Identification of three novel avian beta-defensins from goose and their significance in the pathogenesis of Salmonella.

Here, we report the characterization of three avian β-defensins (AvBDs) from the goose, named anser_AvBD1, AvBD3, and AvBD6, respectively. All of anser_AvBDs exhibited broad antibacterial activity. In addition, the antibacterial activity of all of the AvBDs against Staphylococcus aureus and Proteus mirabilis decreased significantly in the presence of 100mM NaCl (P<0.01). None of the AvBDs showed hemolytic activity. In order to assess the significance of these anser_AvBDs in the infection of Salmonella enteritidis, mRNA expression of Toll-like receptor (TLR) 4 and anser_AvBDs in tissues of both control and infected geese was evaluated. We observed a significant up-regulation of TLR4, anser_AvBD1, 3, and 6 in some immune tissues evaluated, in response to S. enteritidis infection. These data demonstrated that TLR4 may serve a possible role in eliciting host immune responses to pathogens, and β-defensins may play a pivotal role in the host defense mechanisms of the goose.