Abstract
This study was aimed to determine the possible effect of brucellosis on the oxidative/anti-oxidative status and some immunological parameters. A total of 1432 sera from infected as well as brucellosis negative private bovine farms located in Giza governorate were collected. These serum samples were tested serologically for bovine brucellosis using Rose Bengal Plate test (RBPT), serum agglutination test (SAT), rivanol test (Riv.T) and complement fixation test (CFT). Based on serological results, four groups were created as follows; 24 selected positive serum samples of infected cows (Group A), 18 selected positive serum samples of infected buffaloes (Group B), 20 and 13 selected negative serum samples of Brucella negative cow and buffalo herds into (Group C) and (Group D) respectively. To support serological findings, bacteriological examination was done and resulted in the recovery of 3 isolates recognized as Brucella melitensis biovar 3. Evaluation of oxidative stress using malondialdehyde and the activity of anti-oxidant enzymes (catalase and superoxide dismutase) was investigated in these groups and revealed insignificant differences between cattle and buffaloes and a significant elevation of these parameters in infected bovine groups. Serum interferon gamma (IFN-γ) levels displayed a significant decrease in Brucella infected groups. The levels of serum interleukins 10 (IL-10) were significantly increased in the infected groups. Under the field of this investigation, authors concluded that the significant elevation of several stress biomarkers in the infected groups may contribute to the resistance of the Brucella to oxidative damage during intracellular proliferation. Besides, the significant decrease of IFN-γ accompanied by a significant increase in IL-10 in a response to stimulation by Brucella antigens is reflecting the capability of Brucella to survive intracellularly under the harsh condition for a long term. Accordingly, further studies of immune mechanisms against Brucella may help in the development of novel therapeutic or new vaccine approaches

Key words: Oxidative stress, anti-oxidant enzymes, IFN-γ, IL-10, Brucellosis