抑制差减杂交筛选禽致病性大肠杆菌基因组差异片段及其分析

采用抑制差减杂交技术(Suppression subtractive hybridization,SSH)对禽致病性大肠杆菌E037株(血清型O78)与非致病菌株K-12MG1655以及同一O2血清型高致病菌株E058与低致病菌株E526进行基因组差异片段克隆与分析。从E037株中共检出17个特异性差异片段,E058株中共检出32个特异性差异片段。经同源分析,这些序列可分为4类:质粒相关序列、噬菌体相关序列、已知功能序列、未知功能序列。这些差异片段包含许多重要的大肠杆菌毒力相关基因,如大肠杆菌素、气杆菌素受体、铁基因簇等。49个片段中,14个片段与其它微生物基因组同源性较高。结果表明,大肠杆菌高致病株与低致病菌株或非致病菌株基因组间存在较多差异基因,其中包括毒力、毒力相关基因、代谢以及噬菌体等基因成分。

Identification of genomic differences in avian pathogenic Escherichia coli using suppression subtractive hybridization analysis

To identify unique DNA fragments associated with avian pathogenic Escherichia coli strains, suppression subtractive hybridization (SSH) was used. The genome of nonpathogenic E. coli K-12 strain MG1655 was subtracted from the genome of avian highly pathogenic strain E037 (serotype O78) resulting in the identification of 17 specific fragments. And the genome of avian low pathogenic E. coli strain E526 (serotype O2) was subtracted from the genome of avian highly pathogenic strain E058 (serotype O2) resulting in the identification of 32 specific fragments. Sequence homology analysis was done and four types of fragments were identified: plasmid sequences, phage sequences, sequences with known function and sequences without any currently known function. And 12 specific fragments that were not found in E. coli K-12 were identified from two avian E. coli strains. The results suggested that there were some genetic differences between the highly pathogenic strains and low pathogenic or nonpathogenic strains.