus japonicus) Against White Spot Syndrome Virus

The protective efficacy of oral delivery and intramuscular (i.m.) injection of a recombinant protein, rVP28 derived from white spot syndrome virus (WSSV) and synthesized using wheat germ cell-free technology was investigated in kuruma shrimp (Marsupenaeus japonicus). Shrimps were administered with the unpurified rVP28 and challenged with WSSV. Expression of innate immune-related genes was examined in intestine, heart, and lymphoid organ at 1, 3 and 7 days after oral-administration. Shrimps received rVP28 protein through i.m. injection or oral route and then challenged with WSSV displayed higher survival (90 and 85.7%, respectively) compared to the respective control groups. A significant up-regulation (P<0.01) of innate immune-related genes, such as Rab7, penaeidin, lysozyme and crustin, was noticed in orally treated shrimps. Our results indicate that this recombinant protein could elevate immune responses and protection in kuruma shrimp and therefore would have potential utility against WSSV infection in shrimp aquaculture.