[Dimo-Thylidioctyl Ammonium Bromide-Bcg Polysaccharide Nucleic Acid Adjuvant Enhanced the Immunogenicity of a Mycobacterium Tuberculosis Subunit Vaccine].

OBJECTIVE:To investigate the activity of a novel adjuvant consisting of dimethyldioctyldecyl ammonium bromide (DDA) and BCG polysaccharide nucleic acid (BCG-PSN).METHODS:BCG-PSN was extracted by hot-phenol method, and combined with DDA and Mycobacterium tuberculosis fusion antigen AMM (Ag85B-MPT64(190-198)-Mtb8.4) to formulate the Mycobacterium tuberculosis subunit vaccine. Mice were immunized subcutaneously with a 2-week interval between the immunizations (0.2 ml/dose), and humoral and cell-mediated immunity were detected by ELISA and ELISPOT respectively.RESULTS:With the stimulation of Ag85B in vitro, the number of antigen specific IFN-gamma producing spleen lymphocytes were 222 +/- 79, 259 +/- 85, 230 +/- 64 per million respectively in the mice immunized with AMM + DDA + BCG-PSN, AMM + DDA, and BCG. Spleen lymphocytes in these 3 groups produced higher levels of IFN-gamma compared to the groups with the adjuvant of IFA or BCG-PSN alone or without adjuvant upon stimulation with Ag85B (t = 2.923-7.118, P < 0.05). Furthermore, the adjuvant consisting of DDA and BCG-PSN increased the ratio of Ig(2a)/IgG1 than DDA alone (0.125 vs. 0.025). Combined with AMM, the adjuvant DDA and the one consisting of DDA and BCG-PSN induced higher level of immunity than incomplete Freund's adjuvant (IFA), NaCl, and BCG-PSN alone.CONCLUSION:Mycobacterium tuberculosis subunit vaccine AMM + DDA + BCG-PSN induced a strong Th1-type immune response, and DDA + BCG-PSN, especially DDA promoted the immune response of the M. tuberculosis subunit vaccine in mice.