Der-p2 (Dermatophagoides pteronyssinus) allergen-like protein from the hard tick Ixodes ricinus - a novel member of ML (MD-2-related lipid-recognition) domain protein family

Objective. Expression of the gene encoding Der-p2 allergen-like protein in the castor bean tick Ixodes ricinus is induced by blood intake. Tick Der-p2 allergen-like protein belongs to a diverse family of ML proteins that includes major allergens of house dust mites, human MD-2 or similar proteins from Drosophila melanogaster. In ticks, genes encoding proteins belonging to the ML protein family were identified, but their protein products have not been characterized yet. Methods. A gene encoding tick Der-p2 allergen-like protein was amplified from cDNA of engorged I. ricinus female using the gene-specific primers designed on a basis of partial sequences of related allergen-like genes. The tissue and state specific patterns of expression of the gene were analysed. The IgE binding activity of the produced recombinant protein was studied by use of ELISA. Results. Analysis of the expression pattern showed that the gene encoding the tick Der-p2 allergen-like protein is strongly induced by the bloodmeal in gut and haemolymph throughout all tick developmental stages. Der-p2 allergen-like protein possesses a putative lipid-binding site, according to the comparisons with the related proteins. The ability of tick Der-p2 allergen-like protein to bind immunoglobulin E (IgE) was revealed. Discussion. The presence of a putative lipid-binding domain in Der-p2 allergen-like protein and its ability to interact with IgE might indicate the involvement of the protein in the tick's immune response.