RESUMO
OBJECTIVE: To clone and express Der f7 gene of Dermatophagoides farinae, and identify its immunogenicity. METHODS: Total RNA was extracted from D. farinae mites. A reference sequence (Accession No. AY283292) was used to design specific primers. The Der f7 gene fragment was amplified by RT-PCR, and cloned into pET-32a vector. The recombinant plasmid was transformed into E. coli BL21 (DE3) and induced with IPTG for protein expression. The recombinant protein was purified by Ni2+ chelating affinity chromatography and analyzed by SDS-PAGE and Western blotting. RESULTS: The Der f7 gene fragment was about 650 bp, and shared 99% homology with the published one (Accession No. FJ436108). SDS-PAGE result showed its relative molecular weight (M(r)) of 23 000. The recombinant protein showed appropriate combination ability with IgE in sera of mite allergic patients. CONCLUSION: Der f 7 gene has been expressed in prokaryotic expression system and shows allergenicity.
