Accuracy of an immune diagnostic assay based on RD1 selected epitopes for active tuberculosis in a clinical setting: a pilot study.
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.
Goletti
D
D
Second Division of Health Department, National Institute for Infectious Diseases Lazzaro Spallanzani, Rome, Italy. d.goletti@tiscali.it
Carrara
S
S
Vincenti
D
D
Saltini
C
C
Rizzi
E Busi
EB
Schininà
V
V
Ippolito
G
G
Amicosante
M
M
Girardi
E
E
D000328:Adult; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000276:immunology*; D003710:Demography; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000592:standards*; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010865:Pilot Projects; D011993:Recombinant Fusion Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; C505464:ESAT-6-CFP10 fusion protein; D018984:Epitopes, T-Lymphocyte; D011993:Recombinant Fusion Proteins