Humoral immune responses in mice immunized with region of difference DNA vaccine constructs of pUMVC6 and pUMVC7.

Abstract

We aimed to study the antigen-specific antibody responses in mice immunized with recombinant DNA vaccines constructs of pUMVC6 and pUMVC7, containing RD1 and RD9 genes of Mycobacterium tuberculosis. We immunized mice with the parent and recombinant plasmids and sera were collected and tested for antibodies against pure recombinant proteins of RD1 (PE35, PPE68, EsxA, EsxB) and RD9 (EsxV), peptide mixtures of each protein and their individual peptides using enzyme-linked immunosorbent assays. The optical density (OD) values were measured at 405 nm. E/C (OD in antigen-coated wells/OD in antigen uncoated wells) were calculated, and the values of E/C>2 were considered positive. RD1 and RD9 antigen-specific antibodies were detected in sera of mice immunized with the recombinant DNA vaccine constructs (E/C >2.0). With respect to peptide mixtures and single peptides, only PE35mixand P6 of PE35; PPE68mixand P19, P24 of PPE68 showed antibody reactivity with sera of mice immunized with the corresponding recombinant pUMVC6 and/or pUMVC7 DNA vaccine constructs. The results confirm in vivo expression and immunogenicity of all the five RD1 and RD9 genes cloned in both of the DNA vaccine vectors.