Differentiation of Brucella vaccinated and infected mice using Poly-B antigen in sandwich ELISA

Monitoring or serosurveillance of brucellosis requires a serological test which can differentiate between vaccinated and infected animals. In the present study, an attempt was made to develop sandwich ELISA using polysaccharide-B antigen released from rough strain of B. melitensis B115. Forty four BALB/c mice were vaccinated with B. melitensis Rev 1 (1×10⁵ CFU) and another forty four were infected with B. melitensis S16M (5×10⁴ CFU). Sera samples were collected at 4, 6 and 8 weeks post vaccination/infection. There was clear difference in optical density values in sera of vaccinated and infected mice at all the serum dilutions. More elaborate study on large number of samples is required before arriving at a definite conclusion.