Antimicrobial activity of recombinant E. coli expressed chicken AvBD-2 and its mRNA expression in Indian native Aseel and Kadaknath chicken breeds

Avian β defensins (AvBD) are antimicrobial peptides that play a crucial role in the innate immune response in chickens. In the present study, chicken AvBD2 gene was cloned, expressed in E. coli system and the in vitro antimicrobial activity of recombinant peptide was evaluated. The entire mature peptide region of chicken AvBD2 region was amplified and cloned in pUC29 cloning vector. Further, the coding region was sub cloned in pET-28A expression vector. After transformation in E. coli cells, the peptide synthesis was induced and recombinant protein (7.7 kDa) was purified by using Ni-NTA affinity column. The recombinant chicken AvBD2 showed antibacterial activity against S. Pullorum. The minimum bactericidal concentration (MBC) of recombinant chicken AvBD2 evaluated by micro-broth dilution assay was 35 μg/ml. We also quantified the expression of AvBD2 transcript expression in day-old spleen tissue of Indian native chicken breeds(Aseel and Kadaknath) and White Leghorn. Measurable AvBD2 mRNA expression was found in thespleen of all three breeds. However, no significant difference was found in AvBD2 gene expression between native chickens and White Leghorn.