Antigenic Analysis of Group I House Dust Mite Allergens Using Random Fragments of Der p I Expressed by Recombinant DNA Libraries

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Abstract
Antigenic regions of a major house dust mite allergen, Der p I, were identified by a recombinant DNA strategy employing the technique of random fragmentation. Fragments of cDNA coding for Der p I were produced by sonication and used to construct lambda gt 11 expression libraries. Analyses of recombinant fragments reactive with a rabbit anti-Der p I antiserum showed that the B cell determinants expressed in Escherichia coli were limited, with the majority (86%) of antigenic clones isolated mapping to the region comprising amino acid sequence position 60–80. To define antigenic regions of Der p I more precisely, selected overlapping fragments were subcloned into the expression vector pGEX-1. Dot blot immunoassay and immunoabsorption studies using individual fusion proteins revealed five regions – 34–47, 60–72, 82–99, 112–140, and 166–194 – to contain B cell determinants responsible for the antigenicity of recombinant Der p I. Absorption of the anti-serum with Dermatophagoides pteronyssinus extract removed reactivity to all fragments, whereas absorption with an extract from the related mite Dermatophagoides farinae removed reactivity to peptides containing residues 34–47, 60–72, and 166–194, but not 82–99 and 112–140. Similarly, rabbit anti-D. farinae reacted strongly with peptides containing residues 34–47, 60–72, and 166–194, but not residues 82–99 and 112–140 which again showed antigenic differences in these residues between the group I allergens.