Credit Card-Sized Test Boosts TB Detection in HIV Hotspots

Current tuberculosis (TB) tests face major limitations when it comes to accurately diagnosing the infection in individuals living with HIV. HIV, a frequent co-infection with TB, complicates detection by eliminating the very immune cells that many traditional TB tests depend on to flag the infection. While over 90% of the estimated 2 billion global TB cases remain latent—showing no symptoms and posing no transmission risk—the compromised immune systems of HIV-positive individuals can cause latent TB to become active. This transformation significantly raises the risk of further transmission and frequently leads to fatal outcomes. In fact, TB stands as the primary cause of death among people with HIV across the globe. Now, a newly developed handheld diagnostic tool offers a major advancement, significantly improving TB detection in HIV-infected individuals, according to research published in Nature Biomedical Engineering.

The portable device, developed at Tulane University (New Orleans, LA, USA), operates without electricity and is driven by a beetle-inspired chemical reaction. It addresses a persistent gap in the detection of TB among HIV-positive individuals, a gap that has long hindered global TB eradication efforts. To overcome the limitations posed by HIV-related immune suppression, researchers identified two new biomarkers that can reveal TB infection independently of the immune cells typically targeted by the virus. Named ASTRA (Antigen-Specific T-cell Response Assay), this compact, credit card-sized device requires just a single drop of blood and can deliver same-day diagnostic results without the need for laboratory infrastructure or skilled technicians. Once a drop of blood is added, the test must incubate for four hours, during which a built-in reagent stimulates immune cells. This reagent acts like a “wanted poster,” prompting the immune cells to respond if they’ve previously encountered TB bacteria.

To eliminate the need for electricity, researchers took inspiration from the bombardier beetle, which defends itself by mixing two chemicals that produce a forceful spray. Similarly, the ASTRA device uses a pair of chemicals that react to push the sample through a microchip for final analysis. The test delivers results in approximately four hours, significantly faster than the commonly used IGRA (Interferon-Gamma Release Assay), which requires 24 hours, and the TB skin test, which can take two to three days to yield a diagnosis. The effectiveness of ASTRA was validated using blood samples from individuals in Eswatini, a country with high TB incidence and the world’s highest known HIV prevalence (27.3%). Compared to IGRA, ASTRA demonstrated 87% specificity in detecting TB among HIV-infected individuals, markedly outperforming IGRA’s 60%. The device also surpassed IGRA in detecting TB in patients without HIV, underscoring its broader diagnostic potential.

“Current tests such as the IGRA are cost-prohibitive or require access to facilities that resource-limited communities don’t have. If we are going to eliminate TB, we have to diagnose and treat as many infection cases as possible,” said senior author Tony Hu, PhD, Weatherhead Presidential Chair in Biotechnology Innovation at Tulane University and director of the Tulane Center for Cellular & Molecular Diagnostics. “The sooner you have a diagnosis, the sooner you can begin the process of determining proper treatment. TB is the No. 1 pathogen HIV patients worry about globally. If treatment is available, we should be working to kill these bacteria, latent or not.”

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