Diagnosis of active tuberculosis (TB) in TB-endemic countries, where >90% of the global TB cases occur, depends upon microscopic examination of sputum smears made directly from the specimen. While this test is highly specific, the test is tedious, time-consuming, requires multiple patient visits, and has limited and variable sensitivity WHO has repeatedly expressed the need for a rapid, simple and affordable point-of-care (POC) test for TB, and has provided specifications for such a test. deTect Biosciences, LLC was founded with the goal of developing an inexpensive, rapid POC test for the diagnosis of active TB infection. The deTect rapid TB test is based on detection of antibodies against carefully selected peptides representing immunodominant sequences of cell wall proteins of M. tuberculosis (M. tb), and is the only serologic assay under development that is based on peptides rather than recombinant proteins, a feature that assures lower cost and greater specificity and reproducibility. The deTect IP portfolio contains 38 immunodominant peptides;antibodies specific for these peptides discriminate subjects with active TB from those with latent M. tb infection or BCG vaccination. During the Phase I STTR, deTect focused on a subset of nine peptides, optimized methods for conjugating these peptides to bovine serum albumin (BSA), and demonstrated that the peptide-BSA conjugates resulted in significantly enhanced reactivity (compared to unconjugated peptides) with sera from TB patients, but not from PPD+ subjects. Evaluation of these peptide-BSA conjugates initially by ELISA and subsequently on a lateral flow format showed that the use of optimal peptide-BSA combinations can provide high sensitivity and specificity and forms the basis of a sensitive and specific lateral flow POC diagnostic test for active TB. The goals of the Phase II studies are to select an optimal subset of peptide-BSA conjugates with which to prepare a prototype of the deTect TB rapid lateral flow diagnostic kit, and to validate its performance, concurrent with developing all documentation needed for commercialization. Specifically, we propose to select the optimal subset of peptide-BSA conjugates for detection of active TB (Aim # 1), devise a rapid lateral flow TB diagnostic test based on the peptide-BSA conjugates selected (Aim # 2), and validate the performance of the deTect assay using prototype kits by testing specimens from appropriate cohorts as described in the applications. The criteria for the success of the test will be driven by the WHO standards proposed for a TB diagnostic serological test. By the end of Phase II, we anticipate that the non-clinical specifications (stability, robustness, prototype design, production, etc.) an clinical requirements (sensitivity and specificity) of the deTect POC TB rapid test will be documented and that the product will be ready for limited production and field testing.
The work proposed will ultimately lead to development of an inexpensive, robust, and rapid ELISA diagnostic and a point-of-care device for detection of active TB infections. No reliable rapid assay for active TB currently exists. The deTect Biosciences assay would help deliver effective treatment for patients and potentially reduce the spread of TB and mortality.
