AN IRON-BINDING TRYPANOSOMA-CRUZI URINARY ANTIGEN

An 80-kDa Trypanosoma cruzi urinary antigen (UAg) was affinity purifie d from the urine of infected dogs. We demonstrated that UAg is structu rally and functionally related to proteins belonging to the transferri n family, as shown by amino acid sequence and iron binding experiments . Nevertheless, monoclonal antibodies raised against UAg specifically and selectively recognized this parasite's circulating antigen. The ex istence of an 80-kDa T. cruzi antigen co-migrating with UAS could be c onfirmed when epimastigotes were metabolically labelled with [S-35] me thionine and then immunoprecipitated with the above mentioned antibodi es. We conclude that UAg is an iron-binding T. cruzi component elimina ted in the urine of the infected host.