Differences in genotypes of Helicobacter pylori from different human populations

DNA motifs at several informative loci in more than 500 strains of Helicoba cter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deleti on, insertion, and substitution motifs were found at the right end of the H . pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. resident s; type II predominated among Japanese and Chinese; and type III predominat ed in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Per uvians were also more like those from Spaniards than those from Asians. The se indications of relatedness of Latin American and Spanish strains, despit e the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World b y European conquerors and colonists about. 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in pe ople quite recently in human evolution.