Expression and characterization of chicken avian beta-defensin 6.

The chicken β-defensin 6 (AvBD6) cDNA fragment was amplified by reverse transcription polymerase chain reaction(RT-PCR) from the bone marrow tissue of chicken. The complete nucleotide sequence of the gene contained a 204 bp open reading frame (ORF) encoding 68 amino acids. Phylogenetic tree analysis of AvBD genes and mouse beta defensin-6 showed that the gene shared the highest percentage of amino acid homology (62.7 %) with chicken AvBD7. The chicken AvBD6 gene was cloned into pGEX-6p-1 vector and a 32 ku protein recombinant protein was expressed in E. coli. The antimicrobial activity of the recombinant fusion protein was evaluated in vitro, which exhibited high antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, and Pasteurella multocida, but low antimicrobial activity against Escherichia coil, and no antimicrobial activity against Salmonell choleraesuis. The minimal inhibitory concentration (MIC) of the recombinant protein against above bacteria ranged from 31.25 μg/mL to 250 μg/mL.