Establishment and evaluation of mice model infected Brucella abortus strain 2308 by different routes

Abstract:

[Background] Brucella can infect humans and animals by mouth, skin, mucous and respiratory tract. Mice are the most commonly used model animals in the study of Brucella. [Objective] The study aimed to establish the BALB/c mice model infected by Brucella abortus strain 2308 with different routes and doses, and to provide reference for mice infection experiments by Brucella. [Methods] The BALB/c mice were infected with 5 different doses of 10¹-10⁵ CFU by injection, mouth and eye droppings respectively. The serum samples were collected at different time points after infection in order to detect IgG, IgM and IgA antibodies. Combined with the results of spleen weight and bacteria content, we evaluated the effect of BALB/c mice model infected with Brucella by different routes. [Results] The results showed that 10 CFU was the minimum infection dose for injection, and 10⁵ CFU was the minimum infection dose for oral administration. The BALB/c mice could not be successfully infected with 5 different doses of 10¹-10⁵ CFU by eye droppings. At 10⁵ CFU infection dose, the average bacteria content per gram spleen of mice in oral and injection groups was 10^5.673 CFU/g and 10^5.009 CFU/g respectively, and there was no significant difference between them (P>0.05). However, the average weight of spleen was 0.310 g in the oral group, which was significantly higher than 0.165 g in the injection group (P<0.01). During the experimental period, the titers of IgG antibody increased continuously with the increase of infection time in injection and oral groups. Overall, the IgG peak value of oral group was significantly higher than that of injection group. The IgM change trend was coincide between the two groups. Two mice in oral group produced IgA antibody 28 days after infection, but IgA antibody was not detectable in injection group. [Conclusion] This study established the BALB/c mice model infected Brucella abortus strain 2308 by different routes.