An Experimental Approach for the Identification of Conserved Secreted Proteins in Trypanosomatids

Abstract

Extracellular factors produced byLeishmania spp., Trypanosoma cruzi,andTrypanosoma bruceiare important in the host-parasite relationship. Here, we describe a genome-based approach to identify putative extracellular proteins conserved among trypanosomatids that are likely involved in the classical secretory pathway. Potentially secreted proteins were identified by bioinformatic analysis of theT. cruzigenome. A subset of thirteen genes encoding unknown proteins with orthologs containing a signal peptide sequence inL. infantum, L. major,andT. bruceiwere transfected intoL. infantum. Tagged proteins detected in the extracellular medium confirmed computer predictions in about 25% of the hits. Secretion was confirmed for twoL. infantumorthologs proteins using the same experimental system. Infectivity studies of transgenicLeishmaniaparasites suggest that one of the secreted proteins increases parasite replication inside macrophages. This methodology can identify conserved secreted proteins involved in the classical secretory pathway, and they may represent potential virulence factors in trypanosomatids.