Basic Research
Copyright ©The Author(s) 2003. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 15, 2003; 9(12): 2720-2725
Published online Dec 15, 2003. doi: 10.3748/wjg.v9.i12.2720
Identification of alkA gene related to virulence of Shigella flexneri 2a by mutational analysis
Zhao-Xing Shi, Heng-Liang Wang, Kun Hu, Er-Ling Feng, Xiao Yao, Guo-Fu Su, Pei-Tang Huang, Liu-Yu Huang
Zhao-Xing Shi, Heng-Liang Wang, Kun Hu, Er-Ling Feng, Guo-Fu Su, Pei-Tang Huang, Liu-Yu Huang, Beijing Institute of Biotechnology, Beijing 100071, China
Xiao Yao, College of Environmental and Chemical Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi Province, China
Author contributions: All authors contributed equally to the work.
Supported by the Major State Basic Research Development Program of China (973 Program), No. G1999054103; National High-technology Research and Development Program of China (863 Program), No. 2001AA215211; and Capital “248” Key Innovation Program of China, No. H010210360119
Correspondence to: Liu-Yu Huang, Beijing Institute of Biotechnology, 20 East Fengtai Street, Beijing 100071, China. huangly@nic.bmi.ac.cn
Telephone: +86-10-66948805 Fax: +86-10-63833521
Received: July 17, 2003
Revised: July 24, 2003
Accepted: July 30, 2003
Published online: December 15, 2003
Abstract

AIM: In vivo induced genes are thought to play an important role during infection of host. AlkA was identified as an in vivo-induced gene by in vivo expression technology (IVET), but its virulence in Shigella flexneri was not reported. The purpose of this study was to identify the role of alkA gene in the pathogenesis of S. flexneri.

METHODS: PCR was used to amplify alkA gene of S. flexneri 2a and fragment 028pKm. The fragment was then transformed into 2457T05 strain, a S flexneri 2a strain containing Red recombination system, which was constructed with a recombinant suicide plasmid pXLkd46. By in vivo homologous recombination, alkA mutants were obtained and verified by PCR and sequencing. Intracellular survival assay and virulence assay were used to test the intracellular survival ability in HeLa cell model and the virulence in mice lung infection model respectively.

RESULTS: Deletion mutant of S. flexneri 2a alkA was successfully constructed by λ Red recombination system. The mutant exhibited significant survival defects and much significant virulence defects in mice infection assay.

CONCLUSION: AlkA gene plays an important role in the infection of epithelial cells and is a virulent gene of Shigella spp.

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