VACCINATION OF GNOTOBIOTIC PIGLETS AGAINST HELICOBACTER-PYLORI

To determine the effect of oral adjuvant-assisted and parenteral vacci nation, germ-free piglets were vaccinated orally with and without labi le toxin adjuvant or parenterally and challenged with viable Helicobac ter pylori, All prechallenge vaccination regimens induced anti-H. pylo ri antibodies and suppressed bacterial colonization, but no vaccinatio n regime completely prevented infection. Parenteral vaccination given after infection had no effect on bacterial colonization. Lymphocytic g astritis was present in all piglets challenged with live bacteria rega rdless of vaccination status. Neutrophilic gastritis was present in va ccinated challenged piglets but not in infected, unvaccinated piglets. Gastritis was not present in uninfected control piglets regardless of vaccination status. In gnotobiotic piglets, vaccination suppresses bu t does not prevent infection by H. pylori, and parenteral vaccination does not cure infected piglets. Vaccination does not ameliorate gastri tis due to H. pylori in piglets but does induce neutrophilic gastric i nflammation in some infected piglets.