Purification and Characterization of a Cross-Reactive 45-kD Major Allergen of Fusarium solani

Abstract

Background:Fusarium solani (FS) is an important source of fungal allergen. A 45-kD major allergen of FS showed reactivity with patients’ sera sensitive to many fungi. Objectives: To purify and characterize a 45-kD common allergenic protein from FS, which may be useful for the diagnosis of and therapy for fungal allergy. Methods: FS culture filtrate extract was separated on SDS-PAGE; 45-kD protein was electroeluted and purified on C18 column using reverse-phase high-pressure liquid chromatography (rpHPLC). The purified protein was functionally and biochemically characterized by in vitro and in vivo methods. Results: The 45-kD protein showed a single peak on rpHPLC. The N-terminal amino acid sequence of this protein did not show homology to enolase or known fungal proteins. It showed cross-reactivity with Epicoccum nigrum, Curvularia lunata, Cladosporium herbarum and Alternaria alternata by ELISA and ELISA inhibition using rabbit antibodies raised against these fungi. IgE ELISA inhibition with patients’ sera positive to different fungi demonstrated allergenic cross-reactivity of the 45-kD protein with other fungal extracts. This 45-kD protein released a significant amount of histamine in FS-allergic patients. Conclusion: A cross-reactive 45-kD allergenic/antigenic protein was purified to homogeneity and characterized. It has prospects for use in allergen therapy.