Laboratorio de Genética Molecular Dr. Jorge Yunis-Turbay, Decanato de Ciencias de la Salud, Universidad Centroccidental Lisandro Alvarado (UCLA), Barquisimeto, Venezuela.
Int J Infect Dis. 2013 Sep;17(9):e750-6. doi: 10.1016/j.ijid.2013.03.004. Epub 2013 Apr 20.
Helicobacter pylori is a major cause of chronic gastritis and an established risk factor for gastric adenocarcinoma. This bacterium also exhibits an extraordinarily high genetic diversity.
The genetic diversity of H. pylori strains from Venezuelan patients with chronic gastritis was evaluated by PCR-typing of vacA, cagA, iceA, and babA2 virulence-associated genes using DNA extracted directly from biopsies. The nucleotide sequence and prevalence of size variants of iceA1, iceA2, and babA2 PCR products were introduced in this analysis.
The frequency of vacA s1 was associated (p<0.01) with moderate/severe grades of atrophic gastritis. The cagA, iceA1, iceA2, and babA2 genotypes were found in 70.6%, 66.4%, 33.6%, and 92.3% of strains, respectively. The frequency of iceA2 and its subtype iceA2_D were higher (p<0.015) in cases with moderate/severe granulocytic inflammation. The most prevalent combined genotypes were vacA s1m1/cagA/iceA1/babA2 (26.3%), vacA s2m2/iceA1/babA2 (19.5%), and vacA s1m1/cagA/iceA2/babA2 (18.8%). Sequence analysis of iceA1, iceA2, and babA2 PCR-amplified fragments allowed us to define allelic variants and to increase the number of genotypes detected (from 19 to 62). A phylogenetic tree made with iceA1 sequences showed that the H. pylori strains analyzed here were grouped with those of Western origin.
Our results show that patients from the western region of Venezuela have an elevated prevalence of infection with H. pylori strains carrying known virulence genotypes with high genetic diversity. This highlights the importance of identifying gene variants for an early detection of virulent genotypes.
幽门螺杆菌是慢性胃炎的主要病因，也是胃腺癌的既定危险因素。这种细菌还表现出极高的遗传多样性。
使用直接从活检中提取的 DNA，通过 PCR 对 vacA、cagA、iceA 和 babA2 毒力相关基因对委内瑞拉慢性胃炎患者的 H. pylori 菌株的遗传多样性进行评估。在本分析中引入了 iceA1、iceA2 和 babA2 PCR 产物的核苷酸序列和大小变异型的流行率。
vacA s1 的频率与中重度萎缩性胃炎相关（p<0.01）。cagA、iceA1、iceA2 和 babA2 基因型分别在 70.6%、66.4%、33.6%和 92.3%的菌株中发现。中度/重度粒细胞性炎症病例中 iceA2 及其亚型 iceA2_D 的频率更高（p<0.015）。最常见的组合基因型是 vacA s1m1/cagA/iceA1/babA2（26.3%）、vacA s2m2/iceA1/babA2（19.5%）和 vacA s1m1/cagA/iceA2/babA2（18.8%）。iceA1、iceA2 和 babA2 PCR 扩增片段的序列分析使我们能够定义等位基因变体并增加检测到的基因型数量（从 19 个增加到 62 个）。使用 iceA1 序列构建的系统发育树表明，在此分析的 H. pylori 菌株与西方起源的菌株聚集在一起。
我们的结果表明，来自委内瑞拉西部地区的患者感染携带高遗传多样性的已知毒力基因型的 H. pylori 菌株的流行率较高。这强调了识别基因变异体以早期检测毒力基因型的重要性。
