Institutes of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, People's Republic of China.
Department of Clinical Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, People's Republic of China.
Parasit Vectors. 2017 Oct 2;10(1):455. doi: 10.1186/s13071-017-2397-9.
Ticks are second to mosquitoes as vectors of human arthropod-borne diseases. Ticks rely heavily on antimicrobial peptides (AMPs) to defend against microbes and defensins are major components of innate immunity in ticks.
Two novel defensin genes, named HlDFS1 and HlDFS2, were identified from a cDNA library of the hard tick Haemaphysalis longicornis collected in southeast China. The peptides encoded by both genes shares typical features of type-2 arthropod defensin superfamily. The expressions of both genes increased in ticks during blood-feeding. The synthetic minimum functional peptides HlDFS1 and HlDFS2 showed broad spectrum antimicrobial activity against various Gram-positive and Gram-negative bacteria. Moreover, HlDFS1 and HlDFS2 exhibit bactericidal activity to some drug resistant bacteria. HlDFS1, but not HlDFS2, showed inhibitory activity against fungus Candida albicans. HlDFS1 and HlDFS2 had no significant hemolysis effect on human erythrocytes at low concentrations and did not impair mammalian cell survival. Finally, HlDFS1 and HlDFS2 significantly protected mice against lethal infection by Staphylococcus aureus and Micrococcus luteus.
HlDFS1 and HlDFS2 are two novel functional defensins from the hard tick Haemaphysalis longicornis. They showed bactericidal activity against various Gram-positive and Gram-negative bacteria and significantly protect mice against lethal bacterial infection. Thus, HlDFS1 and HlDFS2 can be introduced to the medical field as new drug candidates with antibacterial activity.
蜱虫在人类节肢动物病媒中仅次于蚊子。蜱虫严重依赖抗菌肽（AMPs）来抵御微生物，防御素是蜱虫固有免疫的主要成分。
从中国东南地区采集的硬蜱长角血蜱 cDNA 文库中鉴定出两种新型防御素基因，命名为 HlDFS1 和 HlDFS2。这两种基因编码的肽都具有典型的 2 型节肢动物防御素超家族特征。这两种基因在蜱虫吸血过程中的表达均增加。合成的最小功能肽 HlDFS1 和 HlDFS2 对各种革兰氏阳性和革兰氏阴性菌均具有广谱抗菌活性。此外，HlDFS1 和 HlDFS2 对一些耐药菌具有杀菌活性。HlDFS1 而非 HlDFS2 对真菌白色念珠菌具有抑制活性。HlDFS1 和 HlDFS2 在低浓度时对人红细胞无明显溶血作用，不影响哺乳动物细胞的存活。最后，HlDFS1 和 HlDFS2 显著保护小鼠免受金黄色葡萄球菌和藤黄微球菌的致死性感染。
HlDFS1 和 HlDFS2 是来自硬蜱长角血蜱的两种新型功能性防御素。它们对各种革兰氏阳性和革兰氏阴性菌具有杀菌活性，并显著保护小鼠免受致命的细菌感染。因此，HlDFS1 和 HlDFS2 可以作为具有抗菌活性的新型药物候选物引入医学领域。
