Host Blood RNA Signatures for Diagnosis of TB (RADIANT)

Tuberculosis (TB) is the biggest infectious cause of death worldwide, and the biggest cause of death in Sub-Saharan Africa among HIV-positive patients. There is need for a non-sputum-based rapid triage test that identifies individuals with presumptive TB requiring confirmatory diagnostic investigation. Such a test could reduce the burden on health systems, expedite referral and confirmatory testing, and treatment thereby reducing transmission. A non-sputum triage test is needed as many symptomatic patients including those with HIV, can often not produce high quality sputum (which most current diagnostics rely on). Several blood transcriptional diagnostic signatures produced due to immune responses to M. tuberculosis infection have previously been described, however there is lack of real-world performance data especially in high TB/HIV-endemic African settings where rates of HIV (that could compromise sensitivity) and previous TB (that could compromise specificity) are high. Furthermore, by building on prior research that used untargeted sequencing approaches to identify candidate signatures, the investigators are now at a stage to perform the targeted signature measurement at a large scale and cost-efficient manner as part of prospective diagnostic accuracy analyses in real-world settings. Using the framework provided by an EDCTP-funded parent study (SeroSelectTB; PI Holm-Hansen), which is a pan-African evaluation of a point-of-care serological test for active TB, RADIANT has a unique opportunity to pursue several important research questions. RADIANT aims are to 1) evaluate the sensitivity and specificity of selected concise peripheral host transcriptional signatures for active TB among symptomatic persons (in South Africa=1260 and Tanzania=840); 2) design a cost-optimised diagnostic algorithm based on transcriptional signatures, SeroSelectTB results, and confirmatory bacteriological testing, and 3) characterise bacteriologically-negative patients classified as non-TB to determine if those with elevated host transcriptional signatures (n=100 expected) have other respiratory pathogens (detected in nasopharyngeal swabs using a commercial multiplex panel) and/or develop active TB within six months (incident active TB).