多重聚合酶链反应鉴定幽门螺杆菌基因型

Multiplex PC R in the determination of H. Pylori cagA and vacA genotypes

AIM To establish a multiplex polymerase chain reaction(PCR) method for determination of Helicobacter pylori (H. pylori ) cagA, vacA genotypes and to type cagA, vacA genotypes of 90 H. pylori isolates. METHODS In single PCR tube, 2-4 specific DNA bands were concurrently amplified with 7 primers (primers P1 and P2 for cagA gene, primers VAG-F, VAG-R, VA1-F, VA1-R and SS1-F for vacA genotypes). According to specific products, H. pylori cagA and vacA genotypes were dertermined. RESULTS A multiplex PCR method was established to dertermin H. pylori cagA, vacA genotypes. The sensitivity of this system was about 300CFU. Of 90 H. pylori isolates, 82 (91.1%) were cagA positive. H. pylori strains of s1a, s1b and s2 vacA genotypes were 46 (51.1% ), 36(40.0% ) and 8(8.9% ) respectively. H. pylori strains of m1 and m2 types were 46(51.1%) and 44(48.9%). In total, 96.3% of type vacA s1 H. pylori strains and 25.0% of type vacA s2 H. pylori strains were cagA positive ( X~2 = 38.39, P<0.001 ). CONCLUSION This multiplex PCR system is a highly specific, rapid, simple and economical method. H. pylori strains from Xi'an area were almost cagA positive. Thepresense of the cagA gene was closely associated with type vacA s1 (especially type s1a) gene of H. pylori strain.