Helicobacter pylori gene silencing in vivo demonstrates urease is essential for chronic infection

PLoS Pathogens

Keith A. Stubbs¹  Alma Fulurija¹  Aleksandra W. Debowski¹  Binit Lamichhane¹  Robyn Himbeck¹  Alfred Chin-Yen Tay¹  Mohammed Benghezal²  Barry J. Marshall²  Senta M. Walton²  Tingting Liao²  Eng-Guan Chua³ 

[1] Helicobacter pylori Research Laboratory, Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Nedlands, Western Australia, Australia;Ondek Pty. Ltd., Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, University of Western Australia, Nedlands, Western Australia, Australia;School of Molecular Sciences, University of Western Australia, Crawley, Western Australia, Australia

关键词: Ureases;    Helicobacter pylori;    Urea;    Stomach;    Tetracyclines;    Polymerase chain reaction;    Gastrointestinal infections;    Helicobacter pylori infection;   

DOI  :  10.1371/journal.ppat.1006464

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Helicobacter pylori infection causes chronic active gastritis that after many years of infection can develop into peptic ulceration or gastric adenocarcinoma. The bacterium is highly adapted to surviving in the gastric environment and a key adaptation is the virulence factor urease. Although widely postulated, the requirement of urease expression for persistent infection has not been elucidated experimentally as conventional urease knockout mutants are incapable of colonization. To overcome this constraint, conditional H. pylori urease mutants were constructed by adapting the tetracycline inducible expression system that enabled changing the urease phenotype of the bacteria during established infection. Through tight regulation we demonstrate that urease expression is not only required for establishing initial colonization but also for maintaining chronic infection. Furthermore, successful isolation of tet-escape mutants from a late infection time point revealed the strong selective pressure on this gastric pathogen to continuously express urease in order to maintain chronic infection. In addition to mutations in the conditional gene expression system, escape mutants were found to harbor changes in other genes including the alternative RNA polymerase sigma factor, fliA, highlighting the genetic plasticity of H. pylori to adapt to a changing niche. The tet-system described here opens up opportunities to studying genes involved in the chronic stage of H. pylori infection to gain insight into bacterial mechanisms promoting immune escape and life-long infection. Furthermore, this genetic tool also allows for a new avenue of inquiry into understanding the importance of various virulence determinants in a changing biological environment when the bacterium is put under duress.

【 授权许可】

CC BY