University of Copenhagen, Rigshospitalet, Department of Infectious Diseases, Copenhagen, Denmark.
Aalborg University Hospital, Department of Molecular Diagnostics, Aalborg, Denmark.
J Clin Microbiol. 2021 Sep 20;59(10):e0100121. doi: 10.1128/JCM.01001-21. Epub 2021 Jul 14.
The purpose of this study was to characterize the diagnostic performance of a newly developed enzyme-linked immunosorbent assay (ELISA) for detection of SARS-CoV-2 nucleocapsid protein (NP) in blood. Blood samples were collected during hospitalization of 165 inpatients with PCR-confirmed SARS-CoV-2 infection and from 505 outpatients predominantly with relevant symptoms of COVID-19 simultaneously with PCR testing. For the 143 inpatients who had their first blood sample collected within 2 weeks after PCR-confirmed infection, the diagnostic sensitivity of the ELISA was 91.6%. The mean NP concentration of the 131 ELISA-positive blood samples was 1,734 pg/ml (range, 10 to 3,840 pg/ml). An exponential decline in NP concentration was observed for 368 blood samples collected over the first 4 weeks after PCR-confirmed SARS-CoV-2 infection, and all blood samples taken later had an NP concentration below the 10-pg/ml diagnostic cutoff. The diagnostic sensitivity of the ELISA was 81.4% for the 43 blood samples collected from outpatients with a simultaneous positive PCR test, and the mean NP concentration of the 35 ELISA-positive samples was 157 pg/ml (range, 10 to 1,377 pg/ml). For the 462 outpatients with a simultaneous negative PCR test, the diagnostic specificity of the ELISA was 99.8%. In conclusion, the SARS-CoV-2 NP ELISA is a suitable laboratory diagnostic test for COVID-19, particularly for hospitals, where blood samples are readily available and screening of serum or plasma by ELISA can facilitate prevention of nosocomial infections and reduce the requirement for laborious swab sampling and subsequent PCR analysis to confirmatory tests only.
本研究旨在描述一种新开发的酶联免疫吸附试验（ELISA）用于检测血液中 SARS-CoV-2 核衣壳蛋白（NP）的诊断性能。在住院的 165 名经 PCR 确诊的 SARS-CoV-2 感染患者和 505 名主要有 COVID-19 相关症状的门诊患者中采集了血液样本，同时进行 PCR 检测。对于 143 名在 PCR 确诊感染后 2 周内首次采集血液样本的住院患者，ELISA 的诊断敏感性为 91.6%。131 份 ELISA 阳性血液样本的 NP 浓度平均值为 1734pg/ml（范围 10 至 3840pg/ml）。在 PCR 确诊 SARS-CoV-2 感染后的前 4 周内采集了 368 份血液样本，观察到 NP 浓度呈指数下降，此后采集的所有血液样本的 NP 浓度均低于 10pg/ml 的诊断截止值。对于同时进行阳性 PCR 检测的 43 份门诊患者血液样本，ELISA 的诊断敏感性为 81.4%，35 份 ELISA 阳性样本的 NP 浓度平均值为 157pg/ml（范围 10 至 1377pg/ml）。对于同时进行阴性 PCR 检测的 462 名门诊患者，ELISA 的诊断特异性为 99.8%。综上所述，SARS-CoV-2 NP ELISA 是 COVID-19 的一种合适的实验室诊断检测方法，特别是对于医院，那里容易获得血液样本，通过 ELISA 对血清或血浆进行筛查可以有助于预防医院感染，并减少对费力的拭子采样和随后仅进行 PCR 分析以进行确证检测的需求。
