Abstract
This study aimed to compare the suitability of three chimeric recombinant outer membrane proteins of Brucella (rOmps 19 + 25, 19 + 31, and 25 + 31) for the diagnosis of bovine and sheep brucellosis using an indirect ELISA (i-ELISA). The diagnostic properties of these proteins in an i-ELISA were studied using blood serum samples from cattle and sheep with known positive and negative results for brucellosis based on the rose Bengal plate test (RBT), complement fixation test (CFT), and a commercial ELISA (c-ELISA) kit, as well as using animal sera from fresh foci of infection with unknown reactivity. rOmps19 + 31 and 19 + 25 conferred 99–100% specificity to the i-ELISA compared with RBT, CFT, and c-ELISA in both bovine and sheep sera testing. i-ELISA/rOmp19 + 31 exhibited a higher sensitivity in serological examinations of cattle than in that of sheep, compared to RBT (89% vs. 44%) and CFT or c-ELISA (78% vs. 42%). In the study of cattle and sheep residing in the fresh foci of infection with positive RBT, anti-Brucella antibodies were detected by i-ELISA/rOmp19 + 31 in the blood serum of 80% and 86% of animals with the test specificities of 100% and 70%, respectively. These results indicate rOmp19 + 31 as a potential target antigen for the diagnosis of bovine and sheep brucellosis; however, further large-scale studies are required to determine the effectiveness of this protein as an i-ELISA antigen.