幽门螺杆菌vacA 基因表型与体外空泡毒性的关系

目的：研究不同vacA基因表型的幽门螺杆菌（HP）对HeLA细胞,RK－13细胞,SGC－7901细胞的空泡毒性作用,方法：分离培养30株临床胃粘膜标本中的HP菌株,抽提其总RNA和浓缩含空泡毒素（VacA)的培养上清,应用RT－PCR方法分析vacA基因表型,应用体外细胞空泡毒性试验观察其空泡毒性作用,结果：全部菌株的信号序列均为sla;vacA基因中区表型为m1型3株（10％）,m2型27株（90％）,m1型菌株对3种细胞均有空泡毒作用,m2型对HeLa细胞无空泡毒作用,但其中20株（（74％）对RK－13细胞,SGC7901细胞株有泡毒作用,结论：HP菌株vacA基因m区是与靶细胞结合的亚单位,不同m型菌株对同一种细胞产生不同的空泡毒性作用,表明靶细胞膜上可能存在不同的受体。

Relationship between Helicobacter pylori vacA genotype isolated from Chinese population and its vacuolating toxicity

Objective: To investigate vacuolating toxicity of vacA secreted by H.pylori with different vacA genotype isolated from Chinese on HeLa, RK 13 and SGC 7901 cells. Methods:The extraction of total RNA was performed by using Promega's SV total RNA isolation system according to manufacturer's instructions. The analysis of vacA genotype of H.pylori was done by RT PCR amplification. The vacuolating activity was observed on in vitro cell vacuolating assay. Results: All 30 clinical isolates were s1a type based on signal peptide sequences of vacA gene. Twenty seven of 30 clinical strains were m2 type and 3 isolates were m1 type on the bases of mid region of vacA gene. Strains with m1 form vacA induced vacuoles for HeLa, RK 13 and SGC 7901 cells. Isolates with m2 form vacA was unable to vacuolate HeLa cells, whereas 74% of them were toxic for RK 13 and SGC 7901 cells. Conclusion: Mid region of vacA gene encoding B subunit of vacA is a receptor binding and translocation moiety. H. pylori strains with different m type produce different toxic for same cell line, indicating there are different receptors on the surface of target cells.