Assessment of Helicobacter pylori gene expression within mouse and human gastric mucosae by real-time reverse transcriptase PCR

Despite increasing knowledge on the biology of Helicobacter pylori, little is known about the expression pattern of its genome during infection. While mouse models of infection have been widely used for the screening of prote ctive antigens, the reliability of the mouse model for gene expression anal ysis has not been assessed. In an attempt to address this question, we have developed a quantitative reverse transcriptase PCR (RT-PCR) that allowed t he detection of minute amounts of mRNA within the gastric mucosa. The expre ssion of four genes, 16S rRNA, ureA (encoding urease A subunit), katA (cata lase), and alpA (an adhesin), was monitored during the course of a 6-month infection of mice and in biopsy samples from of 15 infected humans. We foun d that the selected genes were all expressed within both mouse and human in fected mucosae. Moreover, the relative abundance of transcripts was the sam e (16S rRNA > ureA > katA > alpA), in the two models. Finally, results obta ined with the mouse model suggest a negative effect of bacterial burden on the number of transcripts of each gene expressed per CFU (P < 0.05 for 16S rRNA, alpA, and katA). Overall, this study demonstrates that real-time RT-P CR is a powerful tool for the detection and quantification of H. pylori gen e expression within the gastric mucosa and strongly indicates that mice exp erimentally infected with H. pylori provide a valuable model for the analys is of bacterial gene expression during infection.