A Novel Electrochemical LFA for Diagnosing TB from a Single Drop of Blood

Tuberculosis (TB) causes over 1.3 million deaths per year and active TB (ATB) disease in over 10 million new individuals annually. However, in 2022, over 40% of reported TB patients were diagnosed based only on clinical judgment, while an additional ~3 million individuals with ATB were neither detected nor reported. This lack of diagnostic rigor results in an inefficient health system that perpetuates TB transmission, fuels drug resistance, and jeopardizes global goals to end TB by 2035. Current diagnostic solutions depend on the detection of Mycobacterium tuberculosis (Mtb) in patient sputum, despite sputum's limitations as a diagnostic sample, making it difficult to obtain from patients with paucibacillary TB, such as those living with HIV (PLWH), young children, and patients with extrapulmonary TB. While rapid, sputum-based molecular diagnostics like GeneXpert (Cepheid, CA) are replacing slow, growth-based Mtb detection as the reference standard globally, most ATB is still diagnosed with sputum smear microscopy, despite its low sensitivity and specificity. Our long-term goal is to transform TB diagnosis for all age groups with a blood or urine test that accurately distinguishes patients with ATB from other pathologies, regardless of HIV co-infection. The objective of this study is to demonstrate the analytical and clinical performance of a novel assay that combines the sensitivity of our proof-of-principle bioelectrical TB (BET) assay with the ease of use of paper-based lateral flow immunoassays (LFAs) to create a highly novel electrochemical LFA (eLFA) for point-of-need TB detection. Our central hypothesis is that our proposed eLFA test will enable us to diagnose ATB with an accuracy that meets or exceeds the WHO Target Product Profile (minimum accuracy: 90% sensitivity and 70% specificity for a triage test for TB). We will achieve our objective through the following specific aims: AIM 1: Determine the operating characteristics of the eLFA using contrived samples and bio-banked blood from patients at risk for TB. We will obtain estimates of precision, cross-reactivity, and accuracy using GeneXpert and culture status as references. AIM 2: Determine the operating characteristics of the eLFA using contrived samples and bio-banked urine. We will obtain estimates of precision, cross-reactivity, and accuracy using GeneXpert, and culture status as references, along with a combination of contrived and clinical samples.