Another major issue is that of antigen discovery, and while a number of DNA vacines tested so far against Leishmania or T. cruzi have shown promise, we are still unsure if these are the best possible antigens, particularly since these parasites have relatively large genomes, and only a limited variety of antigens have been tested. The availability of the genome sequences of these parasites will without doubt be a key resource for genome-wide screenings for new protective antigens. A key lesson from the initial studies reviewed here [48, 51, 108] , together with other similar antigen discovery studies, seems to be that cellular localization and protein function are poor predictors of the antigenicity and protective efficacy of a protein. Alternative criteria should thus be used so that potent vaccine candidates are not missed, and the important development of genome-mining and bioinformatic tools is providing new tools for a more rational search of vaccine candidates [110] .