Then insert the fusion gene CTB-ureB into the vector pUC19. The recombinant plasmid was identified with PCR and enzyme digestion, and was confirmed by sequence analyze.

• CTB、ureB基因的融合及克隆：采用高保真PCR技术，分别从质粒pGEM-CTB和幽门螺杆菌基因组DNA中扩增出CTB和cagA基因，然后通过PCR法融合两个基因，最后将CTB-ureB融合基因插入载体pUC19，PCR筛选、酶切鉴定阳性克隆，进行DNA序列分析验证。