Xie Haiwei, Wei Jingguang, Qin Qiwei
Department of Food and Bioengineering, Bengbu College, Bengbu, 233030, PR China.
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, PR China.
Fish Shellfish Immunol. 2016 Nov;58:96-102. doi: 10.1016/j.fsi.2016.09.015. Epub 2016 Sep 12.
Antimicrobial peptides (AMPs) are ubiquitously found in living organisms and are an important component in innate immune response. Tachyplesin I is a potent antimicrobial peptide isolated from the hemocytes of the horseshoe crab, Tachypleus tridentatus. Previous studies have shown that the 17-residue peptide exhibits a wide spectrum of antimicrobial activity against Gram-negative and Gram-positive bacteria, fungi, protozoa, and viruses. However, the efficiencies and defense mechanisms of the Tachyplesin I against fish viruses are still unknown. In this study, Tachyplesin I showed a key role in inhibiting the infection and replication of two kinds of newly emerging marine fish viruses, an enveloped DNA virus of Singapore grouper iridovirus (SGIV), and a non-enveloped RNA virus of viral nervous necrosis virus (RGNNV). Synthetic peptides of Tachyplesin I incubated with virus or cells before infection reduced the viral infectivity. Synthetic peptides of Tachyplesin I drastically decreased SGIV and RGNNV titers and viral gene expression. Grouper spleen (GS) and brain (GB) cells over-expressing Tachyplesin I (GS/pcDNA3.1-flag-Tac I and GB/pcDNA3.1-flag-Tac I) support the inhibition of viral infection. Tachyplesin I activated type I IFN and Interferon-sensitive response element (ISRE) in vitro. The promoter activity of IFN-β and ISRE were significantly up-regulated in cells transfected with pcDNA3.1-flag-Tac I after infection with SGIV and VNNV. These results suggest that Tachyplesin I is importantly involved in host immune responses to invasion of viral pathogens.
抗菌肽（AMPs）广泛存在于生物体内，是先天免疫反应的重要组成部分。鲎素I是一种从中国鲎血细胞中分离得到的强效抗菌肽。先前的研究表明，这种由17个氨基酸残基组成的肽对革兰氏阴性菌、革兰氏阳性菌、真菌、原生动物和病毒具有广泛的抗菌活性。然而，鲎素I对鱼类病毒的作用效率和防御机制仍不清楚。在本研究中，鲎素I在抑制两种新出现的海洋鱼类病毒的感染和复制中发挥了关键作用，这两种病毒分别是新加坡石斑鱼虹彩病毒（SGIV），一种有包膜的DNA病毒，以及病毒性神经坏死病毒（RGNNV），一种无包膜的RNA病毒。在感染前将鲎素I的合成肽与病毒或细胞一起孵育可降低病毒感染性。鲎素I的合成肽显著降低了SGIV和RGNNV的滴度以及病毒基因表达。过表达鲎素I的石斑鱼脾脏（GS）和脑（GB）细胞（GS/pcDNA3.1-flag-Tac I和GB/pcDNA3.1-flag-Tac I）支持对病毒感染的抑制。鲎素I在体外激活了I型干扰素和干扰素敏感反应元件（ISRE）。在用SGIV和VNNV感染后，转染了pcDNA3.1-flag-Tac I的细胞中IFN-β和ISRE的启动子活性显著上调。这些结果表明，鲎素I在宿主对病毒病原体入侵的免疫反应中起着重要作用。
