Advancing diagnostics for tuberculosis

TB, affecting one third of the human population, is caused by Mycobacterium tuberculosis (MTb). TB is a leading killer of people infected with HIV, and the appearance of multi-drug-resistant strains of MTb further complicates the problem. Currently, no efficient and cost-effective tests are available for early diagnosis of TB, and there are no tests that can differentiate millions of infected people from active TB patients.

Closely related bacteria M. bovis causes bovine TB, found worldwide. The principal hosts for bovine TB are cattle and buffalo, however many other domestic and wild animals can become infected.

The DEMO-NOPERSIST (Demonstration of NOPERSIST results leading to novel, validated diagnostic tests for active human and bovine tuberculosis) project aims to produce marketable diagnostic products for TB in people and cattle, and also to differentiate between latent and active infections in people. This two-year project, to be completed in September 2015, puts the results of the previous EU project NOPERSIST into practice.

Stages of disease can be assessed through interferon gamma (IFN-gamma) and interleukin 2 (IL-2), secreted by the T helper cells of the immune system. To develop diagnostics, the partners already selected and are producing recombinant antigens from MTb. They are developing the monoclonal antibodies, anti-IL-2 and anti-IFN-gamma, which will be used for kit production.

Human IFN-gamma and IL-2 tests are developed in several formats. The ELISA test contains 96-well microtiter plate, coated by IL-2- and/or IFN-gamma-specific antibodies, ready-to-use detection antibody, conjugate and the necessary buffers. The cytokine release assay (human ELISPOT test) contains ready-to-use stimulating antigens, coating and detection antibodies, streptavidin-horseradish peroxidase conjugate and substrate solution. A bovine TB diagnostic is being developed in a lateral flow format.

The ability to differentiate between latent and active TB is of extreme importance, considering a large percentage of the infected population remains otherwise healthy. The developed diagnostics will have an immense positive impact on human health and prevention of TB.