DNA Prime and Protein Boost Immunization with Combined SOD-L7/L12 Antigen Confers Protection to Mice against Brucella Abortus 544 Challenge

摘要

Brucella abortus is an intracellular pathogen that has zoonotic implication. Currently used live attenuated vaccines have several limitations including interference in serodiagnosis of clinical infection and presence of residual virulence in the vaccine strains. There is an urgent need to develop a safe vaccine for control of brucellosis. Here, we describe development of a DNA vaccine construct by combining two immunodominant antigens namely, copper–zinc superoxide dismutase (Cu–Zn SOD) and L7/L12 ribosomal protein. Both the genes were amplified and ligated together to produce the DNA vaccine construct. The combine gene was further expressed in prokaryotic system to produce recombinant fusion protein. A DNA prime–protein boost strategy was followed to immunize mice. Strong immune response dominated by IgG2a subtype shows immune skewing towards Th1 type. Further we have showed that combined antigen conferred significantly higher level of protection against a challenge infection as compare to single antigen immunization. However, the level of protection conferred by combined antigen was lower that the S19 live vaccine. Our report shows the potential of SOD: L7/L12 combined antigen as candidate vaccine eliciting strong immune response against experimental murine brucellosis