Helicobacter Pylori
Copyright ©2005 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 7, 2005; 11(21): 3255-3259
Published online Jun 7, 2005. doi: 10.3748/wjg.v11.i21.3255
Deletion of cagA gene of Helicobacter pylori by PCR products
Xun Zeng, Li-Hua He, Yan Yin, Mao-Jun Zhang, Jian-Zhong Zhang
Xun Zeng, Li-Hua He, Yan Yin, Mao-Jun Zhang, Jian-Zhong Zhang, Department of Diagnostics, National Institute of Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
Author contributions: All authors contributed equally to the work.
Correspondence to: Dr. Jian-Zhong Zhang, Department of Diagnostics, National Institute of Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, PO Box 5, Changping, Beijing 102206, China. zhangjianzhong@icdc.cn
Telephone: +86-10-6173-9456 Fax: +86-10-6173-9439
Received: December 28, 2004
Revised: December 29, 2004
Accepted: February 18, 2004
Published online: June 7, 2005
Abstract

AIM: Cytotoxin-associated protein (antigen) A (CagA) plays an important role in Helicobacter pylori (H pylori) pathogenesis. Our aim was to obtain cagA- mutant strains by a new mutation method so as to better understand the mechanism of CagA in epithelial cells.

METHODS: In contrast with the traditional method using suicide plasmid, we constructed cagA- mutant strains directly with PCR products. The constructed mutant clones grew on selective media and allelic exchange was confirmed by Southern blot. Furthermore, two different transformation methods, electroporation, and natural transformation, were compared with regard to the efficiency of recombination.

RESULTS: The mutation by PCR products could be completed within 3-5 d, and the recombination rate by electroporation and natural transformation was 4.02×10-8 and 1.03×10-9 respectively. Mutation rate by electroporation (4.02×10-8) was far higher than by natural transformation (1.03×10-9) (P = 0.000<0.005).

CONCLUSION: cagA- mutant strains have been constructed, which is important for further study on the function of CagA in epithelial cells. A mutation method by directly using PCR products has been proved successful with a much higher mutation rate, and is easier, especially when in combination with electroporation. This method could be widely used in gene deletion of H pylori.

Keywords: H pylori, CagA, Deletion