Project Lead(s): Devang Patel
Tuberculosis (TB) caused by Mycobacterium tuberculosis infection is the second biggest infectious-disease killer worldwide, with over 95% of TB deaths occurring in low- and middle-income countries.
Active TB infection is exclusively diagnosed by chest X-ray, sputum smear or culture tests, whereas latent TB infection (LTBI) is diagnosed by skin test or IFN-γ release test. There is no single diagnostic test for detection of both types of infection.
The project proposed to develop a novel single-diagnostic assay that would be rapid, highly sensitive and can diagnose active, latent and drug-resistant TB.
The team proposed to analyze combinations of biomarkers produced by the host during M. tuberculosis infection, such as change in expression of INF-γ, IL-15, IL-2, TNF-α by CD4+ T cells, for TB detection.
The hypothesis, based on T cells population analysis, was that they could develop a novel diagnostic assay, which would provide precise information about the type and degree of TB infection.
Experiments were conducted to standardize the assay procedure, using control human blood for the above markers and optimized FACS assay for the surface marker CD+4 T cells.
Eighty-five subjects were included in the study (15 subjects were classified as non-TB patients or healthy patients, 35 as LTBI individuals, and 35 as active TB patients).
Significant differences were also observed in levels of TNF-alpha, IFN-gamma, IL-2, IF-10 and CD+4 between TB and control patients.
However, no differences were observed between TB and LTBI patients, meaning the markers could not be used to develop a test to differentiate TB and LTBI patients.