Duck β-defensin 10 inhibits Salmonella enterica by disrupting bacterial membrane integrity and its association with gut microbiota dynamics

Salmonella infections pose a significant threat to waterfowl. Avian β-defensin 10 (AvBD10), a key molecule of host innate immunity, exhibits broad-spectrum antibacterial activity and immune regulatory function. However, research on the tissue-specific expression and antibacterial activity against Salmonella of AvBD10 in waterfowl remains limited. In this study, we first revealed the expression characteristics of AvBD10 in the tissues of ducks at different ages using in vivo experiments. Subsequently, we elucidated the interaction between AvBD10 and intestinal microorganisms, such as Salmonella, by combining 16S rDNA sequencing analysis of the microbiota in the cecum. Finally, we verified the antibacterial effect of AvBD10 on Salmonella using in vitro experiments. The results revealed that the expression of AvBD10 displayed notable (P<0.05) tissue-specific patterns, exhibiting variations associated with the developmental stage in ducks. In particular, AvBD10 was prominently expressed in the cecum during the initial brooding phase, with consistent modulation observed throughout maturation. In addition, AvBD10 expression shows a significant negative correlation (R=-0.460; 95% confidence intervals: -0.632 to -0.248; P<0.05) with the relative abundance of Salmonella in the cecum. Furthermore, AvBD10 exhibited a minimum inhibitory concentration of 62.5 μg/mL against Salmonella enterica and exerted its antibacterial properties by electrostatically binding to the Salmonella cell membrane via positively charged amino acid residues, leading to disruption of the membrane structure. This study provides a significant theoretical foundation for the green and healthy breeding of livestock and poultry.