Fig. 2.

Calibration curve of the developed sandwich ELISA for MPT64 protein (A), and detection limits of the assay (B). The calibration curve was obtained from the mean value of six sandwich ELISAs with the anti-MPT64 antibodies Mab-1A4 and Mab-2E9 under optimized conditions (A). Culture supernatants of M. tuberculosis H37Rv in Middlebrook 7H9 broth with enrichment were serially diluted and applied to the test. The cut-off of the MPT64 sandwich ELISA is indicated by a dotted line. ELISA, enzyme-linked immunosorbent assay; CFU, colony-forming unit; OD, optical density.