Strauss Mike, Schotte Lise, Thys Bert, Filman David J, Hogle James M
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.
Department of Pharmaceutical Biotechnology and Molecular Biology, Center for Neurosciences, Vrije Universiteit Brussel, Brussels, Belgium Department of Clinical Chemistry and Radio-immunology, Universitair Ziekenhuis Brussel, Brussels, Belgium.
J Virol. 2016 Jan 13;90(7):3496-505. doi: 10.1128/JVI.03017-15.
Nanobodies, or VHHs, that recognize poliovirus type 1 have previously been selected and characterized as candidates for antiviral agents or reagents for standardization of vaccine quality control. In this study, we present high-resolution cryo-electron microscopy reconstructions of poliovirus with five neutralizing VHHs. All VHHs bind the capsid in the canyon at sites that extensively overlap the poliovirus receptor-binding site. In contrast, the interaction involves a unique (and surprisingly extensive) surface for each of the five VHHs. Five regions of the capsid were found to participate in binding with all five VHHs. Four of these five regions are known to alter during the expansion of the capsid associated with viral entry. Interestingly, binding of one of the VHHs, PVSS21E, resulted in significant changes of the capsid structure and thus seems to trap the virus in an early stage of expansion.
We describe the cryo-electron microscopy structures of complexes of five neutralizing VHHs with the Mahoney strain of type 1 poliovirus at resolutions ranging from 3.8 to 6.3Å. All five VHHs bind deep in the virus canyon at similar sites that overlap extensively with the binding site for the receptor (CD155). The binding surfaces on the VHHs are surprisingly extensive, but despite the use of similar binding surfaces on the virus, the binding surface on the VHHs is unique for each VHH. In four of the five complexes, the virus remains essentially unchanged, but for the fifth there are significant changes reminiscent of but smaller in magnitude than the changes associated with cell entry, suggesting that this VHH traps the virus in a previously undescribed early intermediate state. The neutralizing mechanisms of the VHHs and their potential use as quality control agents for the end game of poliovirus eradication are discussed.
此前已筛选出识别1型脊髓灰质炎病毒的纳米抗体（或VHH），并将其表征为抗病毒剂候选物或疫苗质量控制标准化试剂。在本研究中，我们展示了脊髓灰质炎病毒与五种中和性VHH的高分辨率冷冻电镜重建结构。所有VHH均在衣壳峡谷中与广泛重叠脊髓灰质炎病毒受体结合位点的部位结合。相比之下，这五种VHH中的每一种与衣壳的相互作用都涉及一个独特（且惊人地广泛）的表面。发现衣壳的五个区域参与了与所有五种VHH的结合。已知这五个区域中的四个在与病毒进入相关的衣壳扩张过程中会发生变化。有趣的是，其中一种VHH（PVSS21E）的结合导致衣壳结构发生显著变化，因此似乎将病毒捕获在扩张的早期阶段。
我们描述了五种中和性VHH与1型脊髓灰质炎病毒马奥尼株复合物的冷冻电镜结构，分辨率在3.8至6.3埃之间。所有五种VHH均在病毒峡谷深处的相似位点结合，这些位点与受体（CD155）的结合位点广泛重叠。VHH上的结合表面惊人地广泛，但尽管在病毒上使用了相似的结合表面，但每个VHH的结合表面都是独特的。在五个复合物中的四个中，病毒基本保持不变，但在第五个复合物中，有显著变化，这些变化让人想起但幅度小于与细胞进入相关的变化，这表明这种VHH将病毒捕获在一个此前未描述的早期中间状态。讨论了VHH的中和机制及其作为脊髓灰质炎病毒根除最终阶段质量控制剂的潜在用途。
