Navegando por Palavras-chave "trans-sialidase"

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    Immune response to a major Trypanosoma cruzi antigen, cruzipain, is differentially modulated in C57BL/6 and BALB/c mice
    (Elsevier B.V., 2004-11-01) Guinazu, N.; Pellegrini, A.; Giordanengo, L.; Aoki, M. P.; Rivarola, H. W.; Cano, R.; Rodrigues, M. M.; Gea, S.; Univ Nacl Cordoba; Natl Univ Cordoba; Universidade Federal de São Paulo (UNIFESP)
    BALB/c mice immunized with cruzipain, a major Trypanosoma cruzi antigen, produce specific and autoreactive immune responses against heart myosin, associated with cardiac functional and structural abnormalities. Preferential activation of the Th2 phenotype and an increase in cell populations expressing CD19(+), Mac-1(+) and Gr-1(+) markers were found in the spleens of these mice. the aim of the present study was to investigate whether cardiac autoimmunity could be induced by cruzipain immunization of C57BL/6 mice and to compare the immune response elicited with that of BALB/c mice. We demonstrate that immune C57BL/6 splenocytes, re-stimulated in vitro with cruzipain, produced high levels of IFNgamma and low levels of IL-4 compatible with a Th1 profile. in contrast to BALB/c mice, spleens from cruzipain immune C57BL/6 mice revealed no significant changes in the number of cells presenting CD19(+), Mac-1(+) and Gr-1(+) markers. An increased secretion of TGFbeta and a greater number of CD4(+)TGFbeta(+) cells were found in immune C57BL/6 but not in BALB/c mice. These findings were associated with the lack of autoreactive response against heart myosin and a myosin- or cruzipain-derived peptide. Thus, the differential immune response elicited in C57BL/6 and BALB/c mice upon cruzipain immunization is implicated in the resistance or pathogenesis of experimental Chagas' disease. (C) 2004 Elsevier SAS. All rights reserved.
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    Immunologically relevant strain polymorphism in the Amastigote Surface Protein 2 of Trypanosoma cruzi
    (Elsevier B.V., 2007-07-01) Claser, Carla; Espindola, Noeli Maria; Sasso, Gisela; Vaz, Adelaide Jose; Boscardin, Silvia B.; Rodrigues, Mauricio M.; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    Several evidences suggest that the Amastigote Surface Protein-2 (ASP-2) of Trypanosonia cruzi is an important target for immunity during infection. Based on this, we considered it important to evaluate its strain polymorphism. Initially, we observed the presence of conserved cross-reactive epitopes in amastigotes of all parasite strains tested. in addition, the predicted amino acid sequences of the genes isolated from the cDNA of amastigotes of CL-Brener, Tulahuen, Colombian and G strains displayed a high degree of identity (> 80%) to the previously described C Genes of ASP-2. Unexpectedly, Sylvio X10/4 and G strains expressed a new isoform of ASP-2 with limited identity to the previously described genes, but with a high degree of identity when compared to each other. Immunological studies confirmed the presence of cross-reactive epitopes between recombinant proteins representing the different isoforms of ASP-2. However, the genetic vaccination of mice with the new isoform of asp-2 gene expressed by the G strain failed to provide the same degree of protective immunity to a challenge by parasites of the Y strain as did asp-2 genes of Y or CL-Brener strains. in summary, we found that few strains can express different isoforms of ASP-2 which may not share cross-protective epitopes. (c) 2007 Elsevier Masson SAS. All rights reserved.
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    Observations on chemical and enzymatic approaches to alpha-2,3-sialylated octyl beta-lactoside
    (Elsevier B.V., 2002-04-15) Turnbull, W. B.; Harrison, J. A.; Kartha, KPR; Schenkman, S.; Field, R. A.; Univ St Andrews; Universidade Federal de São Paulo (UNIFESP)
    A comparison of chemical and chemo-enzymatic syntheses of alpha-2,3-sialylated octyl lactoside is reported. the chemical approach, starting from lactose and sialic acid, required 14 steps and proceeded in 5% overall yield; poor a-selectivity in the sialylation step necessitated a difficult and low yielding separation of anomers. A chemoenzymatic approach, employing recombinant Trypanosoma cruzi trans-sialidase to effect the key sialylation reaction, required 10 steps and gave a similar overall yield. Whereas the chemo-enzymatic synthesis required only three chromatographic purification steps overall, the chemical synthesis required at least nine. (C) 2002 Elsevier B.V. All rights reserved.