Helicobacter pylori heat shock protein A: Serologic responses and genetic diversity

Helicobacter pylori synthesizes an unusual GroES homolog, heat shock protei n A (HspA). The present study was aimed at an assessment of the serological response to HspA in a group of Chinese patients with defined gastroduodena l pathologies and determination of whether diversity is present in the nucl eotide sequences encoding HspA in isolates from these patients. Serum sampl es collected from 154 patients who had an upper gastrointestinal pathology and the presence of H. pylori defined by biopsy were tested for an immunogl obulin G (IgG) serologic response to H. pylori HspA by an enzyme linked imm unosorbant assay. HspA-encoding nucleotide sequences in H. pylori isolates from 14 patients (7 seropositive and 7 seronegative for HspA) were analyzed by PCR and direct sequencing of the PCR products. The sequencing results w ere compared to those of 48 isolates from other parts of the world. Of the 154 known H, pylori-positive patients, 54 (35.1%) were seropositive for Hsp A. The A domain (GroES homology) of HspA was highly conserved in the 14 iso lates tested. Although the B-domain (metal-binding site unique to H. pylori ) resembled that in the known major variant, particular amino acid substitu tions allowed definition of an HspA variant associated with isolates from E ast Asia. There were no associations between patient characteristics and Hs pA seropositivity or amino acid sequences. We confirmed in this study that the clinical outcomes of H. pylori infection are not related to HspA antige nicity or to sequence variation. However, B-domain sequence variation may b e a marker for the study of the genetic diversity of H. pylori strains of d ifferent geographic origins.