一种新的幽门螺杆菌分类法──根据幽门螺杆菌毒力因子CagA和VacA的表达

ANALYSIS OF EXPRESSION OF CagA AND VacA VIRULENCE FACTORIN 43 STRAINS OF HELICOBACTER PYLORI REVEALS THAT CLINICAL ISOLATES CAN BE DIVIDED INTO TWO MAJOR TYPES AND THATCagA IS NOT NECESSARY FOR EXPRESSION OF THEVACUOLATING CYTOTOXIN

对４３个ＨＰ临床分离株，从分子水平对其基因特征和表型特性进行研究，结果显示，多数ＨＰ临床分离株可以归纳为二大类型。Ⅰ型细菌含有细胞毒素相关蛋白ＣａｇＡ基因，表达ＣａｇＡ蛋白和空泡毒素（ＶａｃＡ）蛋白；Ⅱ型细菌不含有ＣａｇＡ基因，不表达ＣａｇＡ蛋白和ＶａｃＡ蛋白。Ⅰ型和Ⅱ型细菌分别占５６％和１６％，而其余的２８％为中间表型，即仅表达其中的一个毒力因子，这一发现证明，尽管许多细胞毒性ＨＰ株含有ＣａｓＡ，但细胞毒素ＶａｃＡ的表达可以不需要ＣａｓＡ的存在。

Colonization of the mucosa of the stomach and the duodenum by Helicobacter pylori is the major cause of acute and chronic gastroduodenal pathologies in humans.Duodenal ulcer formation strongly correlates with the expression of an antigen(CagA)that is usually coexpressed witn the vacuolating cytotoxin(VacA),a protein that causes ulceration in the stomach of mice.However,the relationship between these two virulence factors is unknown.Todefine whether CagA and VacA are coexpressed in all clinical isolates and their relationships,we collected 43 clinical isolates of H.pylori and studied their genetic and phenotypic properties.Based on this analysis,most of the strains could be classified into two major types.Type Ⅰbacteria had the gene coding for CagA and expressed the CagA protein and the vacuolating cytotoxin.Type Ⅱbacteria did not have the gene ceding for CagA and did not express either the CagA protein or the vacuolating cytotoxin.TypeⅠand type Ⅱbacteria represented 56%and 16%,respectively,of the 43 clinical isolates,while the remaining 28% had an intermediate phenotype,expressing CagA independently of VacA or vice versa.This finding shows that although it is present in most cytotoxic strains,CagA is not necessary for the expression of the vaculating Cytotoxin.