Potential novel markers to discriminate between active and latent tuberculosis infection in Chinese individuals.

Latent tuberculosis infection (LTBI) constitutes the main reservoir for reactivation tuberculosis. The finding of potential biomarkers for differentiating between TB and LTBI is very necessary. In this study, the immunological characteristics and potential diagnostic utility of Rv2029c, Rv2628 and Rv1813c proteins were assessed. These three proteins stimulated PBMCs from ELISPOT-positive LTBI subjects produced higher levels of IFN-γ in comparison with TB patients and ELISPOT-negative healthy subjects (p<0.05). BCG vaccination and non-TB respiratory disease had little influence on the immunological responses of Rv2029c and Rv2628 proteins (p>0.05). The LTBI diagnostic performance of Rv2029c was higher than Rv2628 and Rv1813c by ROC evaluation. But Rv2628 had much higher specificity than Rv2029c in active TB patients and uninfected healthy subjects. The IgG level against Rv1813c was higher in the TB group than in LTBI and uninfected healthy subjects (p<0.05). These results suggest that T cell response to Rv2628 and antibody against Rv1813c might be applicable as biomarkers to distinguish TB from LTBI and uninfected individuals.