These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Amino acid dimorphism and parasite immune evasion: cellular immune responses to a promiscuous epitope of Plasmodium falciparum merozoite surface protein 1 displaying dimorphic amino acid polymorphism are highly constrained.
    Author: Daubenberger CA, Nickel B, Ciatto C, Grütter MG, Pöltl-Frank F, Rossi L, Siegler U, Robinson J, Kashala O, Patarroyo ME, Pluschke G.
    Journal: Eur J Immunol; 2002 Dec; 32(12):3667-77. PubMed ID: 12516559.
    Abstract:
    Like most other surface-exposed antigens of Plasmodium falciparum, the leading malaria vaccine candidate merozoite surface protein (MSP)-1 contains a large number of dimorphic amino acid positions. This type of diversity is presumed to be associated with parasite immune evasion and represents one major obstacle to malaria subunit vaccine development. To understand the precise role of antigen dimorphism in immune evasion, we have analyzed the flexibility of CD4 T cell immune responses against a semi-conserved sequence stretch of the N-terminal block of MSP-1. While this sequence contains overlapping promiscuous T cell epitopes and is a target for growth inhibitory antibodies, three dimorphic amino acid positions may limit its suitability as component of a multi-epitope malaria vaccine. We have analyzed the CD4 T cell responses in a group of human volunteers immunized with a synthetic malaria peptide vaccine containing a single MSP-143-53 sequence variant. All human T cell lines and HLA-DR- or -DP-restricted T cell clones studied were exclusively specific for the sequence variant used for immunization. Competition peptide binding assays with affinity-purified HLA-DR molecules indicated that dimorphism does not primarily affect HLA binding. Modeling studies of the dominant restricting HLA-DRB1*0801 molecule showed that the dimorphic amino acids represent potential TCR contact residues. Lack of productive triggering of the TCR by MHC/variant peptide ligand complexes thus seems to be the characteristic feature of parasite immune evasion associated with antigen dimorphism.
    [Abstract] [Full Text] [Related] [New Search]