A METHOD OF DETECTING SURROGATE MARKERS FOR ACTIVE TUBERCULOSIS IN A SERUM SAMPLE

摘要

The invention provides a method of detecting surrogate markers for active tuberculosis in a serum sample. The surrogate markers are selected from serum mycolic acid antigen, serum anti-mycolic acid antibodies or both. The method includes the steps of combining the serum sample with a labelled monoclonal immunoglobulin antibody or fragment thereof to mycolic acids to produce a combined serum sample, the antibody or fragment thereof not substantially cross-reacting with cholesterol and the label being selected so that binding of the labelled antibody to immobilized mycolic acid antigen of mycobacterial origin produces a detectable signal and combining a blank sample with the labelled monoclonal immunoglobulin antibody or fragment thereof to mycolic acid to produce a combined blank sample. The method includes exposing both samples to immobilised mycolic acid antigen of mycobacterial origin or a synthetic analogue or analogues thereof so that the labelled immunoglobulin antibodies or fragments thereof in each sample bind to the immobilised antigen to produce detectable signals. If the surrogate markers are present, the signal produced by the blank sample will be stronger than that produced by the serum sample because of inhibition of binding of the labelled antibody in the serum sample arising from prior binding of the labelled antibody with the mycolic acid antigen in the serum sample or by competitive binding of serum anti-mycolic acid antibodies in the serum sample to the immobilised mycolic acid antigen or both.