In Vitro and In Vivo IFN-γ and IL-10 Measurement in Experimental Brucella abortus Biotype 1 Infection in...

The immune response to Brucella abortus mainly depends on antigen-specific T cell activation, CD4⁺ and CD8⁺ T cells, and Brucella-specific humoral response. Protective immune response against Brucella infection has not been performed in the Sprague-Dawley (SD) rat model. We measured bacterial kinetics in addition to in vivo and in vitro interferon gamma (IFN-γ) and interleukin-10 (IL-10) production against crude Brucella protein in the SD rats at different days of postinfection with B. abortus biotype 1 by indirect enzyme-linked immunosorbent assay. Forty SD rats were inoculated intraperitoneally with 0.1 mL sterile injectable pyrogen-free solution containing 1 × 10¹⁰ colony-forming units/mL of B. abortus biotype 1 obtained from cattle in Korea. Four rats were used as uninfected control. Serum IFN-γ level at 3 and 7 days postinfection were significantly higher (p > 0.001) compared with the IL-10 level. On the contrary, serum IL-10 levels were observed significantly higher at 21 and 28 days postinfection compared with the serum IFN-γ levels (p < 0.001). The production of IFN-γ by spleen cells was significantly higher at 7 and 14 days postinfection compared with IL-10 (p < 0.001). On the contrary, IL-10 productions were found to be significantly higher at 21, 28, 35, and 42 days postinfection compared with IFN-γ (p < 0.001). The presence of B. abortus in blood was marked till 5 weeks of infection, throughout the experiment in case of spleen, and no bacteria were isolated from the kidney and liver at 6 weeks postinfection. The in vivo and in vitro IFN-γ and IL-10 measurement in our study reported that B. abortus infection in rats primarily educe T helper (Th)1-dominant immune response in acute infection accompanied by Th2-dominant immune response in chronic infection.