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

Background & Aims: The specificity of colonization by Helicobacter pylori a nd complex host-bacterium interactions cannot be readily examined in humans . The aim of this study was to perform such analyses in rhesus monkeys. Met hods: Four animals that had been cured of natural H, pylori colonization we re challenged with a mixture of 7 strains of human origin, and bacteria rec overed during periodic videogastroscopy were DNA fingerprinted. Results: Th ree animals carried mixtures of several strains for 4 months, after which s train J166 predominated. In the fourth animal, only strain J238 was isolate d from the earliest phase of colonization through 7 months, but strain J166 again became predominant by 10 months after the challenge, Gastritis score s and plasma gastrin and anti-H, pylori immunoglobulin G titers reached lev els 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 el icit protective immunity against subsequent H. pylori challenge; (2) indivi duals differ in susceptibility to different H. pylori strains during initia l stages of colonization; and (3) certain strains are better suited than ot hers for long-term survival in different hosts. These observations show the complexity of H. pylori-host interactions.