Variations in the gene for vacuolating toxin, vacA, in Japanese isolates of Helicobacter pylori.

Each of 284 strains of Helicobacter pylori which had been isolated in Japan was shown, by use of the polymerase chain reaction (PCR), to be positive for the vacA genes. The amplified vacA genes generated by PCR were classified into six classes (five for the clinical isolates, and one which corresponded to the standard strains). Endoscopic analysis revealed that cases of gastritis were most likely to be associated with class D, while none were associated with class A. The patterns of products of PCR obtained from the Japanese isolates were compared with theoretical patterns derived from sequences of vacA which had been reported previously. The nucleotide sequences of amplified fragments of vacA from representative strains in each class were determined and compared with those of previously reported vacA genes.