Selected RD1 peptides for active tuberculosis diagnosis: comparison of a gamma interferon whole-blood enzyme-linked immunosorbent assay and an enzyme-linked immunospot assay.
We recently set up a gamma interferon (IFN-gamma) enzyme-linked immunospot assay (ELISPOT), using selected early secreted antigenic target 6 (ESAT-6) peptides, that appears specific for active tuberculosis (A-TB). However, ELISPOT is difficult to automate. Thus, the objective of this study was to determine if the same selected peptides may be used in a technique more suitable for routine work in clinical laboratories, such as whole-blood enzyme-linked immunosorbent assay (WBE). For this purpose, 27 patients with A-TB and 41 control patients were enrolled. Our WBE, using the already described selected peptides from ESAT-6 plus three new ones from culture filtrate protein 10, was performed, and data were compared with those obtained by ELISPOT. Using our selected peptides, IFN-gamma production, evaluated by both WBE and ELISPOT, was significantly higher in patients with A-TB than in controls (P < 0.0001). Statistical analysis showed a good correlation between the results obtained by WBE and ELISPOT (r = 0.80, P < 0.001). To substantiate our data, we compared our WBE results with those obtained by QuantiFERON-TB Gold, a whole-blood assay based on region of difference 1 (RD1) overlapping peptides approved for TB infection diagnosis. We observed a slightly higher sensitivity with QuantiFERON-TB Gold than with our WBE (89% versus 81%); however, our test provided a better specificity result (90% versus 68%). In conclusion, results obtained by WBE based on selected RD1 peptides significantly correlate with those generated by ELISPOT. Moreover, our assay appears more specific for A-TB diagnosis than QuantiFERON-TB Gold, and thus it may represent a complementary tool for A-TB diagnosis for routine use in clinical laboratories.
Goletti
Delia
D
Laboratorio di collegamento tra ricerca di base e clinica, Padiglione Del Vecchio, Istituto Nazionale per le Malattie Infettive Lazzaro Spallanzani, I.R.C.C.S., Roma 00149, Italy. d.goletti@tiscali.it
Vincenti
Donatella
D
Carrara
Stefania
S
Butera
Ornella
O
Bizzoni
Federica
F
Bernardini
Giuliana
G
Amicosante
Massimo
M
Girardi
Enrico
E
D000942:Antigens, Bacterial / Q000097:blood; D001426:Bacterial Proteins; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007371:Interferon-gamma / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood; D011993:Recombinant Fusion Proteins / Q000097:blood; D014397:Tuberculosis, Pulmonary / Q000097:blood / Q000175:diagnosis* / Q000276:immunology
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C093276:ESAT-6 protein, Mycobacterium tuberculosis; C505464:ESAT-6-CFP10 fusion protein; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D007371:Interferon-gamma