H pylori
Copyright ©2006 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Jul 7, 2006; 12(25): 3989-3993
Published online Jul 7, 2006. doi: 10.3748/wjg.v12.i25.3989
Characterization of flgK gene and FlgK protein required for H pylori Colonization-from cloning to clinical relevance
Jiunn-Jong Wu, Bor-Shyang Sheu, Ay-Huey Huang, Shin-Ting Lin, Hsiao-Bai Yang
Jiunn-Jong Wu, Departments of Medical Technology, National Cheng Kung University Hospital, 138 Sheng Li Road, Tainan 70428, Taiwan, China
Bor-Shyang Sheu, Department of Internal Medicine, National Cheng Kung University Hospital, 138 Sheng Li Road, Tainan 70428, Taiwan, China
Ay-Huey Huang, Hsiao-Bai Yang, Departments of Pathology, National Cheng Kung University Hospital, 138 Sheng Li Road, Tainan 70428, Taiwan, China
Shin-Ting Lin, Institutes of Microbiology and and immunity, National Cheng Kung University Hospital, 138 Sheng Li Road, Tainan 70428, Taiwan, China
Author contributions: All authors contributed equally to the work.
Supported by grants from National Science Council, Taiwan No. NSC93-2316-B-006-011 and NSC91-2320-B-006-091
Correspondence to: Professor Bor-Shyang Sheu, Department of Internal Medicine, National Cheng Kung University Hospital, 138 Sheng Li Road, Tainan 70428, Taiwan, China. sheubs@mail.ncku.edu.tw
Telephone: +886-6-2353535-5368 Fax: +886-6-2370941
Received: June 3, 2005
Revised: June 14, 2005
Accepted: June 24, 2005
Published online: July 7, 2006
Abstract

AIM: To characterize the role of flgK and its protein product in H pylori colonization.

METHODS: The PCR cloning method identified the flgK gene. An isogenic flgK mutant was constructed by gene replacement and confirmed by Southern blot analysis and PCR analysis. The recombinant FlgK protein (r-FlgK) was purified. Electron microscopy (EM) was applied to demonstrate the flagella of H pylori. An in vitro motility test was assessed in semisolid medium. The densities of H pylori colonization with either the wild-type strain or its flgK mutant were compared among BALB/c mice with or without pre-immunization with r-FlgK. The serological responses to r-FlgK were analyzed for 70 clinical patients with different densities of H pylori colonization.

RESULTS: From a duodenal ulcer strain, the flgK gene was cloned and it contained 1821 bp, with a 95.7% identity to the published sequences. No flagella were observed under EM for the mutant strain, which had a loss of motility. H pylori density was lower in the BALB/c mice inoculated by the mutant or with pre-immunization with r-FlgK compared to unimmunized mice or mice inoculated by the wild-type strain (P < 0.05). In the H pylori-infected patients, the serological responses to r-FlgK were uniformly low in titer.

CONCLUSION: FlgK encoded by flgK is important for flagella formation and H pylori motility. Deficiency in FlgK or an enhanced serological response to r-FlgK can interfere with H pylori colonization. FlgK of H pylori could be a novel target for vaccination.

Keywords: H pylori; Colonization; Isogenic mutant; BALB/c mice; Flagella; Vaccine.