关键词: 大肠杆菌； 奶牛乳房炎； 动物模型； 人病兽防

Abstract: In order to better evaluate the effectiveness of preventative vaccines and therapeutic drugs，we aimed to establish a stable dairy cow mastitis model，which may provide a reliable way to verify the concept of“human disease and animal prevention”for extensively infectious diseases. Milk samples from dairy cows with clinical mastitis were collected from different regions of China. Different strains of E.coli were used to infect 6-8 weeks old Balb/c mice and 2- 6 years old healthy susceptible cows in late stage of lactation respectively after bacterial isolation and identification. The infectivity and pathogenicity of the different strains against mice and dairy cows were determined， and strong virulent strains with high pathogenicity for both species were chosen for in vivo infection. The susceptible cows were inoculated with the selected candidate virulent strains，and the differences of clinical manifestations，daily milk yields，milk bacterial counts and somatic cell counts were recorded. Meanwhile，the mice were infected by the same strains，and the clinical symptoms and death of mice were recorded to establish a stable animal model of E.coli infection. Results：Three virulent E.coli strains（LZ06，ESH05，EHL11） of different serotypes were obtained，which could induce typical clinical mastitis in dairy cows and death in mice. The mastitis models in dairy cows and a lethal model in mice were finally established using virulent strain LZ06. Conclusion：The virulent strains of E.coli causing mastitis were successfully screened，and the animal mastitis model was successfully established，which could be used to evaluate the protective effects of vaccines or medicine. This study provided the new method and strategy for evaluating the concept of“human disease and animal prevention”for zoonosis.

Key words: Escherichia coli； Bovine mastitis； Animal model； Human disease and animal prevention