Immunity Efficacy of a DNA Vaccine Encoding VirB8 of Brucella in BALB/c Mice

Brucella is a intracellular bacterial pathogen. Due to current available attenuated vaccine against it has certain defects. The development of an effective DNA vaccine against brucellosis is an area of intense research. This study was conducted to evaluate the immunogenicity and protective efficacy of a DNA vaccine encoding Brucella VirB8 which is a essential components of type IV Secretion Systems (T4SSs) and bacterial virulence factor. The BALB/c mice inoculated Intramuscularly with pCDNA-VirB8 plasmid developed both humoral and cellular immune responses. They produced VirB8-specific antibodies with a dominance of IgG2a over IgG1 and a T-cell-proliferative response. Recombinant VirB8 also induced the production of gamma Interferon but not Interleukin-4 (IL-4) after stimulating lymphocytes with it in vitro. This suggested the induction of a typical T-helper-1-dominated immune response in mice. The protective ability of the DNA vaccine was evaluated by systemic bacterial clearance after challenging the mice with S2. The pCDNA-VirB8 induced a significant level of protection in BALB/c mice. Altogether, these data suggest that VirB8 is a good candidate for studies of DNA vaccination against brucellosis in future.