Genome and Methylome Variation in Helicobacter pylori With a cag Pathogenicity Island During Early Stages of Human Infection

We analyzed adaptation of a fully virulent strain of H pylori to 12 different volunteers to obtain a robust estimate of the frequency of genetic and epigenetic changes in the absence of interstrain recombination. Our findings indicate that the large amount of genetic variation in H pylori poses a challenge to vaccine development. ClinicalTrials.gov no: NCT00736476.