Paul-Ehrlich-Institut, Department of Virology, Paul-Ehrlich Street 51-59, D-63225 Langen, Germany.
Institute of Clinical Pharmacology, RWTH Aachen University Hospital Aachen, Pauwelsstraße 30, D-52074 Aachen, Germany.
Viruses. 2022 Feb 17;14(2):410. doi: 10.3390/v14020410.
In light of an increasing number of vaccinated and convalescent individuals, there is a major need for the development of robust methods for the quantification of neutralizing antibodies; although, a defined correlate of protection is still missing. Sera from hospitalized COVID-19 patients suffering or not suffering from acute respiratory distress syndrome (ARDS) were comparatively analyzed by plaque reduction neutralization test (PRNT) and pseudotype-based neutralization assays to quantify their neutralizing capacity. The two neutralization assays showed comparable data. In case of the non-ARDS sera, there was a distinct correlation between the data from the neutralization assays on the one hand, and enzyme-linked immune sorbent assay (ELISA), as well as biophysical analyses, on the other hand. As such, surface plasmon resonance (SPR)-based assays for quantification of binding antibodies or analysis of the stability of the antigen-antibody interaction and inhibition of syncytium formation, determined by cell fusion assays, were performed. In the case of ARDS sera, which are characterized by a significantly higher fraction of RBD-binding IgA antibodies, there is a clear correlation between the neutralization assays and the ELISA data. In contrast to this, a less clear correlation between the biophysical analyses on the one hand and ELISAs and neutralization assays on the other hand was observed, which might be explained by the heterogeneity of the antibodies. To conclude, for less complex immune sera-as in cases of non-ARDS sera-combinations of titer quantification by ELISA with inhibition of syncytium formation, SPR-based analysis of antibody binding, determination of the stability of the antigen-antibody complex, and competition of the RBD-ACE2 binding represent alternatives to the classic PRNT for analysis of the neutralizing potential of SARS-CoV-2-specific sera, without the requirement for a BSL3 facility.
鉴于越来越多的接种疫苗和康复个体，我们迫切需要开发强大的方法来定量中和抗体；尽管如此，仍然缺乏明确的保护相关因素。通过蚀斑减少中和试验（PRNT）和基于假型的中和测定法比较分析了来自患有或不患有急性呼吸窘迫综合征（ARDS）的住院 COVID-19 患者的血清，以定量其中和能力。两种中和测定法显示出可比的数据。在非 ARDS 血清的情况下，一方面中和测定法的数据与酶联免疫吸附测定（ELISA）以及另一方面的生物物理分析之间存在明显的相关性。因此，进行了基于表面等离子体共振（SPR）的测定法以定量结合抗体或分析抗原-抗体相互作用的稳定性和细胞融合测定法确定的合胞体形成的抑制作用。在 ARDS 血清的情况下，其特征是 RBD 结合 IgA 抗体的比例明显更高，中和测定法与 ELISA 数据之间存在明显的相关性。与此相反，一方面生物物理分析与另一方面的 ELISA 和中和测定法之间的相关性不太明显，这可能是由于抗体的异质性所致。总之，对于不太复杂的免疫血清（如非 ARDS 血清），ELISA 抑制合胞体形成的效价定量与 SPR 分析抗体结合、抗原-抗体复合物稳定性的测定以及 RBD-ACE2 结合的竞争相结合，代表了替代经典 PRNT 的方法用于分析 SARS-CoV-2 特异性血清的中和潜力，而无需 BSL3 设施。
