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致病性细菌产生许多对宿主细胞有直接或间接作用的毒素,而且这些毒素常常在微生物致病中起关键作用。沙门菌可感染机体导致多种疾病,本文首次报道了伤寒、甲型副伤寒沙门菌可表达一种与大肠埃希菌(简称大肠杆菌)ClyA有同源性的成孔毒素,并证明编码ClyA的基因位点在肠道沙门菌不同血清型中是保守的,但在鼠伤寒沙门菌中则缺失。DNA序列分析发现肠道沙门菌血清型S2369/96和CT18的clyA样开放阅读框架与伤寒沙门菌Ty21a株的clyA编码序列有100%同源性,与clyA_(EC)的核苷酸序列有87%的同源性。甲型副伤寒沙门菌S3068/99的clyA_(SPa)序列与ClyA_(STy)及clyA_(EC)分别有98%和86%的同源性。ClyA_(SPa)和ClyA_(STy)是clyA基因的两个产物,两者与大肠杆菌的细胞溶素(A(ClyA_(EC))的氨基酸序列的同源性分别为91%及90%。扩增此两基因并分别克隆形成重组体Ty21a/
Pathogenic bacteria produce many toxins that act directly or indirectly on host cells, and these toxins often play a key role in microbial pathogenesis. Salmonella can infect the body leading to a variety of diseases. The first report of typhoid fever, Salmonella paratyphi A can express a CoryA Escherichia coli (CoryA) have homology of pore-forming toxins and prove that ClyA Is conserved in different serotypes of Salmonella typhimurium but is absent in Salmonella typhimurium. DNA sequence analysis revealed that the clyA-like open reading frame of Salmonella enterica serotypes S2369 / 96 and CT18 had 100% homology with the clyA coding sequence of Salmonella typhi Ty21a strain, and the nucleotide sequence of clyA_ (EC) was 87 % Homology. The clyA_ (SPa) sequence of Salmonella paratyphi S3068 / 99 has 98% and 86% homology with ClyA_ (STy) and clyA_ (EC), respectively. ClyA_ (SPa) and ClyA_ (STy) are two products of clyA gene, which have 91% and 90% identity with the amino acid sequence of A (ClyA_ (EC)) of Escherichia coli These two genes were added and cloned to form the recombinant Ty21a /