QuantiFERON-TB performance enhanced by novel Mycobacterium tuberculosis-specific antigens

Tuberculosis (TB) still remains one of the most relevant public health problems worldwide with high prevalence, morbidity and un-necessary mortality (1), with the need of appropriate and efficient diagnostic tools (1, 2). In this context, one of the most significant development during the past 100 years has been the introduction in the diagnostic armamentarium for TB of the the whole-blood based Interferon Gamma Release Assays (IGRAs) for the diagnosis of TB infection (2, 3). IGRAs, that in the commercial version have been developed in two different technology readout systems such as QuantiFERON®-TB Gold In-Tube test (QFT-G-IT, QIAGEN, Gaithersburg, US) and T-SPOT®.TB (Oxford Immunotec Ltd, Abingdon,UK), are based on the detection of a T-cell immune response towards RD1 antigens (ESAT-6, CFP-10, with the addition of the TB7.7 for QFT-G-IT only) (2, 3). IGRAs present typically a great specificity, as the antigens used in IGRAs are almost exclusively expressed by the Mycobacterium tuberculosis (MTB)-complex and are less likely to be confounded by prior BCG vaccination and/or exposure to non-tuberculous mycobacteria (NTM), with the exception of few NTM) (2, 3). However, the diagnostic sensitivity of IGRAs to diagnose TB infections in still suboptimal and varies greatly worldwide from 75% to 85% in HIV-negative active TB patients (4), especially under the background of high TB-burden (5).