[Progress of molecular bacteriological studies on Helicobacter pylori].

To understand pathogenesis of H. pylori in stomach diseases including gastric cancer, molecular bacteriological studies are important. The studies are greatly advanced by information of the whole genome sequence of this bacterium in 1997. Various methods of gene manipulation to identify the genes involved in pathogenesis are now available such as transformation followed by construction of knockout mutants, complementation using H. pylori-E. coli shuttle vectors, random insertion mutagenesis, and RT-PCR or proteome analysis of in vivo-expressed genes. The molecular mechanism of persistent infection of H. pylori is discussed in light of recent findings on molecular mechanisms of bacterial attachment and colonization as well as on gastric physiology.