Diagnosis for Latent Tuberculosis Infection: New Alternatives

Abstract

Latent tuberculosis infection (LTBI) is a subclinical mycobacterial infection defined on the basis of cellular immune response to mycobacterial antigens. The tuberculin skin test (TST) and the interferon gamma release assay (IGRA) are currently used to establish the diagnosis of LTB. However, neither TST nor IGRA is useful to discriminate between active and latent tuberculosis. Moreover, these tests cannot be used to predict whether an individual with LTBI will develop active tuberculosis (TB) or whether therapy for LTBI could be effective to decrease the risk of developing active TB. Therefore, in this article, we review current approaches and some efforts to identify an immunological marker that could be useful in distinguishing LTBI from TB and in evaluating the effectiveness of treatment of LTB on the risk of progression to active TB.

Clinical evaluation of QuantiFERON®-TB Gold Plus directly compared with QuantiFERON®-TB Gold In-Tube and T-Spot®.TB for active pulmonary tuberculosis in the elderly

“…2 and Table 4). This result may be because CD8 T-cells in peripheral blood have responded to shorter peptides in the TB2 tube [10,38]. The high positivity rate observed with the QFT-Plus test among elderly active TB patients can be attributed partly to the response obtained with the TB2 tube of the test (Table 5).…”

“…The T-SPOT assay is based on the enzyme-linked immunospot (ELISPOT) technique, which measures the number of IFN-γ-producing T cells [9]. The QuantiFERON®-TB Gold Plus (QFT-Plus) assay, an enzyme-linked immunosorbent assay (ELI-SA)-based method, is the fourth-generation QFT replacing QuantiFER-ON®-TB Gold In-Tube (QFT-GIT) [10]. Compared to the previous QFTs, the QFT-Plus assay only uses peptides from ESAT-6 and CFP-10 for TB-specific T-cell activation.…”

“…Compared to the previous QFTs, the QFT-Plus assay only uses peptides from ESAT-6 and CFP-10 for TB-specific T-cell activation. Another notable difference in the QFT-Plus test is the addition of a separate TB2 tube, which induces both CD4 and CD8 T lymphocytes to secrete IFN-γ; in contrast, the TB1 tube included in the QFT-GIT test only induces CD4 T cells [10].…”

Mycobacterial heparin-binding hemagglutinin (HBHA)-induced interferon-γ release assay (IGRA) for discrimination of latent and active tuberculosis: A systematic review and meta-analysis

“…The whole process is not only expensive and time-consuming, but also affects timely isolation and treatment, and causes the spread of the Mtb infection. Since there are no early and accurate diagnostic tests currently available for detecting active TB and differentiate it from LTBI, immunodiagnostic biomarkers are urgently needed to monitor the progression from LTBI to clinical disease [9,28,29]. Studies [9,10,11,30,31] showed that one of the most promising biomarkers is HBHA.…”

Immunological Characterization of Proteins Expressed by Genes Located in Mycobacterium tuberculosis-Specific Genomic Regions Encoding the ESAT6-like Proteins

“…BCG vaccination also faces a problem in the diagnosis of TB by using the widely used antigenic preparation of M. tuberculosis known as the purified protein derivative (PPD), in the tuberculin skin test, due to the presence of the cross-reactive antigens [ 28 , 29 , 30 , 31 , 32 , 33 , 34 ]. It is expected that M. tuberculosis -specific antigens may overcome the problem of diagnostic inaccuracy associated with the use of PPD in BCG-vaccinated people [ 35 , 36 , 37 , 38 , 39 , 40 ]. Hence, studies have been conducted to identify M. tuberculosis -specific antigens with vaccine and diagnostic potentials [ 41 , 42 , 43 , 44 , 45 , 46 , 47 ].…”