Abstract:Ticks transmit various diseases to livestocks and human beings. The research of tick has been shown to play a key medical and veterinary role in the spread of disease. To express glutathione peroxidase (HlGPx) from Hemaphysalis longicornis in Escherichia coli (E. coli) so as to provide basis for further studies. The glutathione peroxidase gene was amplified by PCR from adult ticks of Haemaphysalis longicornis cDNA prompted by EST library information. The TGA codon encoding selenocysteine was mutated into the universal cysteine codon TGC by site-directed mutagenesis. BL21(DE3)pLysS was transformed by the recombinant expression vector pGEX-4T-1 and expressed by IPTG induction.The expression and reactogenicity of recombinant protein were analyzed by SDS -PAGE and Western blotting, respectively. Finally, the full length cDNA encoding glutathione peroxidase from Hemaphysalis longicornis was obtained successfully, and the molecular mass of the expressed fusion protein was approximately 45 kDa. Western blotting with anti-GST antibodies assay confirmed that result. In conclusion the mutated HlGPx is expressed in E. coli and it can be used for further preparation of immune serum and functional analysis.