Both α2,3- and α2,6-linked sialic acids on O-linked glycoproteins act as functional receptors for porcine Sapovirus.
Both α2,3- and α2,6-linked sialic acids on O-linked glycoproteins act as functional receptors for porcine Sapovirus.
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O连接糖蛋白上的α2,3-和α2,6-连接的唾液酸都作为猪Sapovirus的功能受体。
DOI：
10.1371/journal.ppat.1004172
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发表时间：
2014-06
期刊：
影响因子：
6.7
通讯作者：
Cho KO
中科院分区：
文献类型：
--
作者：
Kim DS;Hosmillo M;Alfajaro MM;Kim JY;Park JG;Son KY;Ryu EH;Sorgeloos F;Kwon HJ;Park SJ;Lee WS;Cho D;Kwon J;Choi JS;Kang MI;Goodfellow I;Cho KO
沙波病毒属杯状病毒科，是引起人和猪急性胃肠炎的重要病原。目前，猪痘病毒（PSaV）科登株仍然是唯一可培养的成员的痘病毒属。虽然已知一些杯状病毒利用碳水化合物受体进入和感染，但沙波病毒的功能性受体尚不清楚。为了表征PSaV的Cowden株的功能性受体，我们在模拟和PSaV感染的细胞培养物和/或仔猪肠组织切片中进行了一系列全面的蛋白质-配体生化测定。PSaV既不显示与来自任何物种的红细胞的血凝活性，也不显示与合成的组织血型抗原的结合活性，表明PSaV不使用组织血型抗原作为受体。唾液酸和霍乱弧菌神经氨酸酶（NA）可明显阻断PSaV的粘附和感染，提示α 2，3-连接、α 2，6-连接或α 2，8-连接的唾液酸在病毒粘附中起作用。然而，用唾液酸酶S（SS）或怀槐凝集素（MAL）（均对α 2，3-连接唾液酸具有特异性）或黑接骨木凝集素（SNL）（对α 2，6-连接唾液酸具有特异性）处理细胞仅部分抑制病毒附着和感染。这些结果表明，PSaV识别α 2，3-和α 2，6-连接的唾液酸用于病毒附着和感染。用蛋白酶或苄基4-O-β-D-吡喃半乳糖基-β-D-吡喃葡萄糖苷（苄基GalNAc）处理细胞，可抑制O-连接的糖基化，也可减少病毒结合和感染，而抑制糖脂合成或N-连接的糖基化对病毒结合或感染没有这种影响。这些数据表明PSaV与细胞受体结合，这些受体由通过O-连接糖基化连接的糖蛋白上的α 2，3-和α 2，6-连接唾液酸组成。虽然肠道致病性沙波病毒和诺如病毒是人类和动物急性胃肠炎的主要原因，但由于缺乏完全允许的细胞培养系统，这些普遍存在的病原体的病毒发病机制和免疫的研究受到阻碍。猪痘病毒Cowden株提供了一个合适的系统，可用于确定病毒致病的分子机制。先前的研究表明，碳水化合物和糖脂在杯状病毒科成员的附着中起重要作用;组织血型抗原（HBGAs）被诺如病毒基因组I至IV以及Lagovirus和Ekovirus属的成员使用，而末端唾液酸被认为是猫杯状病毒和鼠诺如病毒的受体。然而，迄今为止，碳水化合物在sapoviruses的生活周期中的作用仍然是未知的。我们发现猪痘病毒通过α 2，3-和α 2，6-连接的末端唾液酸与O-连接的糖蛋白结合。这些努力，发现和见解将大大有助于更好地了解sapovirus的生命周期。
Sapovirus, a member of the Caliciviridae family, is an important cause of acute gastroenteritis in humans and pigs. Currently, the porcine sapovirus (PSaV) Cowden strain remains the only cultivable member of the Sapovirus genus. While some caliciviruses are known to utilize carbohydrate receptors for entry and infection, a functional receptor for sapovirus is unknown. To characterize the functional receptor of the Cowden strain of PSaV, we undertook a comprehensive series of protein-ligand biochemical assays in mock and PSaV-infected cell culture and/or piglet intestinal tissue sections. PSaV revealed neither hemagglutination activity with red blood cells from any species nor binding activity to synthetic histo-blood group antigens, indicating that PSaV does not use histo-blood group antigens as receptors. Attachment and infection of PSaV were markedly blocked by sialic acid and Vibrio cholerae neuraminidase (NA), suggesting a role for α2,3-linked, α2,6-linked or α2,8-linked sialic acid in virus attachment. However, viral attachment and infection were only partially inhibited by treatment of cells with sialidase S (SS) or Maackia amurensis lectin (MAL), both specific for α2,3-linked sialic acid, or Sambucus nigra lectin (SNL), specific for α2,6-linked sialic acid. These results indicated that PSaV recognizes both α2,3- and α2,6-linked sialic acids for viral attachment and infection. Treatment of cells with proteases or with benzyl 4-O-β-D-galactopyranosyl-β-D-glucopyranoside (benzylGalNAc), which inhibits O-linked glycosylation, also reduced virus binding and infection, whereas inhibition of glycolipd synthesis or N-linked glycosylation had no such effect on virus binding or infection. These data suggest PSaV binds to cellular receptors that consist of α2,3- and α2,6-linked sialic acids on glycoproteins attached via O-linked glycosylation. Although enteropathogenic sapoviruses and noroviruses are leading causes of acute gastroenteritis in both humans and animals, the study of viral pathogenesis and immunity of these ubiquitous pathogens has been hampered due to the lack of a fully permissive cell culture system. Porcine sapovirus Cowden strain provides a suitable system that can be used to identify the molecular mechanisms of viral pathogenesis. Previous studies have shown that carbohydrates and glycolipids play important roles in the attachment of members of the Caliciviridae; histo-blood group antigens (HBGAs) are used by Norovirus genogroups I to IV, as well as members of the Lagovirus, and Recovirus genera, whereas terminal sialic acid is recognized as a receptor for feline calicivirus and murine norovirus. To date, however, the role of carbohydrates in the life cycle of sapoviruses has remained largely unknown. We found that porcine sapovirus binds to susceptible host cells through both α2,3- and α2,6-linked terminal sialic acids which are attached to O-linked glycoproteins. These efforts, findings and insights will significantly contribute to a better understanding of the sapovirus life cycle.
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