[Partial purification and use of Trypanosoma cruzi glycosidic fractions for Chagas disease diagnosis]. / Purificación parcial y empleo de fracciones glicosídicas de Trypanosoma cruzi en el diagnóstico de la enfermedad de Chagas.

Protein and glycoprotein fractions are used for Chagas' disease diagnosis, but they are degraded by parasite endogenous proteases. Therefore protease inhibitors are used for their conservation increasing the antigen cost. The possibility of using protease-resistant glycosidic fractions could solve this problem allowing to obtain stable antigens, with a high sensitivity at a lower cost. This proposal is reinforced by the existence of anti-galactosyl antibodies against T. cruzi oligosaccharic fractions in sera from chagasic patients. The aim of this work was to obtain T. cruzi glycosidic fractions and to evaluate their possible use for Chagas' disease serologic diagnosis. Total protein and glycoproteins from the four stages of T. cruzi were obtained. The glycosidic fractions were obtained by exhaustive proteolysis with Proteinase K. Protein, glycoprotein and glycosidic profiles were analysed by SDS-PAGE followed by staining proteins (Coomassie/silver) or glycoproteins and glycosidic fractions (APABGP). Antigenicity of the different fractions was determined by Western Blot and luminography, using control hyperimmune serum anti-epimastigote and a "pool" of chagasic human sera. Finally, the capacity of the glycosidic fractions to discriminate chagasic and non-chagasic human sera and the sensitivity of the fractions respect to control serum, were determined by ELISA. Main findings were: a) there are peptides, glycopeptides and glycosidic fractions that are common and specific to parasite stages; b) there are more antigenic glycoproteins in epimastigotes and metacyclics than in trypomastigotes and amastigotes; c) there is a correlation between the glycosidic fraction-pattern and the host type; d) glycosidic fractions can be used as antigens to discriminate, by ELISA, chagasic and non chagasic patients, but show lower titers with respect to total proteic and glycoprotein antigens. It is concluded that it is possible to develop a diagnostic kit for Chagas' disease employing glycosidic fractions, eliminating the disadvantages of the current kits.

Contributions to the elucidation of S XIV pneumococcal polysaccharide structure.

Rabbits were immunized with a hemocyanin (Hcy)-p-amino phenyl beta lactoside (PAFBLO) conjugate and the gamma globulin fraction from immune sera was purified. Antibodies were demonstrated by means of the quantitative precipitin reaction using an egg albumin (EA)-PAFBLO conjugate as antigen. PAFBLO, D-lactose, D-galactose, cellobiose and D-galacturonic acid were used as inhibitors of the precipitin reaction and their relative affinity constants were calculated. The best inhibitors were the homologous hapten, D-lactose and D-galactose. Anti PAFBLO antibodies precipitated with types 6, 14 and 18 pneumococcal polysaccharides (SVI, SXIV and SXVIII) probably due to the presence of either D-lactose or D-galactose in similar linkage as in PAFBLO in these polymers. Antibodies also reacted with human red blood cells type B.

Characterization of antigens of the nematode Nippostrongylus brasiliensis by monoclonal antibodies.

Hybridomas secreting monoclonal antibodies to Nippostrongylus brasiliensis antigens were generated by hybridization of IR983F myeloma cells with spleen cells from Lou/M/Wol rats infected with living third-stage larvae. Antibodies specific either for larval or worm antigens were identified by enzyme-linked immunosorbent assays with Nippostrongylus brasiliensis fragments, homogenates and secretions as antigens. The results demonstrate that all antibodies which recognized larval antigens (38 antibodies) also reacted with worm surfaces. Ten antibodies were specific only for worm antigens. Ten antibodies reacted with worm homogenate, three antibodies recognized components of worm secretion and 17 antibodies combined with acetylcholinesterase. The epitope specificity was investigated by the capacity of various glycosides, aminoacids, N-acetylneuraminic acid and phosphorylcholine to inhibit the binding to worm fragments. The analysis revealed that alpha-methylglucoside, alpha-methylmannoside, N-acetylglucosamine, N-acetylgalactosamine, fucose and the amino acids leucine, phenylalanine, tyrosine, serine, tryptophan did not combine with the antigen-binding sites of the antibodies. Proline, arginine and histidine, however, displayed inhibitory effects. With N-acetylneuraminic acid as inhibitor three groups of antibodies could be discriminated. At a concentration of 10-20 mM, phosphorylcholine was a potent inhibitor for all antibodies.