Protective immunity to VHS in rainbow trout (Oncorhynchus mykiss, Walbaum) following DNA vaccination

Rainbow trout fingerlings were immunized by intramuscular injection of a plasmid DNA vector encoding the viral haemorrhagic septicaemia virus (VHSV) glycoprotein (G) or nucleocapsid protein (N) genes under the control of a cytomegalovirus promoter. Challenge with VHSV 52 days later demonstrated that both viral genes, and the G gene in particular, were able to induce protective immunity against VHS. In contrast to sera taken from fish injected with the N gene, neutralizing antibody activity could be detected both before and after challenge in the sera of a major proportion of the fish injected with the G gene.