The goals of this proposal are to devise rapid serological tests that can replace the sputum smear test for the diagnosis of active TB and meets the WHO specifications to replace microscopy in resource-limited countries based on immunodominant peptides from three M. tb cell-wall proteins. Although direct smear microscopy is highly specific, the test is tedious, time-consuming, requires multiple patient visits before diagnosis, and has limited sensitivity. The Company's approach is based on the prior identification of three cell wall proteins of M. tuberculosis (PTRP, PE-PGRS51 and LipC) that are highly immunogenic in TB subjects, but not in individuals with latent TB infection (LTBI). The identified immunodominant epitopes were mapped and combinations of immunodominant peptides derived from these proteins are predicted to detect >95% of smear positive TB patients. Specifically we plan to devise microplate ELISA assay(s) based on the peptide combinations demonstrating maximum sensitivity and specificity for detection of anti- TB antibodies in sera, and to verify the performance of the assays with a panel of sera from cohorts of TB-negative subjects (Aim #1);to translate the microplate ELISA assay to a lateral flow point-of- care format using the 9 immunodominant individual peptides previously identified (Aim #2);and to identify the best peptide combination(s) to use in a multiplexed lateral flow device to result in maximum sensitivity and specificity. This assay will be validated with large-panels of clinical samples (Aim #3). During Phase 2, we plan to further validate and refine the rapid test with samples from diverse geographic sites and advance commercialization of both the microplate and rapid lateral flow assays. Testing will be performed with both serum and oral fluids samples. This will allow the Company to determine if it is necessary to have region-specific tests or if one combinatorial test is appropriate worldwide. The development of a non-invasive salivary and/or serum diagnostic test for active TB will fill an urgent need in resource-limited areas.
The work proposed will ultimately lead to development of an inexpensive, robust, and rapid diagnostic ELISA test and point-of-care device for active TB infections. No reliable rapid test for TB currently exists and this assay would represent a major advance.