Circulating IgG antibodies against immunodominant regions of the dormancy antigen Rv2626c discriminate latent tuberculosis infection.

AMIANO NICOLAS; ROCIO ZUAZO; MARIA PAULA MORELLI; NANCY L. TATEOSIÁN; CANDELA MARTIN; GALLEGO CLAUDIO; ARMITANO RITA; STUPKA JUAN; DE CASADO, GRACIELA C.; A LORENA CIALLELA,; DOMINGO J. PALMERO; IOVANNA, JUAN L.; GARCÍA VERÓNICA

Congreso; Reunión conjunta SAIC-SAI-AAFE-NANOMED.AR 2021; 2021

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) together with SARS-CoV-2 in 2020-2021, was the leading cause of death from a single infectious agent. Furthermore, 1.9 billion people worldwide are latently infected (LTBI) with Mtb. Identifying and treating LTBI constitutes one of the most important impediments to control TB control. Moreover, accurate tests to diagnosis LTBI are currently unavailable. We have previously demonstrated that circulating IgG against Rv2626c, an Mtb dormancy antigen, are found in plasma of LTBI. Then, here we evaluated particular regions of Rv2626c to be used to identify LTBI with higher sensitivity and specificity. For this, we used peptides sequences derived from Rv2626c to sensitize ELISA plates and then we analyzed the levels of IgG antibodies against those peptides in LTBI, TB patients and healthy donors (HD). The studied regions are overlapping synthetic peptides (13?15-mers, overlapped by 11 amino acids; 36 in total) spanning the sequence of Rv2626c. We first examined the levels of circulating IgG against each Rv2626c peptide in LTBI. By doing that, we identified 13 peptides that allow to detect elevated levels of antibodies in the highest percentages of responders. Then, by investigating the specificity of the selected peptides, we could observe that some of them presented a marked higher specificity as compared to HD and TB patients. For example A) with peptide 18 we observed D.O.LTBI = 0.45 ± 0.15, D.O.HD = 0.09 ± 0.02 and D.O.TB = 0.03 ± 0.01 (TB) and a percentage of responder individuals of 80% in LTBI, 0% in HD, 1% in TB (**p