¹The Key Bio-Engineering and Technology Laboratory of National Nationality Commission, College of Life Science and Engineering, Northwest University For Nationalities, Lanzhou 730030, CHINA DOI : 10.9775/kvfd.2017.18644 Brucella poses a great threat to animal and human health, and vaccination is a good way of controlling the bacterium. In this study, the immune response and protection ability of a recombinant adenovirus Ad-LL/BP containing L7/L12 and BCSP31 proteins of Brucella abortus (B. abortus) were evaluated in BALB/c mice model. Firstly, Adenovirus vector Ad-CMV and the recombinant adenovirus Ad-LL/BP were amplified in HEK 293AD cells. The TCID50 values of Ad-LL/BP and Ad-CMV were 10−8.68/0.1 mL and 10−8.35/0.1 mL, respectively. Mice were inoculated with 100 TCID50/mouse of Ad-LL/BP or Ad-CMV. Vaccination of mice with Ad-LL/BP vaccine was able to elicit higher IgG, IgG1 and IgG2a antibody levels when compared with Ad-CMV and PBS control animals (P<0.05). Splenocytes from Ad-LL/BP-immunized mice significantly proliferated and released Th1 type cytokine IL-12 in comparison with Ad-CMV or PBS-inoculated groups (P<0.05). CD3+ and CD4+ T cell subset in splenocytes from the mice immunized with Ad-LL/BP vaccine were significantly higher compared with those from the mice vaccinated with Ad-CMV or PBS (P<0.05), but CD8+ T cells had no change in the three groups (P>0.05). Ad-LL/BP vaccine was able to reduce significantly the numbers of B. abortus in the spleens from the immunized mice. These results indicated that the recombinant Ad-LL/BP vaccine induced mainly cell-mediated immunity and partly humoral immunity, and provided moderately protection against B. abortus infection. Therefore, the vaccine could be further developed into a live-vector vaccine against B. abortus. Keywords : Brucella abortus, L7/L12, BCSP31, Adenovirus, Immunity, BALB/c mice