Nuclear transport factor 2 represents a novel cross-reactive fungal allergen.
BACKGROUND
Ubiquitously occuring moulds are important allergenic sources known to elicit IgE-mediated allergic diseases and to share cross-reactive allergens. Limited information is available about the molecular structures involved in cross-reactivity. We aimed to clone and characterize cross-reactive mould allergens.


METHODS
Phage surface-displayed Alternaria alternata and Cladosporium herbarum cDNA libraries were screened using sera from Aspergillus fumigatus-sensitized patients. Inserts encoding putative allergens were sequenced, and recombinant proteins used to demonstrate cross-reactivity by inhibition experiments and skin test. Three-dimensional homology models of cloned putative nuclear transport factor 2 (NTF2) were constructed based on known NTF2 structure to corroborate the functional and structural properties of the novel allergens.


RESULTS
After six rounds of affinity selection, the libraries were enriched for clones displaying allergens. Sequencing of inserts showed that some clones derived from Alternaria alternata and Cladosporium herbarum contain open reading frames predicting proteins of 124 and 125 amino acids corresponding to NTF2. The recombinant proteins were able to bind and cross-inhibit IgE binding and to elicit type I skin reactions in mould-sensitized individuals, demonstrating the allergenicity of the proteins.


CONCLUSIONS
NTF2 represents a novel cross-reactive fungal allergen as demonstrated by sequence homology, three-dimensional modelling, inhibition experiments and skin test reactivity.
Weichel
M
M
Swiss Institute of Allergy and Asthma Research (SIAF), Obere Strasse 22, CH-7270 Davos, Switzerland.
Schmid-Grendelmeier
P
P
Flückiger
S
S
Breitenbach
M
M
Blaser
K
K
Crameri
R
R
D000485:Allergens / Q000276:immunology*; D000528:Alternaria / Q000235:genetics / Q000276:immunology*; D000595:Amino Acid Sequence; D000946:Antigens, Fungal / Q000276:immunology*; D002963:Cladosporium / Q000235:genetics / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D015723:Gene Library; D005800:Genes, Fungal; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D029543:Nucleocytoplasmic Transport Proteins / Q000276:immunology* / Q000302:isolation & purification; D011994:Recombinant Proteins; D017385:Sequence Homology; D012882:Skin Tests
D000485:Allergens; D000946:Antigens, Fungal; D029543:Nucleocytoplasmic Transport Proteins; D011994:Recombinant Proteins