To understand the genetic variation of cytolysin activator(CylA) gene in Enterococcus faecalis , 2 pairs of specific primers were designed and synthesized according to the CylA gene sequence from GenBank for the 4 clinical isolates causing goose septicemia. The CylA gene was cloned into pMD18-T vector, and the recomfainant plasmid was screened to sequence and compared with the CylA genes of 4 pathogenic Enterococcus faecalis from patients in foreign countries and pigs in China respectively. The homology was alignmented and phylogenetic tree was reconstructed with Lasergene 7. 0. Result showed that CylA genes of 4 strains from goose were average 1 239bp in average, where was a completed open reading frame encoding 412 amino acids. No deletion and insertion in sequences, while only one nonsense mutation did not cause the variation of amino acid. There was not much variation in the remaining 8 strains of CylA gene and the deduced amino acids. The amino acids deduced by these CylA genes of 4 strains from goose shared 100 % homology. They were also close to the amino acids deduced by CylA genes of bacteria from patients in foreign countries and pigs in China, sharing the homologies of 98. 6% to 100%. These results indicate that CylA gene in Enterococcus faecalis is highly conserved, which is likely to become the target genes of detection and diagnosis as well as immunoprophylaxis.%目的 了解粪肠球菌溶血素激活因子(CylA)基因的遗传变异情况.方法 根据GenBank上已发表的粪肠球菌CylA基因序列设计2对特异性引物,对临床分离的4株致鹅败血症粪肠球菌CylA基因进行克隆及序列测定,并与国外从人体分离的和国内从猪体分离的各4株致病性粪肠球菌的CylA基因,用LaSergene 7.0软件进行同源性比对和构建系统进化发育树.结果 鹅源4株茵CylA基因均长1 239bp,有1个完整的开放阅读框,编码412个氨基酸；序列中无缺失和插入,仅有l处未引起其编码氨基酸变异的无义突变.其余8株菌CylA基因及推导的氨基酸变异程度均不大.4株鹅源菌CylA基因推导的氨基酸同源性为100％；与国外人源菌和国内猪源菌CylA基因推导的氨基酸遗传距离也较近,同源性为98.6％～100％.结论 粪肠球菌CylA基因高度保守,有可能成为检测诊断和免疫预防的靶基因.
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