Development of DNA Vaccines against Nocardia seriolae Infection in Fish

Abstract

This study presents the development of DNA vaccines against nocardiosis, using the Antigen 85-like (Ag85L) gene in Nocardia seriolae. An expression plasmid encoding Ag85L (pAg85L^wt) and codon-optimized Ag85L (pAg85L^opt) was intramuscularly injected into amberjack Seriola dumerili. Survival rates of the pAg85L^wt, pAg85L^opt vaccinated group and PBS-injected group as a negative control were 88%, 98% and 51%, respectively, at 40 days after the N. seriolae challenge. In addition, the N. seriolae bacterial count in the spleen was significantly lower in the pAg85L^wt and pAg85L^opt vaccinated fish than in the PBS-injected fish (P < 0.05). These results suggest that the DNA vaccines pAg85L^wt and pAg85L^opt conferred protective efficacy against N. seriolae infection in amberjack.