1 Response to Rv2628 latency antigen associates with cured tuberculosis and remote infection

Interferon-gamma-release assays based on RD1 antigens have improved diagnosis of latent tuberculosis infection (LTBI). However, these tests cannot discriminate between recently-acquired infection (higher risk of progression to active tuberculosis) and remote LTBI. The objective of this study was to evaluate the interferon-gamma-T-cell responses to M. tuberculosis-DosR regulon-encoded antigens (latency antigens) compared with QuantiFERON TB-Gold In-tube (QFT-IT) in subjects at different stages of tuberculosis. We studied 16 individuals with remote LTBI and 23 with recent infection. We also analyzed 15 controls unexposed to M. tuberculosis, 50 with active tuberculosis and 45 patients with cured-tuberculosis. Results indicate that subjects with remote LTBI had significantly higher interferon-gamma whole blood responses to M. tuberculosis-latency antigen Rv2628 than individuals with recent infection, active tuberculosis and controls (p<0.003), whereas no significant differences between these groups were found for other latency antigens tested (Rv2626, Rv2627, Rv2031c, Rv2032). The proportion of responders to Rv2628 was 5-fold higher among QFT-IT-positive-individuals with remote infection than among those with recently-acquired infection. These data suggest tha