Construction and Immunogenicity Study Of A Newly Construct DNA Vaccine Candidate Against Tuberculosis In Mice

Abstract. In this study, a plasmid DNA encoding Mtb8.4, 30kDa (Ag85B) and 32kDa (Ag85A) genes of M. tuberculosis was constructed as an alternative vaccine candidate against TB. Using assembly polymerase chain reaction (PCR) method, the syn-thetic gene, designated as VacIV, was constructed from overlapping oligonucleotides of the desired genes. The VacIV gene was cloned into an expression vector, pVAX1 © to produce a DNA vaccine candidate namely pVaxVacIV. The immunogenicity of pVaxVacIV was then tested in mice. Mice were immunized intramuscularly with pVaxVacIV. Control mice were immunized with the blank vector (pVAX1©). The splenocytes were cultured with purified protein derivatives (PPD), rVacIV protein or Mtb8.4 synthetic peptide for lymphocytes transformation test (LTT) and cytokines assay. Sera were also collected to determine the level of serum IgG subclasses. Our results showed that lymphocytes from mice immunized with the pVaxVacIV secreted significantly higher level of interferon gamma (IFN-γ) but not Interleukin-4 (IL-4) compared to the control mice. Mice immunized with pVaxVacIV also showed high stimulation index and high ratio of IgG2a:IgG1 as compared to control group. These results sug-gested that pVaxVacIV immunogenic in mice and can be further developed as a potential vaccine candidate for TB