Direct detection of Yersinia pestis from the infected animal specimens by a fiber optic biosensor

The FOB-3, a new type fiber optic biosensor, is designed to rapidly detect a variety of biological agents or analytes with better stability, sensitivity and specificity. In order to detect Y. pestis, a sandwich immunoassay was developed by using the purified antibody against antigen FI immobilized on polystyrene probes as the capture antibody and the monoclonal antibody-Cy5 conjugate as the detector. After a series of optimization for the stability, sensitivity and specificity of the FOB-3, 50–1000 ng/ml of antigen FI and 6 × 101–6 × 107 CFU/ml Y. pestis could be detected constantly in about 20 min, and Y. pestis could be detected specifically from Y. pseudotuberculosis, Y. enterocolitica, B. anthracis and E. coli. Then, 39 blind samples, including 27 tissues of mice infected with Y. pestis and 12 tissues of healthy mice as negative control, were detected with the FOB-3. 92.6% infected tissues were identified from the tissues of healthy mice and the tissues containing more than 100 CFU/ml bacteria could be detected by the biosensor. The results demonstrated the feasibility of the FOB-3 as an effective method to detect Y. pestis rapidly and directly from the infected animal specimens with the advantage of portability, simple-operation as well as high sensitivity and specificity.