Abstract:

The objective of the study was to clone avian βdefensin10 (AvBD10) gene from duck liver. In addition, expression of recombinant AvBD10 protein in E. coli and determination of its antimicrobial activity were investigated. The mRNA of duck AvBD10 was cloned from liver of duck by RTPCR. The mRNA differential expression of the AvBD10 gene has been demonstrated across a panel of tissues in duck. The cDNA of duck AvBD10 was subcloned into pGEX6p1 vector to construct recombinant plasmid pGEXduck AvBD10. The recombinant plasmid was transformed into E. coli BL21 and the bacteria were induced with IPTG. The recombinant fusion protein was purified by affinity chromatograph. Antimicrobial activity and physiochemical characteristics of the recombinant fusion protein were measured by inhibition zone assay. The results showed that the cDNA of duck AvBD10 consist of 169 bp encoding 55 amino acids. The duck AvBD10 had the highest amino acid homology (85.5%) with the chicken AvBD10. It was shown that the mRNA of duck AvBD10 just expressed in the liver and kidney of ducks at all ages investigated. The molecular weight of recombinant duck AvBD10 protein is about 30 ku (accounted for approximately 34% of the total proteins). The recombinant duck AvBD10 protein exhibit expected antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, and Pasteurella multocida after purified. In conclusion, AvBD10 was cloned from duck liver. It was showed that the mRNA of duck AvBD10 expressed highly in the liver and kidney of duck at all ages investigated. The recombinant duck AvBD10 protein exhibit broadly antimicrobial activity, and the recombinant protein retained high antimicrobial activity under different temperatures and pH.

Key words: duck, AvBD10, recombinant protein, antibacterial activity