Accuracy of an immune diagnostic assay based on RD1 selected epitopes for active tuberculosis in a clinical setting: a pilot study

Clin Microbiol Infect. 2006 Jun;12(6):544-50. doi: 10.1111/j.1469-0691.2006.01391.x.


A previous case-control study reported that an in-vitro interferon (IFN)-gamma response to early secreted antigenic target (ESAT)-6 selected peptides was associated with active tuberculosis (A-TB). The objective of the present pilot study was to evaluate the diagnostic accuracy of this assay for TB disease in a clinical setting. An IFN-gamma ELISPOT assay was performed on samples from patients with suspected A-TB using two peptides selected from ESAT-6 protein and three peptides selected from culture filtrate 10 (CFP-10) proteins. The results were compared with those obtained by two commercially available assays approved for diagnosis of TB infection (T SPOT-TB and QuantiFERON-TB Gold) which use ESAT-6/CFP-10 (RD1) overlapping peptides. Sensitivity to the RD1 selected peptides was 70% (positive for 16 of 23 patients with microbiologically diagnosed A-TB) and specificity was 91% (positive for three of 32 controls). In contrast, the sensitivity and specificity were 91% and 59%, respectively, for T SPOT-TB, and were 83% and 59%, respectively, for QuantiFERON-TB Gold. The RD1 selected peptides assay had the highest diagnostic odds ratio for A-TB. Thus, the results suggest that an assay based on RD1 selected peptides has a higher diagnostic accuracy for A-TB in a clinical setting compared with commercially available assays based on RD1 overlapping peptides.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens, Bacterial / chemistry
  • Antigens, Bacterial / immunology*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / immunology*
  • Demography
  • Epitopes, T-Lymphocyte / chemistry
  • Epitopes, T-Lymphocyte / immunology*
  • Female
  • Humans
  • Immunoassay / methods
  • Immunoassay / standards*
  • Male
  • Middle Aged
  • Odds Ratio
  • Pilot Projects
  • Recombinant Fusion Proteins / immunology
  • Sensitivity and Specificity
  • Tuberculosis / diagnosis*
  • Tuberculosis / immunology


  • Antigens, Bacterial
  • Bacterial Proteins
  • CFP-10 protein, Mycobacterium tuberculosis
  • ESAT-6 protein, Mycobacterium tuberculosis
  • ESAT-6-CFP10 fusion protein
  • Epitopes, T-Lymphocyte
  • Recombinant Fusion Proteins