Department of Anesthesiology, Stony Brook University Medical Center, Stony Brook, New York, USA.
Department of Pathology, Stony Brook University Medical Center, Stony Brook, New York, USA.
Transfusion. 2021 May;61(5):1363-1369. doi: 10.1111/trf.16283. Epub 2021 Feb 19.
There are limited data on the neutralizing activity of convalescent plasma (CP) administered in randomized controlled trials (RCT) of COVID-19 infection.
As part of an RCT, CP was collected per FDA guidelines from individuals recovered from COVID-19 infection. CP donors had to have ≥145 optical density (OD) units (ideal target ≥300) using a semiquantitative, immunochromatographic test for IgG antibody to the nucleocapsid protein (NP) of SARS-CoV-2 (typical range 0-500 OD units). A random subset of samples [14 control plasma, 12 CP "medium-anti-NP" (145-299 OD units), and 13 CP "high" anti-NP (≥300 OD units)] were tested for neutralizing antibodies using an established viral luciferase antibody inhibition assay to detect the infection of SARS-CoV-2 pseudovirus that encoded spike protein (SARS2-S ) on a human immunodeficiency virus 1 vector (NL43dEnvNanoLuc), using ACE2-expressing 293 T cells. The titer needed to neutralize 50% of viral activity (NT50) was calculated.
The uptake of SARS-CoV-2 pseudovirus by 293T cells was inhibited by pretreatment with CP compared to control CP (p < .001) with control plasma having a median (IQR) 50% neutralization titer (NT50) of 1:28 (1:16,1:36) compared to 1:334 (1:130,1:1295) and 1:324 (1:244,1:578), for medium anti-NP and high anti-NP CP units, respectively. The neutralizing activity of CP met minimum FDA criteria with neutralizing antibody titers >1:80 in 100% of randomly selected samples, using a conservative approach that excluded non-specific binding.
Plasma from donors screened using an immunochromatographic test for IgG antibody to SARS-CoV-2 NP exhibited neutralizing activity meeting FDA's minimum standard in all randomly selected COVID-19 CP units.
关于恢复期血浆（CP）在 COVID-19 感染的随机对照试验（RCT）中的中和活性，数据有限。
作为 RCT 的一部分，按照 FDA 指南从 COVID-19 感染中康复的个体中采集 CP。CP 供体必须使用半定量、免疫层析试验检测针对 SARS-CoV-2 核衣壳蛋白（NP）的 IgG 抗体，其光密度（OD）单位≥145（理想目标≥300）。一个随机的样本子集[14 个对照血浆、12 个“中抗-NP”CP（145-299 OD 单位）和 13 个“高抗-NP”CP（≥300 OD 单位）]，使用建立的病毒荧光素酶抗体抑制试验检测中和抗体，该试验检测编码刺突蛋白（SARS2-S）的 SARS-CoV-2 假病毒对人类免疫缺陷病毒 1 载体（NL43dEnvNanoLuc）的感染，使用表达 ACE2 的 293T 细胞。计算中和 50%病毒活性所需的滴度（NT50）。
与对照 CP 相比，CP 预处理可抑制 293T 细胞摄取 SARS-CoV-2 假病毒（p <.001），对照血浆的 50%中和滴度（NT50）中位数（IQR）为 1:28（1:16，1:36），而中抗-NP 和高抗-NP CP 单位的分别为 1:334（1:130，1:1295）和 1:324（1:244，1:578）。使用排除非特异性结合的保守方法，CP 的中和活性符合 FDA 的最低标准，随机选择的样本中 100%的中和抗体滴度>1:80。
使用 SARS-CoV-2 NP IgG 抗体免疫层析试验筛选的供体血浆在所有随机选择的 COVID-19 CP 单位中均表现出符合 FDA 最低标准的中和活性。
