Efficient N-glycosylation at position 37, but not at position 146, in the street rabies virus glycoprotein reduces pathogenicity
Efficient N-glycosylation at position 37, but not at position 146, in the street rabies virus glycoprotein reduces pathogenicity
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DOI：
10.1016/j.virusres.2013.10.015
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发表时间：
2014-01-22
期刊：
影响因子：
5
通讯作者：
Nishizono, Akira
中科院分区：
文献类型：
--
作者：
Yamada, Kentaro;Noguchi, Kazuko;Nishizono, Akira
大多数街头狂犬病病毒在其糖蛋白（G蛋白）中具有两个N-糖基化位点，即，在Asn（37）和Asn（319）处，但Asn（37）通常不会以有效的方式进行核心糖基化。在此之前，我们报道了在Asn（194）或Asn（247）处的单个额外的N-糖基化在狂犬病病毒的细胞适应性和降低致病性中的可能作用，这表明N-糖基化与狂犬病病毒的进化密切相关。在这项研究中，我们的特点是两个新的N-糖基化修饰的变体，N5C#7和N5C#8，这是使用有限稀释法克隆后，连续传代的街头狂犬病病毒株1088小鼠神经母细胞瘤衍生的NA细胞。N5C#7在G蛋白中具有L38 R突变，这导致Asn处的有效核心糖基化（37）。另一方面，N5C#8在G蛋白中具有D146 N突变，这导致在位置146处的额外N-糖基化。与亲本菌株相比，这两种变体在NA细胞中高效复制。与亲本菌株一样，这两种变体在脑内接种后引起成年小鼠的致命感染。然而，N5C#7在肌内接种后表现出降低的致病性，而N5C#8表现出与亲本菌株相同的致病性水平。总之，在位置37处的有效核心糖基化与细胞适应和街头狂犬病病毒的致病性降低有关。相比之下，尽管与细胞适应有关，但在位置146处的额外N-糖基化不影响致病性，这与已经从狂犬病动物中分离出在位置37、146和319处具有N-糖基化位点的街头狂犬病病毒株的报道一致。因此，本研究的结果提供了额外的证据，支持G蛋白N-糖基化和狂犬病毒进化之间的关系。(C)2013爱思唯尔有限公司版权所有。
Most street rabies viruses have two N-glycosylation sites in their glycoproteins (G proteins), i.e., at Asn(37) and Asn(319), but Asn(37) is usually not core-glycosylated in an efficient manner. Previously, we reported the possible roles of single additional N-glycosylations at Asn(194) or Asn(247) in the cell adaptation and reduced pathogenicity of a street rabies virus, which suggest that N-glycosylation is closely related to the evolution of rabies viruses. In this study, we characterized two novel N-glycosylation-modified variants, N5C#7 and N5C#8, which were cloned using the limiting dilution method after serial passaging of the street rabies virus strain 1088 in mouse neuroblastoma-derived NA cells. N5C#7 had an L38R mutation in the G protein, which led to efficient core glycosylation at Asn(37). On the other hand, N5C#8 had a D146N mutation in the G protein, which led to an additional N-glycosylation at position 146. Both variants replicated highly efficiently in NA cells compared with the parental strain. Like the parental strain, both variants caused lethal infections in adult mice after intracerebral inoculation. However, N5C#7 exhibited reduced pathogenicity after intramuscular inoculation, whereas N5C#8 displayed the same level of pathogenicity as the parental strain. In summary, the efficient core glycosylation at position 37 was related to cell adaptation and the reduced pathogenicity of the street rabies virus. By contrast, despite of being related to cell adaptation, the additional N-glycosylation at position 146 did not affect the pathogenicity, which is consistent with a report that street rabies virus strains with N-glycosylation sites at positions 37, 146, and 319 have been isolated from rabid animals. Thus, the results of the present study provide additional evidence that supports the relationship between G protein N-glycosylation and rabies virus evolution. (C) 2013 Elsevier B.V. All rights reserved.