中国幽门螺杆菌vacA基因的等位变异

目的 明确中国幽门螺杆菌（Ｈｅｌｉｃｏｂａｃｔｅｒ ｐｙｌｏｒｉ，Ｈｐ）全长ｖａｃＡ基因的等位变异及其与西方主要菌株基因序列的差异。方法 从５例胃病患者胃黏膜粘栓组织中分离培养２２个单个Ｈｐ克隆，以Ｗｅｓｔｅｒｍ ｂｌｏｔ确定ｖａｃＡ表型特点，以体外细胞毒性试验研究其活性。然后选择５株有代表性的克隆进行基因组ＤＮＡ抽提、ＰＣＲ扩增及ｖａｃＡ基因全序列测定、分析。结果 ５株中４株ｖａｃＡ表达阳性。只

Allelic variation in the vacA gene of Helicobacter pylori isolated from China

Objective To characterize the vacA alleles that tare present in Chinese H. pylori group and compare the allelic variation in the vacA gene with the Western strains. Methods 22 single colonies of H. py-lori isolated from 5 biopsies with different gastric disorders were characterized for expression of VacA protein and for evaluating the cytotoxic activity in HeLa cell. Five representative strains were selected and the vacA gene was amplified by PCR and subjected to automatic DNA sequencing using a primer walking strategy.Results Four strains expressed VacA protein. Only one of the five strains induced the vacuoles in HeLa cell.All the five vacA gene coded for identical signal peptides of the sla allele and an eight amino acids represent at the reported proteolytic cleavage site. One of the five strains expressed a VacA protein with a middle region most similar to the ml allele and the others to the m2 allele. The four m2 allele strains had few vacuolating ac-tivity in HeLa cell. The phylogenetic analysis indicate that the homologues of same type Chinese vacA genes were 97.6% ～99.2% compared with those 91.3% ～92.0% of the Western strains. Conclusions There are allelic variations of vacA gene between Chinese H. pylori and the Western' s. It forms phylogenetically a inde-pendent cluster. The type m2 strains seem to be more prevalent in China. The cytotoxicity in HeLa cell appears to associate with the middle region but not signal sequence.