Patent ID: 7851166

Claim:
A method of diagnosing tuberculosis by detecting a surrogate marker for active tuberculosis, the method including the steps of taking up isolated mycolic acid antigen of tuberculous mycobacterial origin or a synthetic analogue thereof in a liposome carrier to produce mycolic acid antigen-containing liposomes; immobilizing isolated mycolic acid antigen of tuberculous mycobacterial origin to produce immobilized antigens of tuberculous mycobacterial origin; obtaining a sample from a human or animal suspected of having active tuberculosis, which sample may contain surrogate marker antibodies to the immobilized antigen, dividing the sample into a first, a second and a third sample, the first sample having a lower concentration by dilution than the second and third samples; exposing part of the first sample to the immobilized mycolic acid antigen in a test vessel; exposing part of the first sample to the immobilized mycolic acid antigen in a control vessel; exposing the second sample to mycolic acid antigen-containing liposomes; exposing the third sample to liposomes not containing the mycolic acid antigen; adding the second sample, after exposure to the mycolic acid antigen-containing liposomes, to the test vessel; adding the third sample, after exposure to the liposomes not containing the mycolic acid antigen, to the control vessel; detecting binding of antibodies to the immobilized mycolic acid antigen in both the test and control vessels in real time; and comparing the degree or extent of binding between the test and the control vessels, any observed lesser binding in the test vessel being an indicator of the presence of antibodies to the mycolic acid antigen in the sample that indicates active tuberculosis in the human or animal from which the sample originated.