During the COVID-19 pandemic, SARS-CoV-2 infected millions of people and claimed hundreds of thousands of lives. Virus entry into cells depends on the receptor binding domain (RBD) of the SARS-CoV-2 spike protein (S). Although there is no vaccine, it is likely that antibodies will be essential for protection. However, little is known about the human antibody response to SARS-CoV-2. Here we report on 149 COVID-19 convalescent individuals. Plasmas collected an average of 39 days after the onset of symptoms had variable half-maximal neutralizing titers ranging from undetectable in 33% to below 1:1000 in 79%, while only 1% showed titers >1:5000. Antibody cloning revealed expanded clones of RBD-specific memory B cells expressing closely related antibodies in different individuals. Despite low plasma titers, antibodies to three distinct epitopes on RBD neutralized at half-maximal inhibitory concentrations (IC50s) as low as single digit ng/mL. Thus, most convalescent plasmas obtained from individuals who recover from COVID-19 do not contain high levels of neutralizing activity. Nevertheless, rare but recurring RBD-specific antibodies with potent antiviral activity were found in all individuals tested, suggesting that a vaccine designed to elicit such antibodies could be broadly effective.

中文翻译：

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恢复期个体对SARS-CoV-2感染的趋同抗体反应。

在COVID-19大流行期间，SARS-CoV-2感染了数百万人，并夺去了数十万人的生命。病毒进入细胞取决于SARS-CoV-2突突蛋白（S）的受体结合域（RBD）。尽管没有疫苗，但抗体可能对保护至关重要。然而，关于人对SARS-CoV-2的抗体应答知之甚少。在这里，我们报告了149名COVID-19康复者。症状发作后平均39天收集的血浆具有最大的中和效价变化范围，从33％不可检测到79％以下的1：1000以下，而只有1％的效价> 1：5000。抗体克隆揭示了RBD特异性记忆B细胞的扩展克隆，在不同个体中表达密切相关的抗体。尽管血浆滴度较低，针对RBD上三个不同表位的抗体在低至一位数ng / mL的一半最大抑制浓度（IC50）下被中和。因此，从从COVID-19中恢复的个体获得的大多数恢复性血浆不包含高水平的中和活性。然而，在所有测试的个体中发现了具有有效抗病毒活性的稀有但反复出现的RBD特异性抗体，这表明旨在引发此类抗体的疫苗可能具有广泛的效力。