Vaccine strategies for prevention of Helicobacter pylori infection.

OBJECTIVE

To examine the level and duration of the humoral immune response to Helicobacter felis following oral immunization or infection.

DESIGN AND METHODS

Germ-free mice were orally immunized with sonicated 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 were killed at 3-week intervals and serum, gastric washings, intestinal washings and gastric biopsies were obtained. H. felis infection was confirmed by a positive urease test or culture of the gastric biopsy. Serum gastric and intestinal antibody titers were determined by enzyme-linked immunosorbent assay.

CONCLUSION

Infection and immunization against H. felis produces a specific humoral response. The humoral response in infection alone is significantly smaller than that of immunized animals until 6 weeks after infection. The humoral response following oral immunization persists for at least 18 weeks without further stimulation. The presence of an H. felis-specific antibody immune response before infection may be needed to protect animals from acute Helicobacter infection.