Effects of Cytokine IL-18 Gene on Antibody Production Induced by Ag85A DNA Vaccine

CHEN Hai-wen; WANG Zi-Ming; FAN Xiong-lin; GAN Wei-min; Shi Tao; XU Zhi-kai; LI Yuan

Abstract：Objective: To investigate the effects of plasmid containing human IL-18 gene on the humoral immune response of mice immunized by Ag85A DNA vaccines of Mycobacterium tuberculosis H37 Rv strain. Methods:Human IL-18 cDNA was amplified from RNA of peripheral blood mononuclear cells(PBMCs )by RT- PCR and cloned into the pGEM-TEasy vector. After sequencing IL-18 gene was subcloned into the the sites of Bam H I and EcoR Ⅰ digestion of pcDNA3.1. BALB/c mice were injected intramuscularly with eukaryotic expression plasmid pcIL18, together with MTB pcAg85A DNA vaccines. The same immunization was repeated three times at intervals of two weeks. Mouse sera were collected at two weeks after the each injection. The titers of anti-Ag85A antibody were detected by ELISA.Results:IL-18 cDNA was amplified successfully from RNA of human PBMCs by RT-PCR and the result of sequencing was correct. The H-18 gene was correctly inserted into the vector pcDNA3.1, which was confirmed with BamH I and EcoR I digestion analysis. The positive plasmid was called pcIL18.After being immunized with DNA vaccines,the titers of antibody obtained from mice being immunized by pcAg85A combining with pcIL18 were superior to mice immunanized by pcAg85A independently. Conclusion: Combination of IL-18 gene with MTB pcAg85A DNA vaccine could observably enhance the humoral immune responses to pcAg85A. It remains further investigated whether IL-18 gene plus MTB pcAg85A DNA vaccine could markedly induce the cellular mediated immune response to Ag85A or not.