Isolation and characterization of allergens from curvularia lunata

Abstract

Curvularia is commonly present in the Singapore environments and found to cause sensitization in the atopic patients. This was in contrast with other European countries where Alternaria and Cladosporium are found to be predominant fungi. Apart from that, only allergens belonging to the genera Aspergillus/Penicillium and Alternaria are studied in detail till date. In the present study, we concentrated on the identification and characterization of the allergens from Curvularia lunata using the sequence tagging and proteomic approaches. The obtained putative allergens were cloned/expressed in E.coli and purified. Purified recombinant allergens along with their corresponding homologs from Penicillium, Aspergillus, Alternaria, Saccharomyces, Human and Mouse were cross-compared for IgE binding by immuno blots using patients` sera from 4 different populations varying geographically as well as specific allergen sensitivities. Further inhibition studies carried out with the corresponding homologs showed majority of these proteins to be cross-reactive with their respective homologs. Cross-reactivity was also supported by the observed conservation of amino acid as well as 3D structures. Exposure levels of C.lunata allergens were detected in the outdoor environment as well as in the house dusts. All these data suggest that C.lunata is an important allergenic fungus. Furthermore, cross-reactivity of the fungal allergens with the corresponding human homologs suggests possible auto-reactivity of endogenous proteins to the environmental (fungal) allergens. Hence, study of these recombinant allergens will help in better understanding of fungal allergens and will aid in the development of specific allergen based immunotherapy.