Application of vacA Sequencing in Helicobacter pylori for Classification of Specimens from Healthy Persons, and from Hepatobiliary and Gastroduodenal Patients

Helicobacter pylori is an important causative agent of gastrointestinal and hepatobiliary diseases. The aim of this study was to investigate phylogenetic relationships among H. pylori strains from the oral cavities of healthy individuals, gastric biopsies from gastroduodenal (GI) patients and bile samples from hepatobiliary (HB) patients in the northeast of Thailand. The DNA sequences of a portion of the vacuolating cytotoxin A gene (vacA) were investigated. Phylogenetic trees were constructed using the neighbor-joining and maximum-likelihood methods. The vacA sequences of H. pylori fell into four main groups on the trees. Strains from healthy persons fell into two widely separated but well-supported groups, while most H. pylori vacA sequences from HB patients were distributed in another two groups. In contrast, the H. pylori strains from GI patients were scattered across the tree, without a clear geographical pattern. In conclusion, the sequence of vacA may be useful to classify the genetic relationship of H. pylori derived from different sources.