Survival rate of vaccinated and non-vaccinated grouper at different times after challenge with TGIV. (A) To test the vaccine efficacy, three treatments were analyzed: (1) vaccination via intraperitoneal injection of recombinant MCP protein, followed by TGIV infection; (2) mock-vaccination via intraperitoneal injection of PBS, followed by TGIV infection; and (3) mock-immunization with PBS only. All groups were carried out in triplicates of 15 fish. The figure shows the average survival rate of the three different groups. The vaccine apparently enhanced the survival rate against TGIV infection with a RPS of about 86% on day 21 post-infection; (B) An autopsy was performed on the TGIV-infected and non-infected fish of the mock-vaccinated treatment. Enlargement of spleen, a clinical sign of TGIV infection, was observed in the infected fish but was absent in the non-infected fish. Arrows indicate the spleens; (C) The evidence of TGIV replication in the infected fish was assayed. The MCP transcript was detected by RT-PCR in the head kidney and spleen of the infected fish but absent in the non-infected control. * p < 0.05–0.01, ** p < 0.01.