New York University School of Medicine, New York, New York 10010, USA.
J Clin Microbiol. 2010 Mar;48(3):690-6. doi: 10.1128/JCM.01815-09. Epub 2010 Jan 6.
Helicobacter pylori is known to be a major cause of gastric carcinoma and peptic ulceration. cagA positivity and vacA's signal regions and mid-regions are well-characterized markers of H. pylori's virulence. Recently, an intermediate region has been identified as another strong marker of H. pylori-associated disease, and its i1 allele has been linked with severe diseases in colonized hosts. The goal of this study was to determine the prevalence of the intermediate alleles in H. pylori isolates from China, Turkey, and Uruguay and from U.S. Africans and to compare their distribution with other well-characterized virulence factors. Originally, 123 H. pylori strains were studied, but 3 were excluded due to the failure to amplify the intermediate region in these samples. Therefore, a total of 120 strains were analyzed: 30 Chinese isolates, 35 Turkish isolates, 30 Uruguayan isolates, and 25 U.S. African isolates. The s type and the m type were determined by PCR amplification. The i type was identified by PCR amplification and DNA sequencing. CagA status was determined by PCR methodology. There was a strong correlation among CagA positivity, s1, and i1 in Chinese, U.S. African, and Uruguayan isolates, but less correlation among these markers in Turkish isolates. A new intermediate variant (i3) was identified in 25.7% of Turkish strains and 3.3% of the Chinese strains. In summary, the distribution of CagA positivity and s1 correlated with the i1 in the three populations, except in the Turkish population, which showed a disproportionate representation of the i3 allele. Phylogenetic mapping confirmed the i-typing method previously defined and adopted for this study. The phylogenetic tree showed country-specific correlation with the intermediate region. Our results showed that the i1 allele is strongly associated with CagA positivity and the vacA s1 allele, suggesting its role as a virulence marker and potential predictor for clinical outcome.
幽门螺杆菌是导致胃癌和消化性溃疡的主要原因。cagA 阳性和 vacA 的信号区和中间区是幽门螺杆菌毒力的特征性标志物。最近，一个中间区被确定为另一个与幽门螺杆菌相关疾病的强标志物，其 i1 等位基因与定植宿主的严重疾病有关。本研究的目的是确定中国、土耳其、乌拉圭和美国非洲裔人群中幽门螺杆菌分离株的中间等位基因的流行率，并将其分布与其他特征明确的毒力因子进行比较。最初研究了 123 株幽门螺杆菌，但由于这 3 株样本中无法扩增中间区，因此排除了 3 株。因此，共分析了 120 株菌株：30 株中国分离株、35 株土耳其分离株、30 株乌拉圭分离株和 25 株美国非洲裔分离株。s 型和 m 型通过 PCR 扩增确定。i 型通过 PCR 扩增和 DNA 测序确定。CagA 状态通过 PCR 方法确定。在中国、美国非洲裔和乌拉圭分离株中，CagA 阳性、s1 和 i1 之间存在很强的相关性，但在土耳其分离株中这些标志物之间的相关性较弱。在 25.7%的土耳其菌株和 3.3%的中国菌株中发现了一种新的中间变体（i3）。总之，除了土耳其人群中外，CagA 阳性和 s1 的分布与三种人群中的 i1 相关，土耳其人群中 i3 等位基因的比例不成比例。系统发育映射证实了本研究中先前定义并采用的 i 型分型方法。系统发育树显示与中间区具有特定国家的相关性。我们的结果表明，i1 等位基因与 CagA 阳性和 vacA s1 等位基因密切相关，提示其作为毒力标志物和临床结果的潜在预测因子的作用。
