Background: Lack of knowledge of the identity of fungal allergens still is a major obstacle for improvement of diagnosis and therapy of allergies to moulds. We have therefore further analyzed the allergens of the two moulds, Alternaria alternata and Cladosporium herbarum and found that enolases (EC 4.2.1.11) are major allergens, at least of the two fungal species just mentioned.
Methods: The enolases of Alternaria and Cladosporium were cloned from cDNA libraries constructed from vegetative cells of the two moulds by immunological screening with sera from selected patients allergic to the moulds. The two enolases were expressed as recombinant nonfusion proteins and used for determination of the incidence of allergy to enolase among a cohort of patients.
Results: Sequencing of the two enolases showed very close relationships with other known fungal enolase sequences. Competition experiments using immunoblots of the recombinant nonfusion proteins showed nearly complete identity of the epitopes on both enolases. Serum from a patient reactive to Cladosporium enolase reacted equally well with the enolases of Alternaria, Saccharomyces and Candida. About 50% each of the sera from patients reactive to Cladosporium and Alternaria were strongly reactive to the recombinant enolases.
Conclusions: Enolases are therefore considered to be highly conserved major fungal allergens.