Colleage of Animal Science and Technology, Northeast Agricultural University, Harbin, PR China.
PLoS One. 2012;7(10):e47743. doi: 10.1371/journal.pone.0047743. Epub 2012 Oct 24.
In the current study, five novel avian β-defensins (AvBDs) were identified and characterized in tissues from Peking ducks (Anas platyrhynchos). The nucleotide sequences of these cDNAs comprised 198 bp, 182 bp, 201 bp, 204 bp, and 168 bp, and encoded 65, 60, 66, 67, and 55 amino acids, respectively. Homology, characterization and comparison of these genes with AvBD from other avian species confirmed that they were Apl_AvBD1, 3, 5, 6, and 16. Recombinant AvBDs were produced and purified by expressing these genes in Escherichia coli. In addition, peptides were synthesized according to the respective AvBD sequences. Investigation of the antibacterial activity of the Apl_AvBDs showed that all of them exhibited antibacterial activity against all 12 bacteria investigated (P<0.05 or P<0.01). In addition, the antibacterial activity of all of the AvBDs against M. tetragenus and P. multocida decreased significantly in the presence of 150 mM NaCl (P<0.01). None of the AvBDs showed hemolytic activity. Consistent with their broad-spectrum antibacterial activity, the five novel Apl_AvBDs inhibited replication of duck hepatitis virus (DHV) in vitro significantly (P<0.05). The mRNA expression of all five Apl_AvBD in most tissues, including immune organs and the liver, was upregulated in response to DHV infection at different time points. These findings provide evidence that these defensins activate the immune response to combat microbial infection.
在本研究中，鉴定并描述了北京鸭（Anas platyrhynchos）组织中的五种新型禽β-防御素（AvBDs）。这些 cDNA 的核苷酸序列分别为 198bp、182bp、201bp、204bp 和 168bp，编码 65、60、66、67 和 55 个氨基酸。这些基因与其他禽类 AvBD 的同源性、特征和比较证实它们分别是 Apl_AvBD1、3、5、6 和 16。通过在大肠杆菌中表达这些基因来生产和纯化重组 AvBDs。此外，还根据各自的 AvBD 序列合成了肽。对 Apl_AvBDs 的抗菌活性进行研究表明，它们都对所有 12 种研究的细菌具有抗菌活性（P<0.05 或 P<0.01）。此外，在存在 150mM NaCl 的情况下，所有 AvBDs 对 M. tetragenus 和 P. multocida 的抗菌活性均显著降低（P<0.01）。没有 AvBD 显示溶血活性。与它们广谱的抗菌活性一致，这五种新型 Apl_AvBDs 显著抑制了鸭肝炎病毒（DHV）在体外的复制（P<0.05）。在不同的时间点，五种 Apl_AvBD 中的所有基因在包括免疫器官和肝脏在内的大多数组织中的 mRNA 表达都上调，以响应 DHV 感染。这些发现为这些防御素激活免疫反应以对抗微生物感染提供了证据。
