IgE-mediated anaphylaxis caused by bites of the pigeon tick Argas reflexus: cloning and expression of the major allergen Arg r 1.
BACKGROUND
Anaphylactic reactions caused by bites of the European pigeon tick Argas reflexus are repeatedly reported. This soft-backed tick is a parasite of wild pigeons colonizing urban buildings and houses. Occasionally the ticks can bite human beings, inducing anaphylactic reactions in sensitized patients.


OBJECTIVE
Our aim was to characterize the major allergen implicated in a series of anaphylactic reactions caused by Argas bites and to produce the allergen as recombinant protein for diagnostic purposes.


METHODS
Protein extracts were prepared from whole A reflexus bodies, and IgE immunoblots were performed with sera from 13 patients who had an anaphylactic reaction with pigeon tick bites. A cDNA expression library was constructed from whole ticks and screened with a polyclonal rabbit antiserum raised against the major allergen.


RESULTS
The cDNA coding for the dominant allergen Arg r 1 could be isolated. It encodes a protein belonging to the lipocalin family. Allergenicity of the recombinant Arg r 1 was confirmed by immunoblot, ELISA, and intradermal skin tests.


CONCLUSIONS
The dominant allergen of A reflexus has been isolated and the corresponding cDNA cloned. The recombinant protein, a lipocalin, was expressed in Escherichia coli and was shown to be immunoreactive in vitro and in vivo. Recombinant Arg r 1 was used as a diagnostic tool in a series of anaphylactic reactions caused by pigeon tick bites.
Hilger
Christiane
C
Centre de Recherche Public-Santé/Centre Hospitalier de Luxembourg, Laboratory of Immunogenetics and Allergology, Luxembourg. christiane.hilger@crp-sante.lu
Bessot
Jean-Claude
JC
Hutt
Nicolas
N
Grigioni
Fabienne
F
De Blay
Frédéric
F
Pauli
Gabrielle
G
Hentges
François
F
D000485:Allergens / Q000276:immunology / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D000707:Anaphylaxis / Q000209:etiology*; D000818:Animals; D026864:Argas / Q000235:genetics / Q000276:immunology*; D001733:Bites and Stings / Q000150:complications*; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D015723:Gene Library; D006801:Humans; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000276:immunology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology*; D017385:Sequence Homology
D000485:Allergens; D011994:Recombinant Proteins; D007073:Immunoglobulin E