LAUSR

Brucellosis is endemic in Asia, Sub-Saharan Africa, some countries of Latin America, the Middle East and the Mediterranean and South Eastern Europeean Region (30). The disease causes not only great economic losses in animal husbandry, but also poses a serious threat to public health (2, 15). A complicated epizootic and epidemiological situation for brucellosis persists in the Republic of Kazakhstan where the disease remains endemic (21, 33). The efficacy of brucellosis control and eradication programs primarily depends on the timely detection of infected animals by serological tests. The conventional serological tests for diagnosing bovine brucellosis in Kazakhstan are the agglutination test (AT), complement fixation test (CFT) and rose bengal test (RBT). These tests which are based on the use of Brucella cells smooth lipopolysaccharides (S-LPS) as an antigen do not always give reliable results because of cross-reactivity with other Gram-negative bacteria (3, 14, 37). Therefore, there has been an ongoing search for non-LPS candidates, namely protein antigens, for the diagnosis of brucellosis (12, 13, 22). Outer membrane proteins (Omps) of Brucella spp. were originally identified on the basis of their molecular weight (mol.wt.) (29). Group 1 was identified as minor (94 or 88 kDa). Major Brucella Omps have been classified in group 2 (36 to 38 kDa) and group 3 (Omp25 and Omp31) (11). Moreover, Omp28 was identified as another member of group 3 (26). The latter has been approved as useful for the differentiation of infected sheep from vaccinated ones (16). Several recombinant Omps (rOmps), including those with lower mol.wt., were obtained and tested in ELISA a for serological diagnosis of animal brucellosis like rOmp10, rOmp19 and rOmp28 (34), rOmp16 (20), rOmp25 (10), rOmp28 (9, 25, 27) and rOmp31 (18). The main obstacle for introducing these recombinant proteins into diagnostic practice is their lack of sensiUsing combined recombinant protein in the diagnosis of bovine brucellosis