| DNA-based immunization was investigated as a possible approach to prevent Renibacterium salmoninarum infection in Atlantic salmon ( Salmo salar). Two DNA vaccine prototypes, pNCSV3 and pNCSV6, encoding a portion of R. salmoninarum p57 major protein antigen under the control of the simian virus 40 (SV40) late promoter and the cytomegalovirus (CMV) promoter respectively, were constructed. Transfection of chinook salmon embryonic (CHSE-214) cell cultures with either prototypes resulted in detectable transcriptional activity. Immunocytochemical analysis revealed that authentic epitopes were conserved in the protein expressed by pNCSV6, however, no perceptible signal was obtained from pNCSV3.; Efficiency of the DNA vaccines to protect Atlantic salmon was evaluated in a co-habitation challenge. Microbiological examination of the kidneys revealed similar bacterial counts for both vaccinated and control groups indicating that the vaccinated fish where not protected from infection. Nonetheless, transcriptional activity in the fish apical muscle was detected for both prototypes 68 days following vaccination. |
