ジャーナル: J Virol / 年: 2017 タイトル: Beta-Propiolactone Inactivation of Coxsackievirus A16 Induces Structural Alteration and Surface Modification of Viral Capsids. 著者: Chen Fan / Xiaohua Ye / Zhiqiang Ku / Liangliang Kong / Qingwei Liu / Cong Xu / Yao Cong / Zhong Huang / 要旨: Beta-propiolactone (BPL) is an inactivating agent that is widely used in the vaccine industry. However, its effects on vaccine protein antigens and its mechanisms of action remain poorly understood. ...Beta-propiolactone (BPL) is an inactivating agent that is widely used in the vaccine industry. However, its effects on vaccine protein antigens and its mechanisms of action remain poorly understood. Here we present cryo-electron microscopy (cryo-EM) structures of BPL-treated coxsackievirus A16 (CVA16) mature virions and procapsids at resolutions of 3.9 Å and 6.5 Å, respectively. Notably, both particles were found to adopt an expanded conformation resembling the 135S-like uncoating intermediate, with characteristic features including an opened 2-fold channel, the externalization of the N terminus of VP1 capsid protein, and the absence of pocket factor. However, major neutralizing epitopes are very well preserved on these particles. Further biochemical analyses revealed that BPL treatment impairs the abilities of CVA16 particles to bind to the attachment receptor heparan sulfate and to a conformation-dependent monoclonal antibody in a BPL dose-dependent manner, indicating that BPL is able to modify surface-exposed amino acid residues. Taken together, our results demonstrate that BPL treatment may induce alteration of the overall structure and surface properties of a nonenveloped viral capsid, thus revealing a novel mode of action of BPL. Beta-propiolactone (BPL) is commonly used as an inactivating reagent to produce viral vaccines. It is recognized that BPL inactivates viral infectivity through modification of viral nucleic acids. However, its effect on viral proteins remains largely unknown. Here, we present high-resolution cryo-EM structures of BPL-treated coxsackievirus A16 (CVA16) mature virions and procapsids, which reveals an expanded overall conformation and characteristic features that are typical for the 135S-like uncoating intermediate. We further show that the BPL concentration affects the binding of inactivated CVA16 particles to their receptor/antibody. Thus, BPL treatment can alter the overall structure and surface properties of viral capsids, which may lead to antigenic and immunogenic variations. Our findings provide important information for future development of BPL-inactivated vaccines.
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 120 K / 装置: FEI VITROBOT MARK III / 詳細: blot for 2 seconds.
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電子顕微鏡法
顕微鏡
FEI TITAN KRIOS
温度
最低: 70.0 K / 最高: 90.0 K
特殊光学系
球面収差補正装置: Microscope was modified with a Cs corrector
撮影
フィルム・検出器のモデル: FEI FALCON II (4k x 4k) 検出モード: INTEGRATING / デジタル化 - 画像ごとのフレーム数: 3-18 / 撮影したグリッド数: 1 / 実像数: 1350 / 平均露光時間: 1.1 sec. / 平均電子線量: 25.0 e/Å2 詳細: Images were recorded on a Falcon II direct electron detector in the 18-frame movie mode.
ソフトウェア - 名称: jspr ソフトウェア - 詳細: CTF fitting was automatically performed using fitctf2.py program in jspr 詳細: CTF fitting was automatically performed using fitctf2.py program in jspr
初期モデル
モデルのタイプ: INSILICO MODEL In silico モデル: The data we performed the reference-free 2D analysis and initial model building utilizing EMAN2.1 詳細: The data we performed the reference-free 2D analysis and initial model building utilizing EMAN2.1
最終 再構成
想定した対称性 - 点群: I (正20面体型対称) / アルゴリズム: FOURIER SPACE / 解像度のタイプ: BY AUTHOR / 解像度: 3.9 Å / 解像度の算出法: FSC 0.143 CUT-OFF / ソフトウェア - 名称: jspr 詳細: In the 3D reconstruction process, the gold standard procedure was followed using jspr package 使用した粒子像数: 25610