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

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

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Congreso; Reunión Anual de Biociencias 2021; 2021

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) together with SARS-CoV-2 in2020-2021, was the leading cause of death from a single infectious agent. Furthermore, 1.9billion people worldwide are latently infected (LTBI) with Mtb. Identifying and treating LTBIconstitutes one of the most important impediments to control TB. Moreover, accurate tests todiagnosis LTBI are currently unavailable.We have previously demonstrated that circulating IgGagainst Rv2626c, an Mtb dormancy antigen, are found in plasma of LTBI. Then, here weevaluated particular regions of Rv2626c to be used to identify LTBI with higher sensitivity andspecificity. For this, we used peptides sequences derived from Rv2626c to sensitize ELISAplates and then we analyzed the levels of IgG antibodies against those peptides in LTBI, TBpatients and healthy donors (HD). The studied regions are overlapping synthetic peptides(13?15-mers, overlapped by 11amino acids; 36 in total) spanning the sequence of Rv2626c. Wefirst 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 highestpercentages of responders. Then, by investigating the specificity of the selected peptides, wecould observe that some of them presented a marked higher specificity as compared to HDand 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 and a percentage of responder individuals of 80% in LTBI,0% in HD, 1% in TB (**p