Development of a Multiplex Bead Assay to Detect Serological Responses to Species in Domestic Pigs and Wild Boar with the Potential to Overcome Cross-Reactivity with O:9.

The aim of this study was to develop a multiplex bead assay using a rLPS antigen, a smooth antigen, and a O:9 antigen that not only discriminates -infected from -uninfected pigs and wild boar, but also overcomes the cross reactivity with O:9. Sera from 126 domestic pigs were tested: 29 pigs were infected, 80 were non-infected and 17 were confirmed to be false positive serological reactors (FPSR). Sera from 49 wild boar were tested: 18 were positive and 31 were negative. Using the rLPS antigen, 26/29 -infected domestic pigs and 15/18 seropositive wild boar were positive, while 75/80 non- infected domestic pigs, all FPSR, and all seronegative wild boar were negative. Using the smooth 1330 antigen, all -infected domestic pigs, 9/17 FPSR and all seropositive wild boar were positive, while all non-infected pigs and 30/31 seronegative wild boar were negative. The ratio of the readouts from the smooth antigen and O:9 antigen enabled discriminating all infected individuals from the FPSR domestic pigs. These results demonstrate the potential of this assay for use in the surveillance of brucellosis, overcoming the cross-reactivity with .