Essential TB Protein Detected in Clinical Sputum Samples

TB is difficult to diagnose and current diagnosis generally relies on an insensitive 100-year-old technique of smear microscopy. The TB diagnostic market lacks a simple, rapid, and cost effective test to accurately identify TB. The rapid assays developed to date rely on the detection of a human response to TB infection. The disease causes high mortality in developing countries and is a leading cause of death among people infected with human immunodeficiency virus (HIV).

Approximately one third of the world's population, or 2 billion people, have been exposed to the TB pathogen causing about 9 million infections and 2 million deaths annually. While TB is predominantly a disease of developing countries (718 cases per 100,000 people in South Africa), the incidence in developed countries has risen significantly (13 per 100,000 in the United States), due to the global spread of HIV and increased immigration and travel. Coinfection with HIV is a particular problem for accurate diagnosis of TB and for compromising the effectiveness of the antiretroviral drugs used to treat HIV.

Tyrian Diagnostics (Sydney, Australia) identified proteins from the bacteria that cause TB--Mycobacterium tuberculosis--circulating in blood and/or sputum in people diagnosed with the disease. The company has competed Milestone 4 of a feasibility study in collaboration with Becton, Dickinson and Company (BD; Franklin Lakes, New Jersey, USA) to determine the suitability of Tyrian's TB protein markers for the development of rapid diagnostic tests to detect active TB disease.

The study demonstrated detection of selected TB proteins in sputum. Methods for sample preparation and testing suitable for use in the field were developed. Tyrian identified a lead marker that appears to be particularly suitable for a diagnostic test because it is an essential TB protein, meaning that it is always present when there is active TB. In an adjunct study, Tyrian demonstrated that this same marker could also be developed as a molecular diagnostic assay.

"This collaborative study with BD has identified two potential products for development using our lead marker," said Jenny Harry, CEO of Tyrian Diagnostics. "A molecular diagnostic test could be developed, using existing gene expression technology, for primary use in hospitals, clinics, and analytical, and research laboratories. Secondly, an antigen-based Point-of-Care test would address a broader market by providing an immediate result without the need for laboratory facilities."

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