Antimicrobial peptides (AMPs) are an important element of the innate immune system of all living organisms and serve as a barrier that safeguards the organisms against a wide range of pathogens. Fishes are proven to be a prospective source of AMPs, and β-defensins form an important family of AMPs with potent antimicrobial, chemotactic and immunomodulatory activities. The present study reports a β-defensin AMP sequence (Lc-BD) from the Asian sea bass, Lates calcarifer, a commercially important fish species in tropical and subtropical regions of Asia and the Pacific. A 202-bp cDNA fragment with an open reading frame encoding 63 amino acids (aa) was obtained from the mRNA of gill tissue by RT-PCR. The deduced aa sequence of Lc-BD possessed a signal and a mature peptide region with 20 and 43 aa residues, respectively. Lc-BD was characterized at the molecular level, and a molecular weight of 5.24 kDa and a net charge of +4.5 was predicted for the mature peptide. The molecular characterization of Lc-BD revealed the presence of three intramolecular disulphide bonds involving the six conserved cysteine residues in the sequence, and the phylogenetic analysis of Lc-BD showed a close relationship with β-defensins from fishes like Siniperca chuatsi, Argyrosomus regius, Trachinotus ovatus and Oplegnathus fasciatus.

抗菌肽 (AMP) 是所有生物体先天免疫系统的重要组成部分，是保护生物体免受多种病原体侵害的屏障。鱼类被证明是 AMP 的潜在来源，而 β-防御素形成了一个重要的 AMP 家族，具有强大的抗菌、趋化和免疫调节活性。本研究报告了来自亚洲鲈鱼Lates calcarifer的 β-防御素 AMP 序列 ( Lc -BD)，该鲈鱼是亚洲和太平洋热带和亚热带地区具有重要商业价值的鱼类。通过RT-PCR从鳃组织的mRNA中获得一个202-bp的cDNA片段，其开放阅读框编码63个氨基酸（aa）。推导出的Lc 的aa 序列-BD 具有信号区和成熟肽区，分别具有 20 和 43 个氨基酸残基。Lc -BD 在分子水平上进行了表征，预测成熟肽的分子量为 5.24 kDa，净电荷为 +4.5。Lc -BD的分子特征显示存在三个分子内二硫键，涉及序列中六个保守的半胱氨酸残基，并且Lc -BD的系统发育分析显示与来自Siniperca chuatsi、Argyrosomus regius、Argyrosomus regius、Trachinotus ovatus和Oplegnathus fasciatus。