Host specificity of Helicobacter pylori strains and host responses in experimentally challenged nonhuman primates

Background & Aims: The specificity of colonization by Helicobacter pylori and complex host-bacterium interactions cannot be readily examined in humans. The aim of this study was to perform such analyses in rhesus monkeys. Methods: Four animals that had been cured of natural H, pylori colonization were challenged with a mixture of 7 strains of human origin, and bacteria recovered during periodic videogastroscopy were DNA fingerprinted. Results: Three animals carried mixtures of several strains for 4 months, after which strain J166 predominated. In the fourth animal, only strain J238 was isolated from the earliest phase of colonization through 7 months, but strain J166 again became predominant by 10 months after the challenge, Gastritis scores and plasma gastrin and anti-H, pylori immunoglobulin G titers reached levels observed in naturally colonized animals by 4 months after the challenge; however, no plasma immunoglobulin A response was observed up to 10 months. Conclusions: These results show that (1) natural colonization does not elicit protective immunity against subsequent H. pylori challenge; (2) individuals differ in susceptibility to different H. pylori strains during initial stages of colonization; and (3) certain strains are better suited than others for long-term survival in different hosts. These observations show the complexity of H. pylori-host interactions.