Y. enterocolitica O:9 bioconjugate as a promising antigen for the diagnosis of bovine brucellosis. A) Magnetic bead-based immunoassay for detection of antibodies against Brucella abortus O-antigen. Magnetic beads coated with the AcrA-OAg glycoconjugate were incubated with the indicated bovine serum samples (dilution 1/200). Bound antibodies were detected using a Cy5-conjugated goat anti-bovine IgG. The bar graph data represents the means and standard deviation for two separate determinations. Control: magnetic beads incubated with PBS-Tween 0.1%. B) Immunoblot of the same bovine serum samples.