Lectins are non-immunological carbohydrate-binding proteins classified on the basis of their structure, origin, and sugar specificity. The binding specificity of such proteins with the surface glycan moiety determines their activity and clinical applications. Thus, lectins hold great potential as diagnostic and drug discovery agents and as novel biopharmaceutical products. In recent years, significant advancements have been made in understanding plant and microbial lectins as therapeutic agents against various viral diseases. Among them, mannose-specific lectins have being proven as promising antiviral agents against a variety of viruses, such as HIV, Influenza, Herpes, Ebola, Hepatitis, Severe Acute Respiratory Syndrome Coronavirus-1 (SARS-CoV-1), Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) and most recent Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The binding of mannose-binding lectins (MBLs) from plants and microbes to high-mannose containing N-glycans (which may be simple or complex) of glycoproteins found on the surface of viruses has been found to be highly specific and mainly responsible for their antiviral activity. MBLs target various steps in the viral life cycle, including viral attachment, entry and replication. The present review discusses the brief classification and structure of lectins along with antiviral activity of various mannose-specific lectins from plants and microbial sources and their diagnostic and therapeutic applications against viral diseases.

Graphical abstract

中文翻译：

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甘露糖特异性植物和微生物凝集素作为抗病毒剂：综述

凝集素是非免疫性碳水化合物结合蛋白，根据其结构、起源和糖特异性进行分类。此类蛋白质与表面聚糖部分的结合特异性决定了它们的活性和临床应用。因此，凝集素作为诊断和药物发现剂以及新型生物制药产品具有巨大的潜力。近年来，人们在了解植物和微生物凝集素作为各种病毒性疾病的治疗剂方面取得了重大进展。其中，甘露糖特异性凝集素已被证明是针对多种病毒的有前景的抗病毒药物，如艾滋病毒、流感、疱疹、埃博拉、肝炎、严重急性呼吸系统综合症冠状病毒-1（SARS-CoV-1）、中东呼吸道疾病冠状病毒综合症 (MERS-CoV) 和最近的严重急性呼吸系统综合症冠状病毒-2 (SARS-CoV-2)。植物和微生物中的甘露糖结合凝集素 (MBL) 与病毒表面糖蛋白的高甘露糖 N-聚糖（可能是简单的或复杂的）的结合被发现具有高度特异性，这主要是其抗病毒活性。MBL 针对病毒生命周期中的各个步骤，包括病毒附着、进入和复制。本综述讨论了凝集素的简要分类和结构，以及来自植物和微生物来源的各种甘露糖特异性凝集素的抗病毒活性及其针对病毒性疾病的诊断和治疗应用。

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