Abstract: Using the Cr PI clone from the λEXcell library as a template, the cDNA fragments were first generated by PCR techniques and then ligated into T vector. After being confirmed by DNA sequencing, the cDNA encoding the American cockroach Cr PI allergen was subcloned into pGEX-5X-1 and expressed as GSTfusion protein in the form of inclusion bodies. After being dissolved in 6 mol/L guanidine hydrochloride and renatured with a simple dilution method, the proteins of target were purified to above 90% purity by affinity chromatography with Glutathione Sepharose 4B. Tested with sera from subjects allergic to cockroach, the recombinant allergen was shown to possess good IgEbinding activity as determined by Western blotting.

Key words: American cockroach, Periplaneta americana, recombinant allergen Cr PI, protein expression, affinity chromatography, Western blotting