Trypanosoma cruzi tubulin eliminated in the urine of the infected host

In previous studies we have identified and characterized an 80-kDa Trypanosoma cruzi urinary antigen (UAg) eliminated during acute infection. Polyclonal antibodies raised against this antigen revealed by western blotting and immunoprecipitation analyses showed the existence of another antigenic component of 50-55 kDa in the UAg preparation, The antiserum was also used for screening of a T. cruzi expression library. Sequencing of inserts from selected cDNA clones showed high homology with the 3' end of the T. cruzi beta-tubulin gene sequence encoding for the C-terminus of the protein. The presence of T. cruzi tubulin in the UAg was confirmed by immunoprecipitation of a 50-55-kDa protein from I-125-labeled UAg with monoclonal antibodies (MAbs) to human alpha/beta-tubulin. Interestingly, MAbs recognized radiolabeled T. cruzi tubulin eliminated in the urine of infected mice 24 hr postinoculation of [S-35]methionine-labeled viable trypomastigotes. Tubulin found in the urine proved to be of T. cruzi origin because this protein could not be identified in urinary specimens from uninfected animals or mice acutely infected with Leishmania infantum or Toxoplasma gondii We conclude that tubulin is one of the parasite antigens eliminated in the urine of T. cruzi-infected hosts. This finding may be used to develop a noninvasive procedure for early diagnosis of Chagas' disease.