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在肠毒素大肠杆菌（ＥＴＥＣ）ＬＴｈ－ＳＴＩａ－ＳＴＩｂ三价基因探针的基础上，用限制性内切酶ＥｃｏＲｌ酶切，回收片段．重新构建ＬＴｈ－ＳＴＩｂ二价基因探针的克隆株。用辣根过氧化物酶复合物（ＨＲＰ）直接标记二价基因探针，建立了增强型化学发光反应（ＥＣＬ）检测ＥＴＥＣ的方法．其敏感性可测到０．１ｐｇ的质粒ＤＮＡ或由１０个菌体培养而来的ＥＴＥＣ细胞，与同位素标记杂交方法的敏感性一致．且此探针仅与产ＳＴＩｂ、ＬＴｈ肠毒素的人源性ＥＴＥＣ菌株杂交，与ＳＴＩａ肠毒素菌株及其它非ＥＴＥＣ菌株均无杂交信号．该探针与三价探针及ＬＴｈ单价探针联合使用，能间接将ＬＴｈ、ＳＴＩａ和ＳＴＩｂ３种肠毒素分型。结果表明该方法简便快速、特异敏感，无放射性污染，是ＥＴＥＣ实验室诊断及分子流行病学调查的有效工具。
Based on the LTh-STIa-STIb trivalent gene probe of enterotoxigenic Escherichia coli (ETEC), the fragment was digested with the restriction enzyme EcoRl and recovered. Cloned strain reconstituted with LTh-STIb bivalent gene probe. The method of enhanced chemiluminescence (ECL) detection of ETEC was established by direct labeling of bivalent gene probe with horseradish peroxidase complex (HRP). Its sensitivity can detect 0.1pg of plasmid DNA or ETEC cells cultured from 10 bacterial cells, and isotope labeled hybridization method sensitivity. This probe hybridized only with human ETEC strains producing STIb and LTh enterotoxins and had no hybridization signal with STIA enterotoxin strains and other non-ETEC strains. This probe, in combination with trivalent probes and LTh monovalent probes, indirectly genotypes LTt, STIa and STIb3 enterotoxins. The results show that the method is simple, rapid, sensitive and radioactive. It is an effective tool for ETEC laboratory diagnosis and molecular epidemiology investigation.