目的  初步建立抗新型冠状病毒受体结合域（receptor-binding domain, RBD)IgG定量ELISA检测方法，用于COVID-19静注人免疫球蛋白的研制中原料血浆、原液和成品的效价检测。方法  将已知的具有中和活性的COVID-19康复者恢复期血浆作为参比标准品，选用RBD抗原包被的间接ELISA试剂盒,采用双对数拟合曲线建立定量ELISA，确定其最佳线性范围；制备室内质控品，并对其进行标定；对该方法进行稀释线性、平行性、准确度、精密度验证。用建立的方法对3批COVID-19静注人免疫球蛋白的原料血浆、原液及成品进行检测，并与化学发光法及中和实验结果进行相关性分析。结果  确定标准曲线线性范围为稀释倍数1～8、批内准确度88.50%~108.58%，批间准确度100.63%~103.98%；批内精密度3.83%~14.68%，批间精密度5.67%~13.15%；标准品和原料血浆、原液、半成品的平行性好。ELISA效价与化学发光及中和实验相关性较好。结论  成功建立抗新型冠状病毒RBD-IgG定量ELISA检测方法，可用于COVID-19静注人免疫球蛋白的效价检测，作为内部放行方法。

 Objective  To establish the enzyme-linked quantitative detection method of anti-2019-nCoV neutralizing antibody for test of convalescent plasma, plasma bluk and final products in the development of COVID-19 human immunoglobulin for intravenous use. Methods  Using COVID-19 convalescent plasma with a known neutralizing activity as a reference standard,  the indirect ELISA kit coated with receptor-binding domain antigen was selected, and double log-fit curve was used to establish a quantitative ELISA, and its optimal linear range was determined.Indoor quality control was prepared and calibrated. Dilution linearity, parallelism, accuracy, precision of the method were verified. Three batches of convalescent plasma, plasma bluk and final products were tested by the method, and the correlation with the results of chemiluminescence immunoassay and neutralization experiment was analyzed. Results The standard curve range was determined as dilution factor 1-8. The intra-batch accuracy was 88.50% ~ 108.58%. The inter-batch accuracy was 100.98% ~ 103.98%. The intra-batch precision was within 3.83% ~ 14.68%. The inter-batch precision was 5.67% ~ 13.15%. Parallelism of standard substance with convalescent plasma, plasma bluk and final products good. Correlation of the method with chemiluminescence immunoassay and neutralization experiment was good. Conclusions  The method established meets the requirements, and can be used for the potency test of COVID-19 human intravenous immunoglobulin as an internal release test.