Surface antigenic determinant of epimastigote forms common to trypomastigote and amastigote forms of different strains of Trypanosoma cruzi.

A fraction (FA) has been isolated from the sediment obtained from Trypanosoma cruzi of epimastigote lysates centrifuged at 1500 x g, for 30 min. This fraction, obtained by extracting sediments, for 10 min, with ice-cold 0.1 N NaOH, exhibited a single component, a glycoprotein, when analysed by electrophoresis in 1% agarose gel and presented a single faint precipitation line in immunoelectrophoresis experiments. FA components were unable to penetrate polyacrylamide gel matrix, even when 1% SDS 4% polyacrylamide gels were used, unless previously hydrolyzed by parasite proteinase. Under this condition FA preparations presented at least four glycoproteins components as detected by electrophoresis in 1% SDS 15% polyacrylamide gels. FA obtained from Y strain was able to inhibit agglutination reactions between anti-epimastigote sera and epimastigote of either Y or Nic strains. Anti-FA antibodies, elicited in 4 out of 12 rabbits inoculated with this fraction, gave positive immunofluorescence and immunoperoxidase reactions with blood trypomastigota and tissue amastigota, obtained from mice infected with any of 6 different strains of T. cruzi. These reactions which were inhibited by FA preparations were completely abolished if antisera were absorbed with living epimastigota of Y or Nic strains.