Correlation of SARS-CoV-2 Nucleocapsid Antigen and RNA Concentrations in Nasopharyngeal Samples from Children and Adults Using an Ultrasensitive and Quantitative Antigen Assay.
Correlation of SARS-CoV-2 Nucleocapsid Antigen and RNA Concentrations in Nasopharyngeal Samples from Children and Adults Using an Ultrasensitive and Quantitative Antigen Assay.
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DOI：
10.1128/jcm.03077-20
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发表时间：
2021-03-19
影响因子：
9.4
通讯作者：
Sigal GB
中科院分区：
文献类型：
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作者：
Pollock NR;Savage TJ;Wardell H;Lee RA;Mathew A;Stengelin M;Sigal GB
通过PCR诊断COVID-19具有高灵敏度，但检测具有高循环阈值（CT）值的样本的实用性仍然存在争议。目前可用的SARS-CoV-2核衣壳抗原（Ag）快速诊断试验（RDTs）的灵敏度远低于PCR。通过PCR诊断COVID-19具有高灵敏度，但检测具有高循环阈值（CT）值的样本的实用性仍然存在争议。目前可用的SARS-CoV-2核衣壳抗原（Ag）快速诊断试验（RDTs）的灵敏度远低于PCR。临床鼻咽（NP）样本中Ag和RNA量的相关性尚不清楚。采用一种用于SARS-CoV-2核衣壳的超灵敏定量电化学发光免疫测定法（MSD S-PLEX SARS-CoV-2 N测定法），测定先前通过PCR检测的成人和儿童临床NP样本中的Ag。S-PLEX Ag检测试剂盒的检测限（LOD）为0.16 pg/ml，临界值为0.32 pg/ml。在临床NP样品（收集于3.0 ml培养基中）中测得的Ag浓度范围为小于160 fg/ml至2.7 μg/ml。对数转换的Ag浓度与CT值密切相关。在35例成人和101例儿童PCR阳性样本中，灵敏度分别为91%（95%置信区间，77 - 98%）和79%（70 - 87%）。在CT ≤35的样本中，灵敏度分别为100%（88 - 100%）和96%（88 - 99%）。在50例成人和40例儿童PCR阴性标本中，特异性分别为100%（93 - 100%）和98%（87 - 100%）。临床NP样品中的核衣壳浓度跨越8个数量级，并与RNA浓度（CT值）密切相关。在CT值≤35的儿童和成人样本中，S-PLEX Ag检测试剂盒的灵敏度为96 - 100%，特异性为98 - 100%。这些结果澄清了临床样本中的Ag浓度分布，为Ag RDT的性能提供了深入了解，并为COVID-19的诊断提供了新的方法。
Diagnosis of COVID-19 by PCR offers high sensitivity, but the utility of detecting samples with high cycle threshold (CT) values remains controversial. Currently available rapid diagnostic tests (RDTs) for SARS-CoV-2 nucleocapsid antigens (Ag) have sensitivity well below PCR. Diagnosis of COVID-19 by PCR offers high sensitivity, but the utility of detecting samples with high cycle threshold (CT) values remains controversial. Currently available rapid diagnostic tests (RDTs) for SARS-CoV-2 nucleocapsid antigens (Ag) have sensitivity well below PCR. The correlation of Ag and RNA quantities in clinical nasopharyngeal (NP) samples is unknown. An ultrasensitive, quantitative electrochemiluminescence immunoassay for SARS-CoV-2 nucleocapsid (the MSD S-PLEX SARS-CoV-2 N assay) was used to measure Ag in clinical NP samples from adults and children previously tested by PCR. The S-PLEX Ag assay had a limit of detection (LOD) of 0.16 pg/ml and a cutoff of 0.32 pg/ml. Ag concentrations measured in clinical NP samples (collected in 3.0 ml of media) ranged from less than 160 fg/ml to 2.7 μg/ml. Log-transformed Ag concentrations correlated tightly with CT values. In 35 adult and 101 pediatric PCR-positive samples, the sensitivities were 91% (95% confidence interval, 77 to 98%) and 79% (70 to 87%), respectively. In samples with a CT of ≤35, the sensitivities were 100% (88 to 100%) and 96% (88 to 99%), respectively. In 50 adult and 40 pediatric PCR-negative specimens, the specificities were 100% (93 to 100%) and 98% (87 to 100%), respectively. Nucleocapsid concentrations in clinical NP samples span 8 orders of magnitude and correlate closely with RNA concentrations (CT values). The S-PLEX Ag assay showed 96 to 100% sensitivity in samples from children and adults with CT values of ≤35, and a specificity of 98 to 100%. These results clarify Ag concentration distributions in clinical samples, providing insight into the performance of Ag RDTs and offering a new approach to diagnosis of COVID-19.