| Autor: |
van Doorn, Leen-Jan, Figueiredo, Ce´u, Sanna, Ricardo, Blaser, Martin J., Quint, Wim G. V. |
| Zdroj: |
Journal of Clinical Microbiology; July 1999, Vol. 37 Issue: 7 p2306-2311, 6p |
| Abstrakt: |
ABSTRACTThe diversity of the cytotoxin-associated gene (cagA) of Helicobacter pyloriwas analyzed in 45 isolates obtained from nine countries. We examined variation in the 5' end of thecagAopen reading frame as determined by PCR and sequencing. Phylogenetic analysis revealed the existence of at least two distinct types of cagA. One variant (cagA1) was found exclusively in strains from Europe, the United States, and Australia, whereas a novel variant (cagA2) was found in strains from East Asia. The greatest diversity betweencagA1and cagA2was found in the first 20 amino acids of the cagAopen reading frame, where several consistent insertions or deletions were observed. AdditionalcagAsequence variants that could be classified as separate subtypes were found in two of three Peruvian and in five of seven U.S. strains tested. The calculated isoelectric point of the first 154 amino acids of the cagA1variants (7.52 ± 1.54) was significantly higher than that of the first 154 amino acids of thecagA2variants (5.61 ± 0.94; P< 0.001). Most cagA2strains contained vacAsubtype s1c (P< 0.001), and in vacAm1 strains cagA1was more frequently observed thancagA2. These results show the epidemiological relationship between cagAand vacAat the subtype level and indicate the existence of distinct H. pylorilineages that are not uniformly distributed over the globe. |
| Databáze: |
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