A team from Maryland, USA, investigated immunization as a strategy for preventing and treating H. pylori-associated disease.
The researchers assessed the safety and immunogenicity of a formalin-inactivated, oral H. pylori whole-cell (HWC) vaccine, in healthy adults. The vaccine was administered either with or without mutant Escherichia coli heat-labile toxin (LTR192G) as a mucosal adjuvant.
A dose-response study was conducted first of all. 23 subjects with or without H. pylori infection were vaccinated with either 2.5 × 106 HWC, 2.5 × 108 HWC, or 2.5 × 1010 HWC, plus 25 µg of LTR192G.
|The vaccine induced a significant rise in mucosal antibodies.|
|Infection and Immunity|
Thereafter, a randomized study was conducted in which 18 H. pylori-infected subjects were assigned, in a double-blind fashion, to receive one of four regimens. These were 2.5 × 1010 HWC plus placebo-adjuvant, placebo-vaccine plus 25 µg of LTR192G, placebo-vaccine plus placebo-adjuvant, or 2.5 × 1010 HWC plus 25 µg of LTR192G.
Diarrhea (6 subjects), low-grade fever (5 subjects), and vomiting (2 subjects) were observed, usually after the first dose.
Significant rises in geometric mean mucosal (fecal and salivary) anti-HWC immunoglobulin A antibodies were found to occur among H. pylori-infected and uninfected subjects, following inoculation with 2.5 × 1010 HWC plus 25 µg of LTR192G.
Moreover, among H. pylori-negative volunteers, this regimen induced significant lymphoproliferative responses in 5 of 10 subjects. It also induced gamma interferon production responses to H. pylori sonicate in 7 of 10 subjects.
There was no evidence that vaccination eradicated H. pylori in infected volunteers.
Karen L. Kotloff, of the Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, concluded on behalf of her colleagues, "These results suggest that it is possible to stimulate mucosal and systemic immune responses in humans to H. pylori antigens, by using an HWC vaccine."