A single-domain antibody-based lateral flow assay for Tuberculosis

About This Grant

PROJECT SUMMARY Despite significant efforts over the past century, tuberculosis (TB) remains a formidable global health challenge. Mycobacterium tuberculosis (Mtb), the causative agent of TB, infects approximately 2 billion people worldwide. According to the WHO, the incidence of TB began rising for the first time in decades in 2021, in 2022 there were an estimated 10.6 million new cases, and 1.3 million lives lost. Despite these alarming numbers, a significant gap in the fight against TB remains due to the lack of effective diagnostic measures. As many as 30% of estimated cases go undiagnosed, a severe oversight that fuels community transmission and hinders disease control efforts. The situation is further exacerbated by the emergence of multidrug resistant strains, making prompt and accurate diagnosis increasingly vital. To address this unmet medical need, we propose the development of a low-cost, low-complexity TB lateral flow assay (LFA)-based diagnostic test, offering convenience comparable to the COVID-19 at-home rapid antigen tests. Our innovative approach centers on the use of variable heavy chain antibody fragments (VHH), also known as single-domain antibodies. These antibody fragments are just one-tenth the size of conventional antibodies and possess several advantageous features including high thermostability and low production costs. They can also achieve higher binding site density due to the removal of FC domains, improving their potential sensitivity. These characteristics make VHHs particularly well-suited for low-cost point-of-care diagnostics. We intend to focus on the detection of Mtb derived antigens shown to have strong performances in more complex and more expensive diagnostic approaches. In this Phase I application, we propose to refine a VHH optimization platform, leveraging our established phage-display discovery process and our existing VHH candidates, and we will also produce and test bivalent VHH constructs using a rapid screening method. We will then produce two LFA prototypes (visual read and fluorescent), and test them using real-world TB samples to determine the sensitivity and specificity of our test. Upon completion of this study, we expect to have prototype LFAs utilizing well-characterized VHH candidates capable of effectively detecting TB antigens in clinical TB samples. This foundational work will forward development of a test for rapid and efficient TB case finding in low-resource settings, addressing a major gap in accessible, cost-effective TB diagnostics. We hope to bring this vital technology to regions bearing a high burden of the disease, thereby contributing significantly to the global effort to eradicate TB.