Galectins are well-known β-galactoside-binding proteins, which play vital roles in innate immune responses of both vertebrates and invertebrates. However, knowledge regarding invertebrate galectins is still in its infancy. With the intention of filling the knowledge gap, here we identified a quadruple domain-containing galectin from marine invertebrate disk abalone, Haliotis discus discus (AbGalec), and characterized it. AbGalec consisted of four distinct carbohydrate-recognition domains (CRDs) and lacked a signal peptide. Expression analysis revealed AbGalec to be ubiquitously expressed in all the examined early embryonic stages of abalone, with highest expression in the 16-cell stage, suggesting the importance of AbGalec in early developmental processes. Tissue distribution analysis revealed the highest expression of AbGalec in abalone mantle, followed by that in gills and hemocytes. Immune challenge experiments revealed significant upregulation of AbGalec at 24 h and 48 h post injection (p.i.) with bacterial and viral components. These results suggested the possible involvement of AbGalec in host defense mechanisms. Polyinosinic: polycytidylic acid (Poly I:C) and viral hemorrhagic septicemia virus (VHSV) injections were capable of inducing AbGalec transcript expression more prominently than bacterial stimulants, thus providing evidence for its role in viral infections. We determined the virus-neutralizing ability of a quadruple domain-containing galectin for the first time, by analyzing the downregulation of VHSV transcripts during the overexpression of AbGalec. Significant downregulation of VHSV transcripts was observed after 24 h and 48 h of post infection. Collectively, our findings reveal the potent antiviral responses of molluscan quadruple domain-containing galectin, AbGalec, along with its involvement in innate immunity.

半乳凝素是众所周知的β-半乳糖苷结合蛋白，在脊椎动物和无脊椎动物的先天免疫应答中起着至关重要的作用。但是，有关无脊椎动物半乳凝素的知识仍处于起步阶段。与填充知识间隙的意向，在这里我们确定从海洋无脊椎动物磁盘鲍鱼，四重结构域的半乳凝素鲍铁饼（AbGalec），和其特征在于它。AbGalec由四个不同的碳水化合物识别域（CRD）组成，并且缺少信号肽。表达分析显示AbGalec在所有检查过的鲍鱼早期胚胎阶段都普遍表达，在16细胞阶段表达最高，这表明AbGalec在早期发育过程中的重要性。组织分布分析显示，AbGalec在鲍鱼套中表达最高，其次是在and和血细胞中。免疫激发实验显示，在注射后（pi）的24小时和48小时，细菌和病毒成分显着上调了AbGalec。这些结果表明AbGalec可能参与了宿主防御机制。聚肌苷酸：聚胞苷酸（Poly I：C）和病毒性出血性败血病病毒（VHSV）注射液均能诱导AbGalec转录表达比细菌刺激剂更显着，因此提供了其在病毒感染中的作用的证据。我们通过分析AbGalec过表达过程中VHSV转录物的下调，首次确定了含四个域的半乳凝素的病毒中和能力。感染后24小时和48小时后观察到VHSV转录物的显着下调。总的来说，我们的发现揭示了含软体动物四联结构域的半乳凝集素AbGalec的有效抗病毒反应，以及其参与先天免疫的能力。