Amino Acid Variation at VP1-145 of Enterovirus 71 Determines Attachment Receptor Usage and Neurovirulence in Human Scavenger Receptor B2 Transgenic Mice
Amino Acid Variation at VP1-145 of Enterovirus 71 Determines Attachment Receptor Usage and Neurovirulence in Human Scavenger Receptor B2 Transgenic Mice
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DOI：
10.1128/jvi.00681-18
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发表时间：
2018-08-01
影响因子：
5.4
通讯作者：
Koike, Satoshi
中科院分区：
文献类型：
--
作者：
Kobayashi, Kyousuke;Sudaka, Yui;Koike, Satoshi
肠道病毒71（EV 71）的感染受细胞表面受体的影响，包括病毒脱壳所需的人清道夫受体B2（hSCARB 2）和附着受体，如硫酸乙酰肝素（HS），其结合病毒但不支持脱壳。衣壳蛋白VP 1的氨基酸残基145影响病毒与HS的结合和小鼠中的毒力。然而，这种氨基酸对人类致病性的贡献尚不清楚。我们产生在位置145处具有甘氨酸（VP 1 - 145 G）或谷氨酸（VP 1 - 145 E）的EV 71。VP 1 - 145 G而非VP 1 - 145 E以HS依赖性方式增强细胞培养物中的病毒感染。然而，VP 1 - 145 G病毒在野生型乳鼠和表达hSCARB 2的转基因小鼠模型中显示减毒表型，而VP 1 - 145 E病毒在两种模型中均显示毒力表型。因此，HS结合特性和体内毒力呈负相关。免疫组化分析表明，HS是高表达的血管内皮细胞和一些其他类型的细胞hSCARB 2表达低或检测不到的水平。VP 1 - 145 G病毒在体外可与hSCARB 2转基因和非转基因小鼠的组织匀浆结合，静脉接种后病毒滴度立即降低。此外，VP 1 - 145 G病毒未能在小鼠器官中良好地传播。这些数据表明，VP 1 - 145 G病毒在体内循环过程中被附着受体如HS吸附，导致HS阳性细胞的感染失败。这种捕获效应被认为是VP 1 - 145 G病毒减毒的主要机制。重要性宿主细胞表面表达的附着受体被认为通过增加遇到真实受体的机会来增强EV 71感染。虽然这已被证实使用细胞培养的一些病毒，在体内的重要性的附着受体是未知的。这份报告为这个问题提供了一个意想不到的答案。我们证明了VP 1 - 145 G病毒与HS结合，并在hSCARB 2依赖性动物感染模型中显示减毒表型。HS在以低水平或不可检测水平表达hSCARB 2的细胞中高度表达。我们的数据表明，HS结合指导VP 1 - 145 G病毒走向流产感染，并保持病毒远离hSCARB 2阳性细胞。因此，尽管VP 1 - 145 G病毒利用HS的能力在某些培养细胞中的复制中可能是一个优势，但它在体内复制中成为一个严重的缺点。这种吸附被认为是与附着受体使用相关的衰减的主要机制。
Infection by enterovirus 71 (EV71) is affected by cell surface receptors, including the human scavenger receptor B2 (hSCARB2), which are required for viral uncoating, and attachment receptors, such are heparan sulfate (HS), which bind virus but do not support uncoating. Amino acid residue 145 of the capsid protein VP1 affects viral binding to HS and virulence in mice. However, the contribution of this amino acid to pathogenicity in humans is not known. We produced EV71 having glycine (VP1-145G) or glutamic acid (VP1-145E) at position 145. VP1-145G, but not VP1-145E, enhanced viral infection in cell culture in an HS-dependent manner. However, VP1-145G virus showed an attenuated phenotype in wild-type suckling mice and in a transgenic mouse model expressing hSCARB2, while VP1-145E virus showed a virulent phenotype in both models. Thus, the HS-binding property and in vivo virulence are negatively correlated. Immunohistochemical analyses showed that HS is highly expressed in vascular endothelial cells and some other cell types where hSCARB2 is expressed at low or undetectable levels. VP1-145G virus bound to tissue homogenate of both hSCARB2 transgenic and nontransgemc mice in vitro, and the viral titer was reduced in the bloodstream immediately after intravenous inoculation. Furthermore, VP1-145G virus failed to disseminate well in the mouse organs. These data suggest that VP1-145G virus is adsorbed by attachment receptors such as HS during circulation in vivo, leading to abortive infection of HS-positive cells. This trapping effect is thought to be a major mechanism of attenuation of the VP1-145G virus.IMPORTANCE Attachment receptors expressed on the host cell surface are thought to enhance EV71 infection by increasing the chance of encountering true receptors. Although this has been confirmed using cell culture for some viruses, the importance of attachment receptors in vivo is unknown. This report provides an unexpected answer to this question. We demonstrated that the VP1-145G virus binds to HS and shows an attenuated phenotype in an hSCARB2-dependent animal infection model. HS is highly expressed in cells that express hSCARB2 at low or undetectable levels. Our data indicate that HS binding directs VP1-145G virus toward abortive infection and keeps virus away from hSCARB2-positive cells. Thus, although the ability of VP1-145G virus to use HS might be an advantage in replication in certain cultured cells, it becomes a serious disadvantage in replication in vivo. This adsorption is thought to be a major mechanism of attenuation associated with attachment receptor usage.