新型冠状病毒原始株和流行株IgG抗体组合识别Omicron BA.5流行株感染的研究

Application of IgG antibody combination of wild strain and epidemic strain of COVID-19 in identifying epidemic Omicron BA.5 strain infection

目的探讨新型冠状病毒特异性IgG抗体组合在识别Omicron BA.5流行株感染的应用。方法选择新冠高强度流行后的Omicron BF.7/BA.5自然感染人群、疫苗免后健康人群和免疫突破感染Omicron BF.7/BA.5病例为研究对象,应用间接ELISA法检测血清原始株和流行株特异性IgG抗体滴度,并比较不同人群血清特异性IgG抗体水平。应用ROC曲线探索新型冠状病毒原始型Spike IgG抗体(WT-S-IgG)和新型冠状病毒Spike(Omicron BA.5)IgG抗体(BA.5-S-IgG)两种抗体滴度以及两种抗体滴度比值在识别流行Omicron BA.5株感染中的应用价值,为病原体诊断提供技术支撑。结果免疫突破感染Omicron BF.7/BA.5病例的WT-S-IgG和BA.5-S-IgG两种抗体滴度水平明显高于Omicron BF.7/BA.5自然感染人群和疫苗免后健康人群(均P<0.05)。WT-S-IgG和BA.5-S-IgG抗体识别Omicron BA.5流行株感染ROC曲线下面积分别为0.947和0.961。BA.5-S-IgG与WT-S-IgG抗体滴度比值识别流行株感染AUC为0.873,当该比值为0.855时,灵敏度及特异度分别为80%和90%。按照感染者的感染后时长分类,BA.5-S-IgG与WT-S-IgG抗体滴度的比值识别≤30 d和>30 d流行株感染的ROC曲线下面积分别为0.887和0.863,灵敏度和特异度均达到80%以上。结论BA.5-S-IgG和WT-S-IgG两种血清抗体滴度及其比值在识别Omicron BA.5流行株感染具有较高应用价值。

Objective To explore the application of COVID-19-specific IgG antibody in identifying epidemic Omicron BA.5 strain infection.Method Omicron BF.7/BA.5 naturally infected population,healthy population vaccinated with the COVID-19 vaccine,and Omicron BF.7/BA.5 breakthrough cases were enrolled into this study.The serum WT-S-IgG and BA.5-S-IgG were detected by indirect ELISA,and the serum-specific IgG antibody levels of different populations were compared.The application value of the two antibody titers and the ratio of the two antibodies in identifying Omicron BA.5 epidemic strain infection were explored by the ROC curve,aiming to provide technical support for pathogen diagnosis.Results The antibody titers of WT-S-IgG and BA.5-S-IgG in the breakthrough cases were higher than those in the naturally infected population and the healthy population(P<0.05).The area under the curve(AUC)of WT-S-IgG and BA.5-S-IgG in identifying epidemic Omicron BA.5 strain infection was 0.947 and 0.961,respectively.The AUC of BA.5-S-IgG and WT-S-IgG antibody titer ratio was 0.873.When the antibody titer ratio was 0.855,the sensitivity and specificity were 80.00% and 90.00%,respectively.According to the interval since the last infection,the AUC of the ratio of BA.5-S-IgG to WT-S-IgG antibody titer to identify the infection of epidemic strains less than 30 days and more than 30 days was 0.887 and 0.863,respectively,and the sensitivity and specificity were both above 80%.Conclusion Both BA.5-S-IgG and WT-S-IgG,as well as the combination of these two antibodies,are of high value in the identification of epidemic strains.