Malfertheiner P et al. (2008) Safety and immunogenicity of an intramuscular Helicobacter pylori vaccine in noninfected volunteers: a phase I study. Gastroenterology 135: 787–795

Studies in animal models have shown that vaccination with recombinant Helicobacter pylori vacuolating cytotoxin A (VacA), cytotoxin-associated antigen, and neutrophil-activating protein (NAP) confers protection against H. pylori infection. Malfertheiner et al. have now shown that a prophylactic vaccine comprising these three conserved antigens plus an aluminum hydroxide adjuvant is safe and exhibits strong immunogenicity in H. pylori-negative individuals.

In this phase I, single-blind study, healthy volunteers aged 18–40 years were randomly assigned to receive intramuscular vaccine or placebo in one of two monthly vaccination schedules (0, 1 and 2 months or 0, 1 and 4 months; n = 38) or to receive vaccine in a weekly schedule (0, 1 and 2 weeks; n = 19). The incidence of local and systemic adverse effects within 6 days of injection was similar in the monthly vaccine groups and the placebo group.

Following the three scheduled vaccinations, all vaccinated individuals responded at both the antibody and T-cell levels to a least one of the antigens (mainly VacA and NAP); 86% of vaccinated participants responded to all three antigens. All 36 individuals who received a fourth booster dose of vaccine 18–24 months after completion of primary vaccination showed a strong anamnestic antibody and cellular response to the vaccine.

The authors conclude that the recombinant three-antigen H. pylori vaccine has acceptable safety and immunogenicity, and stimulates antigen-specific T-cell memory, and thus warrants further clinical study.