JCM Accepts, published online ahead of print on 21 October 2009

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J. Clin. Microbiol. doi:10.1128/JCM.00504-09
Copyright (c) 2009, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Diverse Characteristics of the cagA Gene of Helicobacter pylori Strains in Gastric Cancer and Peptic Ulcer Patients from Southern Vietnam

Bui Xuan Truong, Vo Thi Chi Mai, Hiroshi Tanaka, Le Thanh Ly, Tran Minh Thong, Hoang Hoa Hai, Dao Van Long, Keisuke Furumatsu, Masaru Yoshida, Hiromu Kutsumi, and Takeshi Azuma^*

Department of Gastroenterology, Bach Mai Hospital, Hanoi, Vietnam; Department of Microbiology, Cho Ray Hospital, Ho Chi Minh City, Vietnam; Department of Gastroenterology and Hepatology, Cho Ray Hospital, Ho Chi Minh City, Vietnam; Department of Pathology, Cho Ray Hospital, Ho Chi Minh City, Vietnam; Department of Scientific Study and Management, Cho Ray Hospital, Ho Chi Minh City, Vietnam; Department of Gastroenterology, Kobe University Graduate School of Medicine, Kobe, Japan

^* To whom correspondence should be addressed. Email: azumat{at}med.kobe-u.ac.jp.

The pathogenesis of gastro-duodenal diseases is related to the diversity of H. pylori strains. CagA-positive strains are more likely to cause gastric cancer than negative strains. Based on EPIYA motifs at the carboxyl terminus corresponding to phosphorylation sites, H. pylori CagA is divided into East Asian CagA and Western CagA. The former type prevails in East Asia and is more closely associated with gastric cancer. The present study used full sequences of the cagA gene and CagA protein of 22 H. pylori strains in gastric cancer and peptic ulcer patients from Southern Vietnam to make a comparison of genetic homology among Vietnamese strains and between them and other strains in East Asia. A phylogenetic tree was constructed based on full amino acid sequences of 22 Vietnamese strains in accordance with 54 references from around the world. The cagA gene was found in all Vietnamese H. pylori strains. 21 of 22 (95.5%) strains belonged to the East Asian type and had similar characteristics of amino acid sequence at the carboxyl terminus as other strains from the East Asian region. From evidence of East Asian CagA and epidemiologic cancerous lesions in Vietnam, H. pylori-infected Vietnamese can be classified into a high risk group for gastric cancer but further studies on the interaction among environmental and virulence factors should be done. Finally, phylogenetic data support that there is a Japanese sub-type in Western CagA type.