SARS-CoV-2中和抗体活性评估方法研究

he pandemic caused by the novel coronavirus SARS-CoV-2 has not completely ended. Establishing effective immunity against the virus through vaccination is still the key measure for individual protection, and the activity of neutralizing antibodies in circulation is an important marker of the vaccine-induced immunity in individuals. In this work, we developed a novel method for rapid evaluation of neutralizing activity of SARS-CoV-2 antibodies, based on the specific interactions between the spike (S) protein of the virus and the ACE2 receptor of host cells. In this method, the receptor binding motif (RBM) of the S protein was covalently conjugated with a reporter DNA to form a hybrid amplification probe (RBM-DNA) for quantitative PCR analysis, while a pentameric RBM-binding protein (2B-LCB1) was constructed, which was further immobilized on the magnetic beads as a rapid capturer (Mag-LCB1) of RBM-DNA probes. Finally, the interaction between RBM-DNA and Mag-LCB1 was quantatively determiend by qPCR analysis, based on which the activty of neutralization antibodies can be indirectly quantified. The assay validation data showed that this assay was able to estimate the activity of serum neutralization antibodies from vaccinated individuals, and the limit of detection (LOD) for the neutralizing antibody was 4.05 μg/mL. In summary, this work provided a novel method for detecting the immune activities of SARS-CoV-2 neutralizing antibodies, and we envisage that it will prove to be an useful tool for evaluating vaccine-induced immunity of individuals in the post-pandemic era.