flaA mRNA transcription level correlates with Helicobacter pylori colonisation efficiency in gnotobiotic piglets

In-vivo passage of the gastric pathogen Helicobacter pylori in gnotobiotic piglets results in a greater colonisation efficiency in subsequent infectio ns. The rate of colonisation steadily increases with the number of passages . To determine if this increased efficiency is related to the level of expr ession of flaA, a gene which encodes the major subunit of flagella, this st udy evaluated the level of flaA expression at five points during serial in- vivo passage of strain 26695. Semi-quantitative reverse transcriptase polym erase chain reaction and Northern dot-blot analysis of flaA mRNA levels (ex pressed as a ratio to the level of ureA mRNA) revealed a positive correlati on between flaA expression and colonisation efficiency; flaA mRNA levels in creased incrementally with in-vivo passage as did colonisation rates. Immun oblots of outer-membrane vesicles from pig-passaged and laboratory-passaged strains also demonstrated marked differences in the amount of flagellin pr esent in poor and efficient colonisers.