Background Serological confirmation of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical for understanding the dynamics of the pandemic and determining seroprevalence rates within afflicted communities. Common challenges with SARS-CoV-2 serological assays include poor analytical specificity and sensitivity and lack of a serological standard for quantitative assessment of antibody titers. Methods To overcome these obstacles, we developed a quantitative enzyme-linked immunosorbent assay based on an optimized 2-dimensional screening assay that utilizes SARS-CoV-2 receptor binding domain (RBD) of spike protein and SARS-CoV-2 spike S1 subunit. Results A total of 4 SARS-CoV-2-reactive monoclonal antibodies were evaluated for use as serum standards for calibrating assays performed on different days or by different laboratories. This approach provided quantitative analysis of hospitalized reverse transcription polymerase chain reaction–confirmed COVID-19 cases that in some cases reached >100 μg/mL. The assay demonstrated 72% sensitivity based on time points ranging from 2 to 52 days post–symptom onset, with 100% sensitivity at time points measured ≥13 days post–symptom onset and 100% specificity. Conclusions Using these optimized reagents and serological standards, we believe this approach will be useful for sensitive and specific determination of seroconversion rates and quantitatively measuring the durability of antiviral antibody responses following SARS-CoV-2 infection or vaccination.

中文翻译：

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在低发病率环境中建立用于 SARS-CoV-2 定量血清学诊断的单克隆抗体标准

背景 由严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2) 引起的 2019 年冠状病毒病 (COVID-19) 的血清学确认对于了解大流行的动态和确定受影响社区的血清阳性率至关重要。SARS-CoV-2 血清学检测的常见挑战包括分析特异性和敏感性差，以及缺乏定量评估抗体滴度的血清学标准。方法为了克服这些障碍，我们开发了一种基于优化的二维筛选试验的定量酶联免疫吸附试验，该试验利用刺突蛋白的 SARS-CoV-2 受体结合域 (RBD) 和 SARS-CoV-2 刺突 S1 亚基。结果 总共评估了 4 种 SARS-CoV-2 反应性单克隆抗体作为血清标准，用于校准在不同日期或由不同实验室进行的测定。这种方法提供了对住院逆转录聚合酶链反应确诊的 COVID-19 病例的定量分析，这些病例在某些情况下达到了 > 100 μg/mL。根据症状发作后 2 至 52 天的时间点，该测定显示 72% 的灵敏度，在症状发作后≥13 天测量的时间点具有 100% 的灵敏度和 100% 的特异性。结论 使用这些优化的试剂和血清学标准，