猪水肿病大肠杆菌贵州分离株毒素Stx2e对Vero细胞的毒性作用

Cytotoxicity of Stx2e from Escherichia coli isolated from pigs with edema disease in Guizhou province

猪水肿病毒素即Ⅱ型志贺毒素变异体e亚型(Shiga toxin 2e,Stx2e)。采用吖啶橙/溴化乙锭(AO/EB)双荧光染色法和四甲基偶氮唑盐(MTT)比色法,比较了从患水肿病猪粪便样品中分离的28株大肠杆菌所产志贺毒素对Vero细胞的毒性作用。结果显示,MTT比色法检测的细胞比活力与AO/EB染色法检测的正常细胞与早期凋亡细胞比率之和呈正相关。将28株菌株产生的Stx2e作用于Vero细胞,均能抑制Vero细胞的生长,并诱导Vero细胞的凋亡;其中8株病原菌所产Stx2e毒素对Vero细胞的毒性作用强于O157∶H7。这些毒素的毒力差异可能与其A亚基基因的结构变异有关。结果提示,贵州分离的产Stx2e大肠杆菌的毒力存在一定差异,其中部分菌株的毒力作用较强,应加强对养殖场仔猪的保护。

To compare the toxicity of Shiga toxin 2e（Stx2e） of 28 strains of shiga toxin-producing Escherichia coli（STEC） isolated from feces samples of piglets with edema disease,Vero cells were used to detect the growth and apoptosis using acridine orange/ethidium bromide（AO/EB） fluorescence staining and 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide（MTT） assay.The results showed that there was a positive correlation between Vero cell activity determined by MTT and the sums of cells at early-stage of apoptosis and normal cells tested by AO/EB fluorescence staining.It was confirmed that all the prepared Stx2e toxins from 28 strains inhibited the growth of Vero cells and induced obvious apoptosis.Furthermore,the toxicity effects of Stx2e from 8 STEC strains were much stronger than that of O157∶H7.The toxicity difference might be due to the variety of the genes coded for Stx2e subunit A.It suggested that there are some differences in the virulence of some strains of STEC in Guizhou province and the protection of farm piglets should be strengthened.