Albecka Anna, Clift Dean, Vaysburd Marina, Rhinesmith Tyler, Caddy Sarah L, Favara David M, Baxendale Helen E, James Leo C
MRC Laboratory of Molecular Biology, Protein & Nucleic Acid Division, Cambridge, UK.
CITIID, Department of Medicine, University of Cambridge, Cambridge, UK.
EMBO J. 2021 Sep 1;40(17):e108588. doi: 10.15252/embj.2021108588. Epub 2021 Jul 29.
The humoral immune response to SARS-CoV-2 results in antibodies against spike (S) and nucleoprotein (N). However, whilst there are widely available neutralization assays for S antibodies, there is no assay for N-antibody activity. Here, we present a simple in vitro method called EDNA (electroporated-antibody-dependent neutralization assay) that provides a quantitative measure of N-antibody activity in unpurified serum from SARS-CoV-2 convalescents. We show that N antibodies neutralize SARS-CoV-2 intracellularly and cell-autonomously but require the cytosolic Fc receptor TRIM21. Using EDNA, we show that low N-antibody titres can be neutralizing, whilst some convalescents possess serum with high titres but weak activity. N-antibody and N-specific T-cell activity correlates within individuals, suggesting N antibodies may protect against SARS-CoV-2 by promoting antigen presentation. This work highlights the potential benefits of N-based vaccines and provides an in vitro assay to allow the antibodies they induce to be tested.
对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）的体液免疫反应会产生针对刺突蛋白（S）和核蛋白（N）的抗体。然而，虽然有针对S抗体的广泛可用的中和试验，但尚无针对N抗体活性的试验。在此，我们提出了一种名为EDNA（电穿孔抗体依赖性中和试验）的简单体外方法，该方法可对SARS-CoV-2康复者未纯化血清中的N抗体活性进行定量测量。我们发现，N抗体在细胞内和细胞自主的情况下中和SARS-CoV-2，但需要胞质Fc受体TRIM21。使用EDNA，我们发现低N抗体滴度也可具有中和作用，而一些康复者的血清滴度高但活性弱。个体内N抗体和N特异性T细胞活性相关，这表明N抗体可能通过促进抗原呈递来抵御SARS-CoV-2。这项工作突出了基于N的疫苗的潜在益处，并提供了一种体外试验方法来检测它们诱导产生的抗体。
