Construction of the O45 ler Gene Deletion Mutant of the Enteropathogenic Escherichia coli

摘要

Enteropathogenic Escherichia coli (EPEC) are important pathogens in animals and human beings. In order to obtain an attenuated vaccine candidate, a ler deletion mutant of O45 strain was constructed and the cytotoxicity together with the safety of this candidate was also evaluated. EPEC O45 ler deletion mutant was constructed and the cytotoxicity assay showed that the mutant had no cytotoxicity to Vero cells in contrast with the virulent parent strain. After inoculation of the deletion mutant, the mice with O45 (Δler) gained weight normally and experienced no clinical signs. In contrast, the mice with O45 exhibited weight loss and all dead in four days. In conclusion, O45 (Δler) deletion mutant was successfully obtained and all the data from cytotoxicity and safety assays demonstrated that O45 (Δler) deletion mutant might be an attenuated vaccine candidate.