Development of antibody protection during SARS-CoV-2 infection is a pressing question for public health and for vaccine development. We developed highly sensitive SARS-CoV-2-specific antibody and neutralization assays. SARS-CoV-2 Spike protein or Nucleocapsid protein specific IgG antibodies at titers more than 1:100,000 were detectable in all PCR+ subjects (n=115) and were absent in the negative controls. Other isotype antibodies (IgA, IgG1-4) were also detected. SARS-CoV-2 neutralization was determined in COVID-19 and convalescent plasma at up to 10,000-fold dilution, using Spike protein pseudotyped lentiviruses, which were also blocked by neutralizing antibodies (NAbs). Hospitalized patients had up to 3000-fold higher antibody and neutralization titers compared to outpatients or convalescent plasma donors. Interestingly, some COVID-19 patients also possessed NAbs against SARS-CoV Spike protein pseudovirus. Together these results demonstrate the high specificity and sensitivity of our assays, which may impact understanding the quality or duration of the antibody response during COVID-19 and in determining the effectiveness of potential vaccines.

中文翻译：

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新型 SARS-CoV-2 特异性抗体和中和试验揭示了 COVID-19 期间的广泛体液免疫反应。

在 SARS-CoV-2 感染期间开发抗体保护是公共卫生和疫苗开发的紧迫问题。我们开发了高度敏感的 SARS-CoV-2 特异性抗体和中和试验。在所有 PCR+ 受试者（n=115）中都可检测到滴度超过 1:100,000 的 SARS-CoV-2 刺突蛋白或核衣壳蛋白特异性 IgG 抗体，并且在阴性对照中不存在。还检测到其他同种型抗体（IgA、IgG1-4）。使用 Spike 蛋白假型慢病毒（也被中和抗体 (NAbs) 阻断）在 COVID-19 和恢复期血浆中以高达 10,000 倍的稀释度测定 SARS-CoV-2 中和作用。与门诊患者或恢复期血浆捐赠者相比，住院患者的抗体和中和滴度高达 3000 倍。有趣的是，一些 COVID-19 患者还拥有针对 SARS-CoV 刺突蛋白假病毒的 NAb。这些结果共同证明了我们检测的高特异性和敏感性，这可能会影响理解 COVID-19 期间抗体反应的质量或持续时间以及确定潜在疫苗的有效性。