A new method of screening for latent tuberculosis infection: Results from army recruits in Beijing in 2014.

Latent tuberculosis infection (LTBI) lacks diagnostic gold method. Effective method is important to the control of tuberculosis. IFN-γ responses in 600 military recruits were tested by ELISA using whole blood incubation with latent protein Rv2029c, Rv2659c and recombinant protein CFP10-ESAT6 (rCE) respectively. They also received tuberculin skin test. Their BCG vaccination status was recorded. When 30.7% (184/600) of recruits gave higher IFN-γ responses (≥470pg/mL) to rCE as LTBI, the rests as healthy control, the AUC of rRv2029c was 0.856 and rRv2659c was 0.827 for LTBI diagnosis. IFN-γ responses to rCE were higher in PPD-positive group (≥5mm) than negative group (<5mm) (p<0.05), while for rRv2029c and rRv2659c were not (p>0.05). IFN-γ responses induced by rRv2029c and rRv2659c were higher in the moderately-positive group (≥5, <15mm) than the strongly-positive group (≥15mm) (p<0.05), while for rCE were not (p>0.05). IFN-γ levels to three antigens were not related to BCG vaccination status (p>0.05). Rv2659c and Rv2029c are good candidate antigens to complement the role of rCE for LTBI diagnosis, which provide a basis for developing cost-effective LTBI screening methods in the army.