ROP-ESAT6-CFP10 as Tuberculosis-Specific Antigen in Interferon Gamma Release Assay

Abstract

Objective. The ROP-ESAT6-CFP10 antigen (Changzhou Niujin Shisong Biotech [CBI], China) was recently developed using recombinant overlapping peptide (ROP) technology. We used ROP-ESAT6CFP10 as a tuberculosis (TB)-specific antigen and compared it with existing interferon-gamma release assays (IGRAs). Methods. Healthy volunteers and patients who were diagnosed with TB within a one-year period were enrolled. Samples were tested with QuantiFERON-TB Gold (QFT; QIAGEN Sciences Inc., USA), T-SPOT.TB (Oxford Immunotec, UK), and ELISpot using ROP-ESAT6-CFP10 as a TB-specific antigen (ROP-TB). For ROP-TB, two concentrations (1 i.tg and 5 i.tg) of ROP-ESAT6-CFP10 were used as TB-specific antigens. Agreement between assays was evaluated. Results. A total of 35 TB patients and 20 healthy volunteers were evaluated. Agreement between T-SPOT.TB and ROP-TB 1 i.tg, QFT and ROP-TB 1 i.tg, and ROP-TB 1 i.tg and ROP-TB 5 i.tg/mL were 79.1% (kappa=0.483), 76.7% (kappa=0.557), and 95.3% (kappa=0.894), respectively. The median number of spots between the T-SPOT.TB and ROP-TB assays in the TB patients had no significant difference. Conclusions. ELISpot using newly developed ROPESAT6-CFP10 showed good agreement with T-SPOT.TB and QFT. Since ROP technology can lower the manufacturing cost, ROP-ESAT6-CFP10 might work as a good source of TB-specific antigen for IGRAs.