The severe COVID-19 pandemic drives the research toward the SARS-CoV-2 virion structure and the possible therapies against it. Here, we characterized the β-propiolactone inactivated SARS-CoV-2 virions using transmission electron microscopy (TEM) and atomic force microscopy (AFM). We compared the SARS-CoV-2 samples purified by two consecutive chromatographic procedures (size exclusion chromatography [SEC], followed by ion-exchange chromatography [IEC]) with samples purified by ultracentrifugation. The samples prepared using SEC and IEC retained more spikes on the surface than the ones prepared using ultracentrifugation, as confirmed by TEM and AFM. TEM showed that the spike (S) proteins were in the pre-fusion conformation. Notably, the S proteins could be recognized by specific monoclonal antibodies. Analytical TEM showed that the inactivated virions retained nucleic acid. Altogether, we demonstrated that the inactivated SARS-CoV-2 virions retain the structural features of native viruses and provide a prospective vaccine candidate.

中文翻译：

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β-丙内酯灭活严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 颗粒的结构表征

严重的 COVID-19 大流行推动了对 SARS-CoV-2 病毒粒子结构及其可能的治疗方法的研究。在这里，我们使用透射电子显微镜 (TEM) 和原子力显微镜 (AFM) 表征了 β-丙内酯灭活的 SARS-CoV-2 病毒粒子。我们将通过两个连续色谱程序（尺寸排阻色谱 [SEC]，然后是离子交换色谱 [IEC]）纯化的 SARS-CoV-2 样品与通过超速离心纯化的样品进行了比较。TEM 和 AFM 证实，使用 SEC 和 IEC 制备的样品比使用超速离心制备的样品在表面保留更多的尖峰。TEM 显示刺突 (S) 蛋白处于融合前构象。值得注意的是，S 蛋白可以被特异性单克隆抗体识别。分析 TEM 显示灭活的病毒粒子保留了核酸。总之，我们证明了灭活的 SARS-CoV-2 病毒粒子保留了天然病毒的结构特征，并提供了一种潜在的候选疫苗。