Abstract: The present invention relates to a method of detecting an active tuberculosis infection in a serum sample from an individual. More specifically, the disclosed method uses a single chain variable fragment from a monoclonal immunoglobulin specific for mycolic acids of mycobacterial origin to detect surrogate markers, the presence of which indicate the individual has an active tuberculosis infection. Markers useful for practicing the disclosed method can be serum mycolic acid antigen, serum anti-mycolic acid antibodies or both. In a preferred embodiment, the method is practiced using a lateral flow assay format.

Abstract: 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.