Comparison of genomic structures and antigenic reactivities of orthologous29-kilodalton outer membrane proteins of Helicobacter pylori

We purified a 29-kDa Helicobacter pylori outer membrane protein (Omp29 prot ein) and cloned the gene encoding the protein from H. pylori strain ATCC 43 504. The Omp29 gene corresponded to the reported JHP73 and the HP78-79 gene s of H. pylori strains. A corresponding nucleotide fragment was detected in all 150 tested H. pylori clinical isolates by PCR or Southern blotting. Th e amplified Omp29-corresponding fragments were categorized into a ca. 770-b p-long group and a larger-fragment group. Sequence analysis indicated that the larger fragments were likely synthesized from the 770-bp fragments by i nsertion of an irrelevant fragment via 17-bp-long repeat sequences. Immunob lot analysis implies that the ca. 770-bp fragment is responsible for the pr otein homologous to Omp29, whereas the larger fragments are not responsible for those proteins or encoding antigenically distinct proteins. We postula te that the H. pylori outer membrane protein Omp29 can alter its antigenici ty through gene modifications mediated by nucleotide transfer.