| Theme | Molecular Biology & GI Tract | |
|---|---|---|
| Title | Molecular Analysis of Gastic Mucosal Injury Caused by Helicobacter pylori Infection | |
| Publish Date | 1997/06 | |
| Author | Tadashi Kodama | Third Department of Internal Medicine, Kyoto Prefectural University of Medicine |
| Author | Yoshio Yamaoka | Third Department of Internal Medicine, Kyoto Prefectural University of Medicine |
| [ Summary ] | It has been thought that vacuolating cytotoxin-positive and -negative Helicobacter pylori (H. pylori) strains differed substantially in terms of the sequences of the vacA gene. Recently, Atherton et al. reported the existence of three distinct families of vacA signal sequences (s1a, s1b and s2) and two distinct families of middle-region alleles (m1 and m2). Furthermore, type sl/ml strains were shown to produce higher cytotoxin activity levels than type s1/m2 strains, while none of the type s2/m2 strains procduced detectable cytotoxin activity. However, most strains in Japan showed the s1a pattern regardless of disease. Virtually none of the strains could be assigned to either the m1 or the m2 pattern. When the middle region of the vacA gene was analyzed by the PCR-direct sequences method, however, most strains showed sequences similar to the m1 pattern. The cagA genes are thought to represent other H. pylori virulence factors. Most strains in Japan, however, possess the cagA gene and most patients infected with cagA gene-positive strains show gastritis. Therefore, H. pylori in Japan differs markedly from H. pylori in Europe and the United States, suggesting that the vacA and cagA genes may not be ulcerogenic factors. However, our findings do suggest the possibility of mutations in repeated DNA sequences of the cagA gene in gastric cancer cases. |
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