Biological effect of varying peptide binding affinity to BoLA-DRB3 2703 allele

Mallard B.A., Alizadeh Z., Karrow N., Wilkie B.N., Sharif S.. 2002. Biological effect of varying peptide binding affinity to BoLA-DRB3 2703 allele. In : Second international symposium on Candidate Genes for Animal Health (C.G.A.H), Montpellier, France, August 16-18th 2002 : abstracts. CIRAD, INRA. Montpellier : CIRAD, Résumé, 1 p. International Symposium on Candidate Genes for Animal Health. 2, Montpellier, France, 16 Août 2002/18 Août 2002.

Note générale : Session 2 : Mechanisms of defence against infections

Résumé : The major histocompatibility complex (MHC) class I and class II molecules bind selectively to different antigenic peptides and present peptides to T-cell receptors. In mice and humans, peptide binding affinity (low and high) to MHC II molecules influences T-helper 1/T-helper 2 responses by inducing distinctive cytokine expression. To examine the effects of peptide binding affinity to bovine MHC, the BoLA-DRB3*2703 allele, previously associated with mastitis in Canadian Holsteins, was extracted and purified from BoLA-DRB3*2703-transfected L929 cells. Self peptides (BoLA-DQ and bovine fibrinogen fragments) previously eluted from this allele and non-self peptides from the core region of ovalbumin (OVA), as well as VP2 and VP4 peptides from foot and mouth disease virus (FMDV) were used in competitive binding assays. Briefly, a self-peptide of BoLA-DQ with high binding affinity was biotinylated as the marker peptide to use in competitive binding with purified BoLA-DRB3*2703 molecules in the presence of various concentrations of competing peptides. Binding was detected using Western blotting and enhanced chemiluminescence. Binding affinity determined as IC50 (concentration of competing peptides required to inhibit 50% binding), ranged from 26 to >320 :M. Two OVA peptides (OVA 323-335, OVA 323-339) and one FMDV peptide (VP-4) bound with relatively high affinity; 26.92, 72.22 and 46.46 :M respectively. OVA peptides, 316-327 and 325-336, bound weakly (>320 :M) to BoLA-DRB3*2703, while OVA 322-332 and VP-2 did not bind to this allele. Presence of glutamic acid, isoleucine, and asparagine at positions 333-335 appeared to partly influence peptide binding, but accurate prediction of binding will require computer scoring algorithms to scan protein sources of putative peptide ligands. Additionally, T-cells from a BoLA-DRB3*2703 homozygous cow were stimulated in vitro and cell proliferation was determined using the above peptides and transfected L929 cells as antigen presenting cells. OVA peptides, but not VP-4, with high binding affinities were able to induce significant T-cell proliferation. T-cell cytokine (IFN-3 and IL-4) production following stimulation with these peptides is currently under investigation. (Texte intégral)

Mots-clés Agrovoc : peptide, immunisation, biologie moléculaire, expression des gènes

Classification Agris : L10 - Génétique et amélioration des animaux

Auteurs et affiliations

• Mallard B.A., University of Guelph (CAN)
• Alizadeh Z., University of Guelph (CAN)
• Karrow N., University of Guelph (CAN)
• Wilkie B.N., University of Guelph (CAN)
• Sharif S., University of Guelph (CAN)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/512027/)

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