Mapping of conformational IgE epitopes on Phl p 5a by using mimotopes from a phage display library.
BACKGROUND
Phl p 5 represents a major allergen of timothy grass pollen (Phleum pratense). Detailed knowledge about the structures responsible for IgE binding would allow the design of a novel generation of allergy vaccines.


OBJECTIVE
We aimed to characterize the IgE epitopes of Phl p 5a using phage display combined with a molecular modeling approach.


METHODS
Phl p 5a-specific IgE from sera of patients with grass pollen allergy was used for screening of a random peptide phage library displaying constrained decamers.


RESULTS
Fifteen phage clones that shared sequence motifs and could be grouped into families were selected by using Phl p 5a-specific IgE. Peptide alignment with the solvent-accessible amino acids of Phl p 5a revealed 3 sequence sections with frequent hits of identical or similar amino acids. On the surface of Phl p 5a, these sections assembled in compact patches, most likely representing conformational IgE epitopes, whereas no matching clusters were found on the back sides of the 2 Phl p 5a halves. In surface plasmon resonance experiments, the high-affinity interaction between IgE and Phl p 5 could be competed by phage-displayed peptides up to 24%, indicating that they represent true epitope mimics (ie, mimotopes). Allergen-specific immunogenicity of the mimotopes was proved in Biozzi mice.


CONCLUSIONS
The selected mimotopes facilitated the localization of conformational IgE epitopes of Phl p 5. We suggest them to be suitable candidates for the development of an epitope-specific immunotherapy.
Hantusch
Brigitte
B
Department of Patophysiology, Medical University of Vienna, Vienna, Austria.
Krieger
Sigurd
S
Untersmayr
Eva
E
Schöll
Isabella
I
Knittelfelder
Regina
R
Flicker
Sabine
S
Spitzauer
Susanne
S
Valenta
Rudolf
R
Boltz-Nitulescu
George
G
Scheiner
Otto
O
Jensen-Jarolim
Erika
E
D000595:Amino Acid Sequence; D000818:Animals; D018604:Epitope Mapping; D018985:Epitopes, B-Lymphocyte; D007073:Immunoglobulin E / Q000276:immunology*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019151:Peptide Library; D010940:Plant Proteins / Q000276:immunology*; D011487:Protein Conformation
D018985:Epitopes, B-Lymphocyte; D019151:Peptide Library; C076049:Phl p V protein, Phleum pratense; D010940:Plant Proteins; D007073:Immunoglobulin E