Induction of immune response in mice with a DNA vaccine encoding outer membrane protein (omp31) of Brucella melitensis 16M

Brucellosis causes serious economic losses to goat farmers by way of reproductive losses in the form of abortions and stillbirths. Nucleic acid vaccines provide an exciting approach for antigen presentation to the immune system. In this study, we evaluated the ability of DNA vaccine encoding the omp31 protein of Brucella melitensis 16M to induce cellular and humoral immune responses in mice. We constructed eukaryotic expression vectors called pTargeTomp31, encoding outer membrane protein (omp31) of B. melitensis 16M. pTargeTomp31 was injected intramuscularly three times, at 3-week intervals in groups of mice 6 weeks of age. pTargeTomp31 induced good antibody response in ELISA . pTargeTomp31 elicited a T-cell-proliferative response and also induced a strong gamma interferon production upon restimulation with either the omp31 antigen or B. melitensis 16M extract. We also demonstrate that animals immunized with this plasmid elicited a strong and long-lived memory immune response. Furthermore, pTargeTomp31 elicited a typical T-helper 1-dominated immune response in mice, as determined by immunoglobulin G isotype analysis. This vaccine also provided the moderate degree of protection to the mice. This study for the first time focuses on DNA immunization of a gene from B. melitensis. These results may lead to the development of a DNA-based vaccine for the control of brucellosis in goats.