Recombinant allergen

Abstract

Dander from the domestic cat ( Felis domesticus ) is one of the most common causes of IgE mediated allergy. The present invention relates to a recombinant folded Fel d 1 with molecular and biological properties similar to the natural counterpart and specifically a synthetic gene coding for a direct fusion of Fel d 1 chain 2 N-terminally to chain 1. E coli expression resulted in a non-covalently associated homodimer with an apparent molecular weight of 30 kDa defined by size exclusion chromatography, each 19177 Da subunit displayed a disulfide pattern identical to that found in the natural Fel d 1, and having identical fold of natural and recombinant Fel d 1. The, recombinant Fel d 1 provides for diagnosis and allergen specific immunotherapy of cat allergy.

1 - 21 . (canceled) 
     
     
         22 . A recombinant Fel d 1 fusion product comprising a Fel d 1 chain 1, a Fel d 1 chain 2 and a linker selected from a carbon-nitrogen bond or a peptide linker having from 1 to 9 amino acid residues which links the N-terminal amino acid of one chain to the C-terminal amino acid of the other chain. 
     
     
         23 . A fusion product as claimed in  claim 22 , wherein the linker links the N-terminal amino acid of the chain 1 to the C-terminal amino acid of the chain 2. 
     
     
         24 . A fusion product as claimed in  claim 22  or  23 , wherein the linker is a carbon-nitrogen bond. 
     
     
         25 . A fusion product as claimed in  claim 22  or  23 , wherein the short peptide has from 1 to 5 amino acid residues and preferably from 1 to 3 amino acid residues. 
     
     
         26 . A fusion product as claimed in  claim 22 , wherein the linker comprises a target site for a reagent capable of selective cleavage of the linker. 
     
     
         27 . A fusion product as claimed in  claim 26 , wherein the reagent is an enzyme. 
     
     
         28 . A fusion product as claimed in  claim 22 , wherein the chain 1 and the chain 2 are covalently bonded together by one or more disulfide bridges into an antiparallel arrangement. 
     
     
         29 . A fusion product as claimed in  claim 22 , wherein the Fel d 1 chain 1 comprises a sequence of SEQ ID NO 1, or a homologue or fragment thereof which provides substantially the same allergenic properties as SEQ ID NO 1. 
     
     
         30 . A fusion product as claimed in  claim 22 , wherein the Fel d 1 chain 2 comprises a sequence of SEQ ID NO 2, SEQ ID NO 3, or a homologue or fragment thereof which provides substantially the same allergenic properties as SEQ ID NO 2 or SEQ ID NO 3. 
     
     
         31 . A fusion product as claimed in  claim 29  or  30 , wherein the homologue has greater than 90% homology, preferably greater than 95% homology and particularly preferably greater than 99% homology. 
     
     
         32 . A fusion product as claimed in  claim 22 , comprising a sequence of SEQ ID NO 4. 
     
     
         33 . A homodimer consisting of two non-covalently associated fusion products as claimed in  claim 22 . 
     
     
         34 . A DNA sequence encoding the fusion product as claimed in  claim 22 . 
     
     
         35 . An expression vector having the DNA sequence as claimed in  claim 34  inserted therein in an operable form. 
     
     
         36 . A host cell transformed with the expression vector as claimed in  claim 35 . 
     
     
         37 . A pharmaceutical composition comprising an immunotherapeutically effective amount of the fusion product as claimed in  claim 22  and/or the homodimer as claimed in  claim 33  and a pharmaceutically acceptable carrier, excipient or diluent. 
     
     
         38 . A kit for the diagnosis of cat allergy comprising the fusion product as claimed in  claim 22  and/or the homodimer as claimed in  claim 33  and instructions for use of the kit. 
     
     
         39 . A method for diagnosing cat allergy comprising the step of combining a sample taken from a subject with the fusion product as claimed in  claim 22  and/or the homodimer as claimed in  claim 33 . 
     
     
         40 . A process for preparing a fusion product as claimed in  claim 22  comprising the step of culturing the host cell as claimed in  claim 36  in a suitable medium. 
     
     
         41 . A process for preparing a recombinant Fel d 1 polypeptide comprising the steps of synthesising the fusion product as claimed in  claims 26  or  27  and selectively cleaving the linker.