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Purification and characterization of a major cross-reactive allergen from Epicoccum purpurascens
Vandana Bisht1, Naveen Arora, B P Singh
1Institute of Genomics and Integrative Biology, Delhi University Campus, Delhi, India.
Background:
Epicoccum purpurascens (formerly nigrum) (EP), is a ubiquitous saprophytic mould found both indoors and outdoors. Several studies have reported sensitization to EP in 5-7% of different populations worldwide. The diagnosis of mould allergy requires a standardized fungal extract that contains all its important allergenic proteins. The crude allergen extract from EP was standardized earlier, however none of its allergens have been purified.
Methods:
A major allergen from spore-mycelia extract of EP was purified using concanavalin A (Con A) Sepharose chromatography, gel filtration and electro-elution. The allergen isolated was characterized for its IgE-binding ability and cross-reactivity with five well-known allergenic fungi by ELISA and immunoblot.
Results:
A 33.5-kD glycoprotein allergen of EP, Epi p 1, was purified to homogeneity. All the EP allergic patients' sera tested recognized this protein. Periodate modification of Epi p 1 showed partial loss in IgE binding while proteinase K treatment caused complete loss in binding to IgE. Dose-dependent inhibition in binding of rabbit anti Epi p 1 antibodies was obtained with Epi p 1, Aspergillus fumigatus, Alternaria alternata, Curvularia lunata, Cladosporium herbarum and Fusarium solani in ELISA. Rabbit antibodies to all the above five fungi recognized Epi p 1 in immunoblot, confirming that Epi p 1 shares common epitopes with the fungi tested.
Conclusion:
A major glycoprotein allergen of 33.5 kD was purified from EP which cross-reacts with other fungi. Hence this glycoprotein can be exploited to reduce the panel of allergen extracts used for therapy of mould allergy.
Insights
A major allergen, Epi p 1 (33.5 kD glycoprotein), was purified from Epicoccum purpurascens mould. This purified allergen demonstrates cross-reactivity with other common fungi, offering potential for improved mould allergy diagnostics and therapies.
Area of Science:
- Mycology
- Immunology
- Allergology
Background:
- Epicoccum purpurascens (EP) is a common mould causing allergies in 5-7% of global populations.
- Standardized fungal extracts are crucial for diagnosing mould allergies, but EP allergens remain unpurified.
Purpose of the Study:
- To purify and characterize a major allergen from Epicoccum purpurascens.
- To investigate the IgE-binding properties and cross-reactivity of the purified allergen.
Main Methods:
- Purification of a major allergen using Concanavalin A Sepharose chromatography, gel filtration, and electro-elution.
- Characterization via ELISA and immunoblotting to assess IgE binding and cross-reactivity with other fungal allergens.
Main Results:
- A 33.5 kD glycoprotein allergen, Epi p 1, was purified to homogeneity from EP.
- Epi p 1 was recognized by sera of EP-allergic patients and showed IgE binding sensitive to periodate and proteinase K.
- Epi p 1 demonstrated cross-reactivity with Aspergillus fumigatus, Alternaria alternata, Curvularia lunata, Cladosporium herbarum, and Fusarium solani.
Conclusions:
- A major 33.5 kD glycoprotein allergen, Epi p 1, was isolated from EP.
- Epi p 1 shares common epitopes with other allergenic fungi, indicating cross-reactivity.
- This purified glycoprotein holds potential for simplifying allergen extract panels in mould allergy therapy.
