VACCINE STRATEGIES FOR PREVENTION OF HELICOBACTER-PYLORI INFECTION

Objectives: To examine the level and duration of the humoral immune re sponse to Helicobacter felis following oral immunization or infection. Design and methods: Germ-free mice were orally immunized with sonicat ed H. felis plus cholera toxin five times over 6 weeks. One week after immunization was completed, immunized and control non-immunized mice received an oral challenge of live H. felis organisms. The animals wer e killed at 3-week intervals and serum, gastric washings, intestinal w ashings and gastric biopsies were obtained. H. felis infection was con firmed by a positive urease test or culture of the gastric biopsy. Ser um gastric and intestinal antibody titers were determined by enzyme-li nked immunosorbent assay. Conclusion: Infection and immunization again st H. felis produces a specific humoral response. The humoral response in infection alone is significantly smaller than that of immunized an imals until 6 weeks after infection. The humoral response following or al immunization persists for at least 18 weeks without further stimula tion. The presence of an H. felis-specific antibody immune response be fore infection may be needed to protect animals from acute Helicobacte r infection.