Vilibic-Cavlek Tatjana, Bogdanic Maja, Borko Ema, Hruskar Zeljka, Zilic Denis, Ferenc Thomas, Tabain Irena, Barbic Ljubo, Vujica Ferenc Mateja, Ferencak Ivana, Stevanovic Vladimir
Department of Virology, Croatian Institute of Public Health, 10000 Zagreb, Croatia.
School of Medicine, University of Zagreb, 10000 Zagreb, Croatia.
Antibodies (Basel). 2023 May 10;12(2):35. doi: 10.3390/antib12020035.
Since sensitivity and specificity vary widely between tests, SARS-CoV-2 serology results should be interpreted with caution.
The study included serum samples from patients who had recovered from COVID-19 ( = 71), individuals vaccinated against SARS-CoV-2 ( = 84), and asymptomatic individuals ( = 33). All samples were tested for the presence of binding antibodies (enzyme immunoassay; EIA), neutralizing (NT) antibodies (virus neutralization test; VNT), and surrogate NT (sNT) antibodies (surrogate virus neutralization test; sVNT) of SARS-CoV-2.
SARS-CoV-2-binding antibodies were detected in 71 (100%) COVID-19 patients, 77 (91.6%) vaccinated individuals, and 4 (12.1%) control subjects. Among EIA-positive samples, VNT was positive (titer ≥ 8) in 100% of COVID-19 patients and 63 (75.0%) of the vaccinated individuals, while sVNT was positive (>30% inhibition) in 62 (87.3%) patients and 59 (70.2%) vaccinated individuals. The analysis of antibody levels showed a significant moderate positive correlation between EIA and VNT, a moderate positive correlation between EIA and sVNT, and a strong positive correlation between VNT and sVNT. The proportion of positive sVNT detection rate was associated with VNT titer. The lowest positivity (72.4%/70.8%) was detected in samples with low NT titers (8/16) and increased progressively from 88.2% in samples with titer 32 to 100% in samples with titer 256.
sVNT appeared to be a reliable method for the assessment COVID-19 serology in patients with high antibody levels, while false-negative results were frequently observed in patients with low NT titers.
由于不同检测方法的敏感性和特异性差异很大，严重急性呼吸综合征冠状病毒2（SARS-CoV-2）血清学检测结果的解读应谨慎。
本研究纳入了从冠状病毒病2019（COVID-19）中康复的患者（n = 71）、接种过SARS-CoV-2疫苗的个体（n = 84）和无症状个体（n = 33）的血清样本。所有样本均检测了SARS-CoV-2结合抗体（酶免疫测定；EIA）、中和（NT）抗体（病毒中和试验；VNT）和替代NT（sNT）抗体（替代病毒中和试验；sVNT）的存在情况。
在71例（100%）COVID-19患者、77例（91.6%）接种疫苗个体和4例（12.1%）对照受试者中检测到SARS-CoV-2结合抗体。在EIA阳性样本中，100%的COVID-19患者和63例（75.0%）接种疫苗个体的VNT呈阳性（滴度≥8），而62例（87.3%）患者和59例（70.2%）接种疫苗个体的sVNT呈阳性（抑制率>30%）。抗体水平分析显示，EIA与VNT之间存在显著的中度正相关，EIA与sVNT之间存在中度正相关，VNT与sVNT之间存在强正相关。sVNT阳性检出率与VNT滴度相关。在NT滴度较低（8/16）的样本中，阳性率最低（72.4%/70.8%），并从滴度为32的样本中的88.2%逐渐增加到滴度为256的样本中的100%。
sVNT似乎是评估抗体水平较高患者COVID-19血清学的可靠方法，而在NT滴度较低的患者中经常观察到假阴性结果。
