RESUMEN
We examined the expression and the antigenicity of the major surface polypeptides of Leishmania braziliensis braziliensis and Leishmania donovani chagasi, parasites which commonly coexist in the same endemic areas of Bolivia. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profiles from surface-iodinated promastigotes showed the presence of a unique iodinatable polypeptide of 72 kDa on the L. b. braziliensis surface and of two major components of 65 and 50 kDa exposed at the surface of L. d. chagasi. Comparison of the peptide digestion profiles of the major iodinated polypeptides of both strains showed no similarity between the maps of the 72- and the 65-kDa polypeptides of L. b. braziliensis and L. d. chagasi, respectively. Immunoprecipitation of surface-labeled L. b. braziliensis Nonidet P-40 extracts with 35 serum specimens obtained from Bolivian patients with cutaneous and mucocutaneous leishmaniasis showed that all serum specimens recognized predominantly the 72-kDa antigen and high-molecular-mass proteins in some cases. The recognition patterns were independent of the geographical origin of the patient, the type of lesion, and the serum antibody titer. Serum specimens from children with visceral leishmaniasis did not precipitate the L. b. braziliensis 72-kDa antigen. Hamster hyperimmune serum against L. b. braziliensis also recognized the 72-kDa surface antigen. However, this recognition was inhibited in the presence of the homologous nonlabeled antigen but not in the presence of heterologous (L. d. chagasi and Trypanosoma cruzi) antigens. The specific recognition of 72-kDa surface antigen in both natural and experimental L. b. braziliensis infections suggests that this antigen could be a good candidate for use in the differential immunodiagnosis and prognosis of the disease.
Asunto(s)
Antígenos de Protozoos , Antígenos de Superficie/aislamiento & purificación , Leishmania braziliensis/inmunología , Animales , Antígenos de Protozoos/química , Antígenos de Protozoos/aislamiento & purificación , Antígenos de Superficie/química , Cricetinae , Humanos , Leishmaniasis Mucocutánea/inmunología , Peso Molecular , Mapeo PeptídicoRESUMEN
This study describes the identification of aqueous-soluble antigens in Leishmania promastigotes immunologically and biochemically closely related to the major surface antigen. Proteins from surface-iodinated L. braziliensis braziliensis and L. donovani chagasi promastigotes, extracted and separated by partitioning in the detergent Triton X-114, were analyzed. Immunoblotting of the extracted proteins, using homologous antisera, showed recognition of a 72-kDa labeled, amphiphilic antigen of L. b. braziliensis and a 65-kDa surface antigen of L. d. chagasi. The respective homologous sera also recognized non-labeled hydrophilic antigens, similar in their apparent molecular weights to the major surface antigens. The amphiphilic and hydrophilic antigens of each species were found to share common antigenic determinants, inasmuch as monospecific antibodies that recognized the amphiphilic protein reacted with the hydrophilic antigen. Structural homology was also obtained in the peptide-digestion profiles of the amphiphilic and the respective hydrophilic major antigens. Zymogram assay showed that both amphibilic and hydrophilic fractions displayed proteolytic activity that could be directly attributed to the major L. b. braziliensis and L. d. chagasi antigens. The hydrophilic antigens found in this study are probably not hydrolytic products of the surface antigens and occur in large quantities in the promastigote cytosol.
Asunto(s)
Antígenos de Protozoos/análisis , Leishmania braziliensis/inmunología , Leishmania donovani/inmunología , Leishmania/inmunología , Animales , Antígenos de Protozoos/inmunología , Antígenos de Superficie/análisis , Antígenos de Superficie/inmunología , Reacciones Cruzadas , Citoplasma/inmunología , Electroforesis en Gel de Poliacrilamida , Humanos , Sueros Inmunes/inmunología , Immunoblotting , Leishmania braziliensis/enzimología , Leishmania donovani/enzimología , Péptido Hidrolasas/análisis , Péptido Hidrolasas/inmunología , Mapeo PeptídicoRESUMEN
In the present study, an enzymatical and structural analysis of Leishmania mexicana cell-surface components was carried out, demonstrating that protease and acid phosphatase activities were present at the L. mexicana cell surface. These findings correlate with the expression of the main components detected on the surface of L. mexicana promastigotes: the 50-kDa component is responsible for the acid phosphatase activity, whereas glycoprotein 65 (gp65) was characterized as the structural polypeptide of the surface protease. Furthermore, the 50- and 65-kDa antigens were found to be structurally different, inasmuch as no homology was observed in their peptide digestion profiles. The results presented in this communication confirm heterogeneity in the expression of the surface components of L. mexicana promastigotes at both the structural and the biochemical level.