The Antimicrobial Potential Of Chicken AvBD6Screened On The Basis Of Salmonella Resistance

Salmonella pullorum is one of the most serious intestinal bacteria. Screening advantage chicken β-defensins which can resist Salmonella pullorum infection by studying expression regulation in vivo is important.In this study, animal model of chickens infected with Salmonella pullorum was established to screen advantage chicken β-defensins, analyse the structure-activity of the advantage AvBD using bioinformatics software, and improve the biological selection activity by the molecular design. Specific details and results were as follows:1Expression screening of resisting against Salmonella pullorum of AvBD6The Roman chickens was inoculated with Salmonella pullorum to established infection model, collected duodenal tissue after infection within24h (0h,3h,6h,12h and24h), using real-time quantitative PCR to detect AvBD genes expression patterns during infection,the results showed that Salmonella pullorum infection within24h, AvBD1,3, and12did not detect the change of expression levels significantly; the expression levels of AvBD8,10,11,13and14was significantly (P <0.05) decrease at different time; the expression levels of AvBD2,4,5,6,7and9increased significantly at different time periods (P<0.05), in which the expression levels of AvBD6rised with largest rate, and24h after infection with the highest expression, so select AvBD6as the advantage chicken β-defensinof anti-Salmonella pullorum.2Structure-activity analysis of antimicrobial quality of AvBD6AvBD6physicochemical characterization shows that it has the general nature of antimicrobial peptides-cationic and amphiphilic; transmembrane prediction analysis shows AvBD6can not form a film channel and the target of AvBD6is likely to the bacterial cytoplasm; secondary structure analysis and spatial model building showed AvBD6has no a helix and amphiphilic domain, indicating that cell membrane action ability of AvBD6is relatively poor. Gel retardation assay fully explain AvBD6can act on the bacterial DNA and RNA.3Molecular design of AvBD6The molecular design was done on the basis of AvBD6spatial structure in order to strengthen the membrane action ability, reduce the isoelectric point and enhance the biological activity selectivity. After the neutral amino acid in AvBD6PSS loci was replaced with aspartate and alpha helix of the BF2antibacterial peptide derivatives was increased at the C end, the design of AvBD6-BF2peptide with three β folding fragments and an alpha helix structure was gained.The above results showed that AvBD6was the advantage chicken β-defensin of resisting against Salmonella pullorum infection and it had the ability of binding with DNA and RNA. Well-designed AvBD6-BF2peptide was obtained which would improve the sterilization specificity of AvBD6. Theoretical basis and new strategies for AvBD6substituting antibiotics in effective treatment of Salmonella pullorum infection were provided.