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

- The IFN-γ response to the latent protein Rv2029c and Rv2659c was specific for the LTBI population.
- The IFN-γ response to rCFP10-ESAT6, Rv2659c and Rv2029c were not related to BCG vaccination status.
- Rv2659c and Rv2029c are good candidate antigens to complement the role of rCFP10-ESAT6 for LTBI diagnosis.

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 (≥470 pg/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 (≥5 mm) than negative group (<5 mm) (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, <15 mm) than the strongly-positive group (≥15 mm) (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.