GALACTOFURANOSE-CONTAINING GLYCOCONJUGATES OF EPIMASTIGOTE AND TRYPOMASTIGOTE FORMS OF TRYPANOSOMA-CRUZI

Antiserum to LPPG, a lipopeptidophosphoglycan originally described on the surface of Trypanosoma cruzi epimastigotes of the Y strain, and an tibodies to furanoic galactose (gal(f)) were obtained in rabbits. A mi cromethod for the extraction and purification of LPPG from a limited a mount of parasites is described. Analysis by Western blots of the puri fied glycoconjugate probed with both antisera confirmed the presence o f gal(f)-containing LPPG-like molecules in 10 different strains and cl ones of T. cruzi. An analogous approach indicated that trypomastigotes also contain LPPG-like components. Quantitation experiments allowed t o calculate an average value of 1.0 X 10(7) LPPG molecules per epimast igote cell and 0. 16 X 10(7) LPPG-like molecules per trypomastigote ce ll. Immunoelectron microscopy has shown a homogeneous distribution of LPPG on the surface of epimastigotes. The trypomastigote population, h owever, is highly heterogeneous with no more than 15% of the parasites being labeled by the anti-LPPG serum. Intense labeling has also been found in vesicles inside the epimastigote and trypomastigote forms. Th e distribution of gal(f) epitopes among glycoconjugates of epimastigot es and trypomastigotes was further investigated. It was shown that gal (f) units in epimastigotes are bound to low molecular mass compounds w hich co-migrate with LPPG whereas in trypomastigotes they have been fo und in both low molecular mass LPPG-like molecules and glycoproteins o f 80-90 kDa. Direct chemical evidence for the presence of gal(f) resid ues in the N-linked oligosaccharide chains of these surface glycoprote ins has been obtained. Finally, the natural antigenicity of LPPG and g al(f) in chronic Chagas' disease was investigated. It was found that a ll chronic chagasic sera investigated recognize this glycoconjugate an d that an important part of such recognition can be attributed to gal( f) residues. Furthermore, no correlation among reactivity to LPPG, str ain zymodeme and clinical forms of the disease was found.