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致病性和出血性大肠杆菌 (代表株 EPEC E2 34 8和 EHEC O15 7)是婴幼儿腹泻、出血性结肠炎和尿路感染综合征 (尿毒症 )的主要病原菌 ,它们同属于粘附脱落 (Attaching/ Effacing,A/ E)大肠杆菌群 ,具有许多共同的毒力基因 ,定位于致病岛 L EE(the locus of enterocyte effacement)上。本试验主要就 A/ E大肠杆菌致病岛 L EE的 2个主要调节基因 lux和 ler基因对细菌致病性和免疫原性的影响进行了研究。所使用的始发菌株为兔致病性大肠杆菌 RDEC- 1,根据同源重组的原理 ,利用自杀性载体 p CVD44 2技术 ,敲除了位于染色体上的 lux和 ler基因 ,构建了 lux和 ler基因缺失突变株 ,研究了这 2个基因对细菌生长、毒力因子表达的调控作用以及基因缺失突变株的致病性和免疫保护作用。家兔实验研究表明 ,lux基因缺失突变株仍然残存着部分致病作用 ,不足以成为理想的致弱疫苗 ;而 ler基因缺失突变株安全性好 ,具有良好的免疫保护作用 ,是理想的家兔致弱疫苗候选株。这些研究资料为人 A/ E大肠杆菌疫苗 ,尤其是 EHEC O15 7疫苗的研制指明了方向 ,并提供了技术路线。
Pathogenic and hemorrhagic Escherichia coli (representative strains EPEC E2348 and EHEC O157) are major pathogens of infantile diarrhea, hemorrhagic colitis and urinary tract infection syndrome (uremia), both of which belong to the group of adhesion and shedding Attaching / Effacing, A / E) Escherichia coli, with many common virulence genes, locates on the locus of enterocyte effacement. In this study, the effects of lux and ler, the two major regulatory genes of A / E Escherichia coli pathogenicity island EE, on the pathogenicity and immunogenicity of bacteria were studied. The original strain was rabbit pathogenic E.coli RDEC-1. Based on the principle of homologous recombination, lux and ler genes were deleted by chromosomal lux and ler genes by suicide vector p CVD44 2 Deletion of mutant strains, the study of the two genes on bacterial growth, the regulatory role of virulence factors and gene deletion mutant pathogenicity and immune protection. Rabbit experimental studies have shown that, lux gene deletion mutant still remains part of the pathogenic role, not enough to become an ideal attenuated vaccine; and ler gene deletion mutant is safe and has good immune protection, is the ideal rabbit Weak vaccine candidates. These studies point the way for the development of the human A / E E.coli vaccine, especially the EHEC O157 vaccine, and provide a technical roadmap.