Aptamer against mannose-capped lipoarabinomannan inhibits virulent Mycobacterium tuberculosis infection in mice and rhesus monkeys.

The major surface lipoglycan of Mycobacterium tuberculosis (M. tb), mannose-capped lipoarabinomannan (ManLAM), is an immunosuppressive epitope of M. tb. We used systematic evolution of ligands by exponential enrichment (SELEX) to generate an aptamer (ZXL1) that specifically bound to ManLAM from the virulent M. tb strain H37Rv. Aptamer ZXL1 had the highest binding affinity, with an equilibrium dissociation constant (Kd) of 436.3 ± 37.84 nmol/l, and competed with the mannose receptor for binding to ManLAM and M. tb H37Rv. ZXL1 significantly inhibited the ManLAM-induced immunosuppression of CD11c(+) dendritic cells (DCs) and enhanced the M. tb antigen-presenting activity of DCs for naive CD4(+) Th1 cell activation. More importantly, we demonstrated that injection of aptamer ZXL1 significantly reduced the progression of M. tb H37Rv infections and bacterial loads in lungs of mice and rhesus monkeys. These results suggest that the aptamer ZXL1 is a new potential antimycobacterial agent and tuberculosis vaccine immune adjuvant.