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Betschart, Bruno

Nom
Betschart, Bruno
Affiliation principale
Fonction
Professeur.e émérite
Email
bruno.betschart@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/302

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  • Publication
    Accès libre
    The synthetic, oxidized C-terminal fragment of the Plasmodium berghei circumsporozoite protein elicits a high protective response
    (2000)
    Roggero, Mario A.
    ;
    Meraldi, Valentin
    ;
    López, José A.
    ;
    Eberl, Gérard
    ;
    Romero, Jackie C.
    ;
    Matile, Hughe
    ;
    Betschart, Bruno 
    ;
    Corradin, Giampietro
    ;
    Renggli, John
    A polypeptide of 69 amino acids (PbCS 242-310) encompassing the C-terminal region of the circumsporozoite protein of Plasmodium berghei (PbCS) was generated using solid-phase peptide synthesis. The immunological and protective properties of peptide PbCS 242-310 were studied in BALB/c mice (H-2d). Two subcutaneous injections, in the presence of IFA at the base of the tail, generated (i) high titers of anti-peptide antibodies which also recognized the native P. berghei CS protein, (ii) cytolytic T cells specific for the Kd-restricted peptide PbCS 245-253 and (iii) partial CD8+-dependent protection against sporozoite-induced malaria. The same frequencies of peptide PbCS 245-253 specific CD8+ T cells were found by IFN-γ ELISPOT in the draining lymph nodes of animals immunized with the short optimal CTL peptide 245-253 or with the polypeptide 242-310, indicating that the longer polypeptide can be processed and presented in vivo in the context of MHC class I as efficiently as the short CTL peptide. Interestingly, higher levels of IFN-γ producing CD8+ T cells and protection were observed when the four cysteine residues present in the C-terminal peptide were fully oxidized. These findings underline the potential importance of the chemical nature of the C-terminal fragment on the activation of the immune system and concomitant protection.
  • Publication
    Accès libre
    Elimination of P. berghei liver stages is independent of Fas (CD95/Apo-I) or perforin-mediated cytotoxicity
    (1997)
    Renggli, J.
    ;
    Hahne, M.
    ;
    Matile, Hughe
    ;
    Betschart, Bruno 
    ;
    Tschopp, J.
    ;
    Corradin, Giampietro
    Immunization of mammals with irradiated malaria sporozoites protects from a subsequent contact with the parasite. Protective immunity is directed against the pre-erythrocytic stages of the parasite, sporozoites and liver stages. Specific antibodies neutralize part of the infectious sporozoites injected by the mosquito vector, while liver stages are the target of a cellular immune response which is mediated by T cells. In this study, we evaluated the T-cell dependent protection induced by the injection of P. berghei irradiated sporozoites and the contribution of perforin and of the receptor/ligand system CD95/CD95L, two T cell-dependent mechanisms known to mediate elimination of target cells. Wild type, perforin deficient, CD95 mutant, CD95L mutant and perforin deficient/CD95L mutant mice were immunized with P. berghei irradiated sporozoites and submitted to a challenge with infectious sporozoites. All mice immunized with P. berghei irradiated sporozoites were protected against a sporozoite challenge, including perforin deficient/CD95L mutant animals. These results indicate that T cells do not kill malaria-infected hepatocytes via one of the known pathways, but rather that activated parasite-specific T cells produce cytokines which activate in cascade other mechanisms responsible for the intracellular elimination of the parasite.