Mitigation of the COVID-19 pandemic requires an understanding of the antibody response to SARS-CoV-2. However, throughout the development of SARS-CoV-2 IgG antibody assays during the past year, cross-reactivity to other coronaviruses remained a question. To address these issues, we evaluated IgG in COVID-19 convalescent plasma samples for reactivity against three SARS-CoV-2 antigens including full-length spike, receptor binding domain, and the proximal extracellular fusion domain, and spike antigens from other coronaviruses (SARS-CoV, MERS-CoV, hCoV-HKU1, hCoV-OC43, hCoV-229E and hCoV-NL63) using the VaxArray Coronavirus SeroAssay which is a multiplexed antigen assay developed by InDevR Inc. These results were compared to two commercial SARS-CoV-2 IgG ELISAs targeting either the SARS-CoV-2 nucleocapsid or spike antigens and a live virus focus reduction neutralizing antibody test (FRNT). The VaxArray platform showed high specificity for detection of SARS-CoV-2 IgG, evident from lack of reactivity to SARS-CoV-2 antigens despite significant reactivity to endemic coronavirus antigens in pre-pandemic samples. SARS-CoV-2 IgG positive samples reacted weakly to SARS-CoV spike but not to MERS-CoV. While the VaxArray platform had overall comparable results to the spike and nucleocapsid IgG ELISAs, results were more similar to the spike antigen ELISA and the platform displayed a higher sensitivity and specificity than both ELISAs. Samples with FRNT titers below 1/23 reported negative on VaxArray, while positive samples on VaxArray had significantly higher neutralizing antibody titers. These results suggest that the VaxArray Coronavirus SeroAssay performs with high sensitivity and specificity for the detection of SARS-CoV-2 IgG, and positive results on the platform indicate SARS-CoV-2 neutralizing activity.

缓解 COVID-19 大流行需要了解对 SARS-CoV-2 的抗体反应。然而，在过去一年中 SARS-CoV-2 IgG 抗体检测的整个发展过程中，与其他冠状病毒的交叉反应性仍然是一个问题。为了解决这些问题，我们评估了 COVID-19 恢复期血浆样本中 IgG 对三种 SARS-CoV-2 抗原的反应性，包括全长刺突、受体结合域和近端细胞外融合域，以及来自其他冠状病毒（SARS）的刺突抗原-CoV、MERS-CoV、hCoV-HKU1、hCoV-OC43、hCoV-229E 和 hCoV-NL63）使用 VaxArray 冠状病毒血清检测，这是一种由 InDevR Inc. 开发的多重抗原检测。将这些结果与两种针对 SARS-CoV-2 核衣壳或刺突抗原的商业 SARS-CoV-2 IgG ELISA 和活病毒病灶减少中和抗体测试 (FRNT) 进行了比较。VaxArray 平台显示出检测 SARS-CoV-2 IgG 的高度特异性，尽管对大流行前样本中的地方性冠状病毒抗原具有显着反应性，但对 SARS-CoV-2 抗原缺乏反应性。SARS-CoV-2 IgG 阳性样本对 SARS-CoV 尖峰反应较弱，但对 MERS-CoV 没有反应。虽然 VaxArray 平台总体上与尖峰和核衣壳 IgG ELISA 的结果相当，但结果与尖峰抗原 ELISA 更相似，并且该平台显示出比两种 ELISA 更高的灵敏度和特异性。FRNT 滴度低于 1/23 的样品在 VaxArray 上报告为阴性，而 VaxArray 上的阳性样本具有显着更高的中和抗体滴度。这些结果表明 VaxArray 冠状病毒 SeroAssay 在检测 SARS-CoV-2 IgG 方面具有高灵敏度和特异性，平台上的阳性结果表明具有 SARS-CoV-2 中和活性。