Abstract: The mouse model for evaluation of protective immunity was established in Brucella abortus. 6-week-old female BALB/c mice were randomly divided into 3 groups (n=40). The mice were each injected intrap eritoneally with 5.0?10⁴ CFU of strain A19 (A19-challenge-group), and another two unimmunized groups served as unimmunized-challenge-group and PBS group with 0.2 mL of PBS.At the 45-dayspost-immunization, all of mice in A19 group and challenged group were each challenged with 3.0?10⁴ CFU of the same subtype 2308 strain.Fifteen days postchallenge, mice were killed and their spleens were removed, weighed, Brucella isolation and pathological changes of organs could be detected in the mice. The results showed that the Brucella load of gram of spleen in A19-challenge-group and unimmunized-challenge-group had a significant difference than the PBS control group (P<0.05). At the 45-day-postchallenge, the result of Brucella load of gram of spleen had no significant difference between the A19-challenge-group to the PBS control group (P>0.05). However, it had significant difference in A19-challenge-group than the unimmunized-challenge-group. The mice of pathological changes in A19-challenge-group had significantly lighter than that of unimmunized-challenge-group (P<0.05). These results indicated that BALB/c mouse model could be applied to evaluate the protective immunity in Brucella abortus.

Key words: A19 strain; BALB/c mouse model; protective immunity