Suppressive effects of DNA vaccines encoding heat shock protein on Helicobacter pylori-induced gastritis in mice

We investigated the effect of DNA vaccines encoding H, pylori-heat shock pr otein A and B (pcDNA3.1-hspA and -hspB) on inducing immune responses agains t H, pylori in mice. C57BL/six mice aged 5 weeks were immunized by single i njection of 10 mug of pcDNA3.1-hspA and pcDNA3.1-hspB into intracutaneous t issue. Plasmid DNA lacking the inserted hsp were injected as a control. Thr ee months after vaccination, significant specific antibodies against H, pyl ori were detected by ELISA in the sera of vaccinated mice. Antibody isotype s were predominantly IgG2a (Th1-like) with pcDNA3.1-hspA and mixed IgG1/IgG 2a (Th0-like) with pcDNA3.1-hspB. DNA vaccination dramatically suppressed c olonies of bacteria in stomach of vaccinated mice (28,400 +/- 21,600/mm(2) for pcDNA3.1-hspA and 6800 +/- 3470/mm(2) for pcDNA3.1-hspB) compared to co ntrol mice (128,000 +/- 42,200/mm(2)). Histological analysis of the gastric mucosa demonstrated that the degree of gastritis was significantly lower i n the vaccinated mice than in control mice. These results demonstrated that DNA vaccines encoding H, pylori-Hsp induce significant immune response aga inst H. pylori to decrease gastric mucosal inflammation, indicating that a DNA vaccine can be a new approach against H, pylori in humans. (C) 2000 Aca demic Press.