Discussion

Little is known about what proteins regulate intracellular development of Trypanosoma cruzi in the mammalian cell. The present investigation has studied and characterized the intracellular development of T. cruzi considering a chemical biology approach. We have identified, from a high content screening campaing, a small molecule capable of arresting the intracellular development of T. cruzi, seemingly without affecting parasite or host cell viability. The functional characterization of compound activity showed that: (i) the intracellular development arrest phenotype is not restricted to a host cell type; (ii) the compound is able to inhibit the replication of other T. cruzi strains belonging to different Tc groups of clinical relevance (Y, Sylvio X10/1 and CL Brener strain); (iii) the arrest can be reversed upon compound removal, at which point intracellular amastigotes resume their cycle, differentiating to trypomastigotes; (v) the compound did not show cytotoxicity for distinct host cells (U2OS, LLC-MK2, NRK-52E and BHK-51) for up to 200 µM for 48 h; and (vi) while the epimastigote form of T. cruzi can also be arrested without loss of viability, the compound displayed a concentration-dependent cidal activity against bloodstream forms of Trypanosoma brucei and promastigote forms of Leishmania donovani (DD8 strain), without causing arrest. Altogether, these results suggest that this compound acts via a regulator of cell cycle that can specifically cause arrest in T. cruzi and not in other trypanosomatids. Future experiments will focus on target deconvolution and molecular characterization of the target, aiming at unveiling the parasite proteins that regulate T. cruzi parasite cell cycle and intracellular development in the host cell.