Department of Laboratory Medicine, Clinique Saint-Luc Bouge, Namur, Belgium.
Department of Pharmacy, Namur Research Institute for Lifes Sciences, University of Namur, Namur, Belgium.
Clin Chem Lab Med. 2020 Dec 21;59(5):971-978. doi: 10.1515/cclm-2020-1652. Print 2021 Apr 27.
Accurate SARS-CoV-2 serological assays are urgently needed to help diagnose infection, determine past exposure of populations and assess the response to future vaccines. The study aims at assessing the performance of the multiplex D-tek COVIDOT 5 IgG assay for the detection of SARS-CoV-2 IgG antibodies (N, S1+S2, S1, S2 and RBD).
Sensitivity and dynamic trend to seropositivity were evaluated in 218 samples obtained from 46 rRT-PCR confirmed COVID-19 patients. Non-SARS-CoV-2 sera (n=118) collected before the COVID-19 pandemic with a potential cross-reaction to the SARS-CoV-2 immunoassay were included in the specificity analysis.
A gradual dynamic trend since symptom onset was observed for all IgG antibodies. Sensitivities before day 14 were suboptimal. At ≥21 days, sensitivities reached 100% (93.4-100%) for N, S1+S2, S2 and RBD-directed IgG and 96.3% (87.3-99.6%) for S1-directed IgG. In 42 out of 46 patients (91.3%), all five antibodies were detected at ≥14 days. The four remaining patients had between 2 and 4 positive antibodies at their respective maximal follow-up period. The specificity was 100 % for S1+S2, S2 and RBD, 98.3% for N and 92.4% (86.0-96.5%) for S1-directed IgG. The combined use of antigens increases the early sensitivity whilst enforcing high specificity.
Sensitivities at ≥21 days and specificities were excellent, especially for N, S1+S2, S2 and RBD-directed IgG. Caution is however required when interpreting single S1-directed reactivities. Using a multiplex assay complies with the orthogonal testing algorithm of the CDC and allows a better and critical interpretation of the serological status of a patient.
准确的 SARS-CoV-2 血清学检测对于帮助诊断感染、确定人群的既往暴露情况以及评估未来疫苗的反应至关重要。本研究旨在评估 D-tek COVIDOT 5 IgG 多重检测试剂盒检测 SARS-CoV-2 IgG 抗体（N、S1+S2、S1、S2 和 RBD）的性能。
在 46 例经 rRT-PCR 确诊的 COVID-19 患者的 218 份样本中评估了敏感性和血清阳性率的动态趋势。非 SARS-CoV-2 血清（n=118）在 COVID-19 大流行前采集，可能与 SARS-CoV-2 免疫检测有交叉反应，包括在特异性分析中。
所有 IgG 抗体均呈现出自症状出现以来的逐渐动态趋势。在第 14 天之前的敏感性欠佳。在≥21 天，N、S1+S2、S2 和 RBD 靶向 IgG 的敏感性达到 100%（93.4-100%），S1 靶向 IgG 的敏感性达到 96.3%（87.3-99.6%）。在 46 例患者中的 42 例（91.3%），在≥14 天的时间内检测到了所有五种抗体。其余 4 名患者在各自的最大随访期内有 2 至 4 种阳性抗体。S1+S2、S2 和 RBD 的特异性为 100%，N 的特异性为 98.3%，S1 靶向 IgG 的特异性为 92.4%（86.0-96.5%）。同时使用抗原可提高早期敏感性，同时保持高特异性。
在≥21 天的敏感性和特异性都非常好，尤其是针对 N、S1+S2、S2 和 RBD 靶向 IgG。但是，当解释单个 S1 靶向反应时需要谨慎。使用多重检测符合 CDC 的正交检测算法，并允许对患者的血清学状态进行更好和更关键的解释。
