新冠感染者康复期血浆中高效价新冠病毒IgG抗体检测的ELISA试剂盒筛选

Determination of the ELISA kits for screening convalescence plasma with high potency of SARS-CoV-2 IgG

目的通过对ELISA-IgG试剂盒检测不同时期采集的单份康复期血浆及病毒中和实验检测不同效价的混合血浆的结果进行比较与分析,确定能用于高效价新冠病毒IgG抗体筛查的试剂盒。方法用A、B两种不同厂家ELISA-IgG试剂盒同时检测2020年2月~2022年1月采集的269份康复期血浆,分析两者结果的相关性及符合率,初步确定试剂盒;按照初步选定的试剂盒的系列稀释标准品效价,分档位制备5档混合血浆小样G4~G128,同时用厂家A和厂家B的ELISA试剂盒以及原始株、Omicron变异株BA.1和BA.2株的假病毒中和实验检测,分析结果的相关性,结合强阳性样品的孔外稀释倍数,确定可用于筛选高效价新冠病毒IgG抗体的试剂盒。结果以内控参考品B2为标准品,厂家A检测敏感度为1∶32,厂家B检测敏感度为1∶8,厂家A的检测敏感度是厂家B的4倍;两个试剂盒检测269份血浆结果的相关性Pearson r为0.9441,P<0.0001;初步选定敏感度较低的厂家B为备选试剂盒。混浆小样结果分析显示,厂家A结果与厂家B结果的相关性Pearson r为0.988,厂家A的ELISA-IgG结果与3株病毒中和抗体效价相关性r排序分别为原始株(0.978)>BA.2株(0.970)>BA.1株(0.799),厂家B的ELISA-IgG结果与3株病毒中和抗体效价相关性r排序分别为原始株(0.994)>BA.2株(0.968)>BA.1株(0.804);若以B2稀释2倍的样品为收浆标准,厂家B试剂盒的收浆合格率为55.4%(149/269),高于现用的厂家A试剂盒的收浆合格率47.2%(127/269),对于强阳性血浆,厂家B试剂盒对于样品的稀释倍数更低,更方便操作。结论厂家A和厂家B的ELISA-IgG试剂盒均符合新冠病毒株IgG抗体检测要求,其中厂家B的试剂盒更适用于高效价IgG抗体的筛选。

Objective To determine the ELISA kit for screening convalescence plasma with high potency of SARS-CoV-2 IgG by comparing and analyzing the plasma detection results of convalescent plasma collected in different periods via ELISA kits from two manufacturers and the results of mixed plasma with different potency via pseudovirus neutralization experiments.Methods Two ELISA kits from different manufacturers(named A,B)were used to detect the plasma of 269 convalescent patients collected from Feb.2020~Jan.2022.The correlation and concordance rate of the two results were analyzed to determine the kit preliminarily.According to the titers of diluted series of standard of the preliminary selected kit,5 mixed plasma samples(G4-G128)with different potency were prepared.The correlation of ELISA IgG results of product A/B,as well as the pseudovirus neutralization test of the original strain,Omicron mutant BA.1 and BA.2 strains were analyzed.Combined with the outside-well dilution mode of the strongly positive samples,the kit for high potency of SARS-CoV-2 IgG screening was determined.Results When the internal control reference B,was used as the standard,the detection sensitivity of product A and B was 1:32 vs 1:8;the detection sensitivity of product A was 4 times that of product B.The correlation Pearson r between the results given by two kits was 0.9441(P<0.0001).Product B with low sensitivity was primarily selected as an alternative kit.The ELISA IgG results of samples from mixed plasma showed that the order of correlation r between product A and B was 0.988.The correlation r between product A and neutralization antibody potency of the three viruses was originalization antibody potency of the three viruses was original strain(0.994)>BA.2(0.968)>BA.1(0.804).If twice-diluted B,was taken as the excellent standard,55.4%of product B met the criterion,while 47.2%of product A met.For positive plasma with high IgG potency,the product B kit required a lower dilution of the sample,which was more convenient to operate.Conclusion Both of the ELISA IgG kit from product A and B can be used to screen IgG antibodies of SARS-CoV-2,while product B is more suitable for screening positive plasma with high IgG potency.