Biology Centre, Institute of Parasitology, Czech Academy of Sciences, Ceske Budejovice, Czechia.
Faculty of Science, University of South Bohemia, Ceske Budejovice, Czechia.
Front Cell Infect Microbiol. 2017 Dec 8;7:509. doi: 10.3389/fcimb.2017.00509. eCollection 2017.
Ticks are important vectors of serious human and animal disease-causing organisms, but their innate immunity can fight invading pathogens and may have the ability to reduce or block transmission to mammalian hosts. Lectins, sugar-binding proteins, can distinguish between self and non-self-oligosaccharide motifs on pathogen surfaces. Although tick hemolymph possesses strong lectin activity, and several lectins have already been isolated and characterized, little is known about the implementation of these molecules in tick immunity. Here, we have described and functionally characterized fibrinogen-related protein (FReP) lectins in Ixodes ticks. We have shown that the FReP family contains at least 27 genes () that could, based on phylogenetic and expression analyses, be divided into three groups with differing degrees of expansion. By using RNA interference-mediated gene silencing (RNAi) we demonstrated that IXO-A was the main lectin in tick hemolymph. Further, we found that ixoderins were important for phagocytosis of Gram-negative bacteria and yeasts by tick hemocytes and that their expression was upregulated upon injection of microbes, wounding, or after blood feeding. However, although the tick hemocytes could swiftly phagocytose spirochetes, their transmission and burst of infection in mice was not altered. Our results demonstrate that tick ixoderins are crucial immune proteins that work as opsonins in the tick hemolymph, targeting microbes for phagocytosis or lysis.
蜱是重要的人类和动物病原体载体，但它们先天免疫可以抵御入侵的病原体，并有能力减少或阻断向哺乳动物宿主的传播。凝集素是一种结合糖的蛋白质，能够区分病原体表面的自身和非自身寡糖基序。尽管蜱血淋巴具有很强的凝集素活性，并且已经分离和鉴定了几种凝集素，但对于这些分子在蜱免疫中的作用知之甚少。在这里，我们描述并功能表征了硬蜱中的纤维蛋白原相关蛋白 (FReP) 凝集素。我们表明，FReP 家族至少包含 27 个基因 ()，根据系统发育和表达分析，可以分为三组，具有不同程度的扩张。通过使用 RNA 干扰介导的基因沉默 (RNAi)，我们证明了 IXO-A 是蜱血淋巴中的主要凝集素。此外，我们发现 ixoderins 对于蜱血细胞吞噬革兰氏阴性细菌和酵母至关重要，并且它们的表达在注射微生物、创伤或吸血后上调。然而，尽管蜱血细胞能够迅速吞噬螺旋体，但它们在小鼠中的传播和感染爆发并没有改变。我们的结果表明，蜱 ixoderins 是重要的免疫蛋白，作为蜱血淋巴中的调理素，针对微生物进行吞噬或溶解。
