Influenza A penetrates host mucus by cleaving sialic acids with neuraminidase.
Influenza A penetrates host mucus by cleaving sialic acids with neuraminidase.
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DOI：
10.1186/1743-422x-10-321
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发表时间：
2013-11-22
期刊：
影响因子：
4.8
通讯作者：
Gagneux P
中科院分区：
文献类型：
--
作者：
Cohen M;Zhang XQ;Senaati HP;Chen HW;Varki NM;Schooley RT;Gagneux P
甲型流感病毒（IAV）神经氨酸酶（NA）从聚糖切割唾液酸（Sias）。用奥司他韦抑制NA抑制病毒感染和从培养的人气道上皮细胞释放病毒。NA在病毒退出中的作用已被充分确立：它通过从感染细胞和子代病毒体上的糖缀合物切割Sias来释放出芽的病毒体。NA在病毒进入中的作用尚不清楚。宿主呼吸道上皮细胞分泌富含大量唾液酸化糖蛋白的粘液层;这些糖蛋白可以通过模拟细胞表面的唾液酸化受体来抑制病毒进入。有人认为NA通过切割这些唾液酸化诱饵使流感病毒穿透粘液，但确切的机制尚未建立。我们使用冷冻的人气管/支气管组织切片、珠结合的纯化的人唾液粘蛋白（HSM）和纯化的猪颌下粘蛋白（PSM）测试了IAV与分泌粘液的相互作用。使用用具有已知Sia含量的纯化的HSM和PSM包被的MDCK细胞分析粘液的保护作用。奥司他韦用于抑制NA活性，荧光报告底物4 MU-Neu 5Ac用于定量NA活性。IAV以Sia依赖性方式与冷冻人气管/支气管组织的分泌粘液层结合。HSM抑制IAV感染是Sia剂量依赖性的，但PSM不能抑制下层细胞的感染。HSM竞争性抑制报告底物4 MU-Neu 5Ac的NA切割。人IAV有效地从HSM而不是从PSM切割Sias，并且结合到HSM而不是PSM。IAV与冷冻组织切片和粘液包被珠上的人类粘液相互作用。唾液酸化的人粘液对IAV感染的抑制是剂量依赖性的，并且当用奥司他韦抑制NA时增强。因此，NA在感染的初始阶段切割唾液酸化诱饵。了解IAV与宿主粘蛋白的相互作用是药物开发的一个有前途的新途径。
Influenza A virus (IAV) neuraminidase (NA) cleaves sialic acids (Sias) from glycans. Inhibiting NA with oseltamivir suppresses both viral infection, and viral release from cultured human airway epithelial cells. The role of NA in viral exit is well established: it releases budding virions by cleaving Sias from glycoconjugates on infected cells and progeny virions. The role of NA in viral entry remains unclear. Host respiratory epithelia secrete a mucus layer rich in heavily sialylated glycoproteins; these could inhibit viral entry by mimicking sialylated receptors on the cell surface. It has been suggested that NA allows influenza to penetrate the mucus by cleaving these sialylated decoys, but the exact mechanism is not yet established. We tested IAV interaction with secreted mucus using frozen human trachea/bronchus tissue sections, and bead-bound purified human salivary mucins (HSM) and purified porcine submaxillary mucins (PSM). The protective effect of mucus was analyzed using MDCK cells coated with purified HSM and PSM with known Sia content. Oseltamivir was used to inhibit NA activity, and the fluorescent reporter substrate, 4MU-Neu5Ac, was used to quantify NA activity. IAV binds to the secreted mucus layer of frozen human trachea/bronchus tissues in a Sia dependent manner. HSM inhibition of IAV infection is Sia dose-dependent, but PSM cannot inhibit infection of underlying cells. HSM competitively inhibits NA cleavage of 4MU-Neu5Ac, reporter substrate. Human IAV effectively cleaves Sias from HSM but not from PSM, and binds to HSM but not to PSM. IAV interacts with human mucus on frozen tissue sections and mucus-coated beads. Inhibition of IAV infection by sialylated human mucus is dose-dependent, and enhanced when NA is inhibited with oseltamivir. Thus NA cleaves sialylated decoys during initial stages of infection. Understanding IAV interactions with host mucins is a promising new avenue for drug development.