Mycobacterium tuberculosis (Mtb), an NIAID Category C agent, infects approximately one-third of the world's population, and an estimated 9.4 million people develop active tuberculosis (TB) each year. The poor detection rate of TB cases, especially in developing countries, promotes this level of ongoing transmission. In resource-poor regions, direct microscopic examination of sputum smears for acid fast bacilli (AFB) provides the prime diagnostic tool. The AFB smear test exhibits poor sensitivity at approximately ~50% in immunocompetent persons, and is even less sensitive in HIV+ TB+ patients. In order to interrupt this cycle of infection-transmission, we need improvements in rapid diagnostic capabilities, independent of Mtb-specific nucleic acid detection, for difficult to diagnose patients like those co-infected HIV. Towards that end, these proposed studies will demonstrate that detection of antibody biomarkers produced in response to active TB would add a powerful adjunct to the current diagnostic armamentarium. To accomplish this, we will obtain sera from well-defined patient and control groups, and screen these sera on a unique and novel platform, nucleic acid programmable protein arrays (NAPPA), which allows for display of the complete proteome of Mtb on a microarray. The screen of a complete representative proteome using patient and control sera will allow us to delineate a smaller set of target proteins which we will validate using an acquired set of independent samples obtained in cross-sectional studies of TB suspects. The results of the validation study will yield a select set of ~30 candidate proteins that could serve to detect antibody biomarkers in TB patients. We will then test these in Enzyme-Linked-Immunosorbent Assays (ELISA) to validate the data acquired in the microarray studies and to provide prototyping of a diagnostic. The antigen-antibody interaction provides the foundation for many diagnostics, which will allow transferring these discoveries into a commonly used point-of-care technology platform, such as the "dipstick" style test, or into emerging electronic biosensor platforms. Our goal is to find and delineate the most sensitive and specific Mtb proteins that react with patient antibodies. Our assembled team couples the expertise of both TB patient care and diagnosis with high throughput genomics, proteomics, and antibody screening to accelerate progress on this ancient disease. The successful completion of this program will provide new and improved strategies for detecting TB rapidly and sensitively, in formats that can be applied in all settings globally.
Better tools are needed to detect and treat active tuberculosis, a global public health problem due to infection with Mycobacterium tuberculosis. This is especially important for resource-poor geographic areas with high incidence of HIV co-infection where both diseases are fueling each other. We will combine well-defined patient groups with a unique high technology protein microarray tool to test thousands of pathogen proteins for the ones that elicit antibody biomarkers that will form the foundation for a simple diagnostic device (that resembles a pregnancy test) for global use, including resource-poor environments.
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