Handheld Test Improves TB Detection in HIV Patients
More than 90% of the estimated 2 billion TB cases globally are latent.
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A portable diagnostic device that uses a beetle-inspired chemical reaction has shown improved detection of tuberculosis (TB) in individuals with HIV, according to research published in Nature Biomedical Engineering. The test, called the Antigen-Specific T-cell Response Assay (ASTRA), aims to address diagnostic limitations of existing TB tests, particularly in populations with high HIV prevalence.
Diagnostic challenge in HIV co-infection
More than 90% of the estimated 2 billion TB cases globally are latent, meaning they show no symptoms and are not contagious. In individuals with HIV, however, immune suppression can allow latent TB to become active, increasing disease transmission and mortality. TB is the leading cause of death among HIV-positive individuals.
Traditional TB tests such as the Interferon-Gamma Release Assay (IGRA) depend on immune cell responses that HIV can suppress, reducing test accuracy. This diagnostic gap poses a significant challenge for public health efforts in regions with high HIV incidence.
A new approach to TB testing
The ASTRA test was developed by researchers at Tulane University. Roughly the size of a credit card, the device is designed for low-resource settings. It requires just a drop of blood and does not need laboratory facilities or electricity to operate.
In comparative testing, ASTRA showed 87% specificity in detecting TB among HIV-positive individuals, significantly outperforming the 60% specificity of the IGRA. The device also performed well in HIV-negative individuals. Results are available in about four hours, offering a faster alternative to the 24-hour turnaround time of the IGRA and the two to three days required for the TB skin test.
Beetle-inspired mechanics
The ASTRA test incorporates a unique mechanism modeled after the bombardier beetle, which uses a chemical reaction to produce a defensive spray. The device mimics this process by combining two chemicals to propel the blood sample across a microfluidic chip. This enables the analysis without the need for powered components.
The test works by introducing a reagent that prompts immune cells to react if they recognize Mycobacterium tuberculosis, the bacterium that causes TB. Crucially, the method relies on two newly identified biomarkers that allow detection even when HIV has compromised the typical immune cell response.
Field validation
To evaluate the device’s effectiveness, researchers tested it on samples from a cohort in Eswatini, a country with one of the highest TB and HIV burdens globally. Eswatini has an HIV prevalence rate of 27.3%, making it a critical setting for assessing the utility of improved TB diagnostics.
As TB drug resistance becomes more widespread, the need for early and accurate diagnosis is increasingly urgent. Tools like ASTRA that enhance diagnostic capabilities in high-risk populations could play an important role in controlling disease spread.
Reference: Ning B, Chandra S, Pan Y, et al. Self-powered rapid antigen-specific T-cell response assay for Mycobacterium tuberculosis infections. Nat Biomed Eng. 2025. doi:10.1038/s41551-025-01441-5
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