Evaluation of Immunogenicity of Divalent DNA Vaccine Encoding Brucella melitensis Omp31 and P39 Genes in Balb/c Mice

Introduction & Brucella is a facultative intracellular pathogen and one of the etiologic agents of brucellosis that can infect humans and domestic animals. Attenuated strains such as B. melitensis Rve1 and B. abortus S19 and Rb51 are being used to control brucellosis in domestic animals. However, no safe and effective vaccine is available for human use. This study was designed to evaluate the immunogenicity and the protective efficacy of a divalent fusion DNA vaccine encoding both the B. melitensis Omp31 protein and P39 protein, designated pCDNA3 recombinant vector. This experimental study was performed in Biotechnology Research Center of Islamic Azad University, Shahrekord branch in summer, 1386. Construction of pCDNA3 recombinant vector containing Omp31 and P39 genes of B. melitensis was completed. Then, 12 Balb/c mice were immunized intramuscularly with 100 mg per 50 micro liters of this DNA vaccine. Control mice, 12 Balb/c mice, were simultaneously injected with PBS. During the 1st, 7th, 15th and 30th days the mice received the injections. Afterwards, the ELISA cytokine assay was performed and data were analyzed by SPSS software. Intramuscular injection of the divalent DNA vaccine elicited cellular immune responses in Balb/c mice. The ELISA cytokine assay with serum of vaccinated mice showed high level of IFN-γ and low changes of IL-4 in compare with control mice. Use of divalent genetic vaccine based on the Omp31 and P39 genes can elicit a strong cellular immune response against Brucellosis.