DEVELOPMENT OF AN IFN-GAMMA RELEASE ASSAY WITH THE CAPACITY TO DIAGNOSE LATENT TUBERCULOSIS INFECTION

AMIANO NICOLAS; MARÍA PAULA MORELLI; NANCY TATEOSIAN; CANDELA MARTIN; CLAUDIO GALLEGO; ARMITANO RITA; STUPKA JUAN; PALMERO, DOMINGO; CIALLELLA LORENA; GRACIELA DE CASADO; JUAN L. IOVANNA; GARCIA VERONICA

Congreso; Reunión Anual de Biociencias 2021; 2021

Current IFN-γ release assays (IGRAs) cannot discriminate active from latent tuberculosis infection (LTBI). Previously, we demonstrated that IFNγ secretion against Rv2626c, a Mycobacteriumtuberculosis (Mtb) dormancy antigen, allows to discriminate LTBI subjects from healthy donors (HD) and tuberculosis (TB) patients.In this work we developed Diagnos-TB, a new IGRA that differentiates TB and LTBI by using a fusion protein (Fp) containing CFP10 and ESAT6 Mtb antigens plus Rv2626c protein. CFP10 and ESAT6proteins were cloned, expressed and purified in our laboratory. Diagnos-TB comprises four sterile tubes containing i) negative and ii) positive controls, iii) Fp and iv) Rv2626c proteins. Heparanizedwhole blood is cultured inside each tube during 16-24h and plasma IFNγ is then assayed by ELISA. According to the IFNγ levels measured, an individual can be diagnosed as a TB patient, a LTBI subject or a non-infected person. We first established the cut-off for the Fp tube that differentiated infected subjects (TB patients and QuantiFERON-QFT+PPD+ people without symptoms) from not infected individuals (QFT-PPD- subjects)(ROC analysis: Cut-off = 0.36 IU/mL, sensitivity 85.4%, specificity = 84.4%, Area = 0.9010, p