Replication Data for: Diagnostic Accuracy of an Immunoassay Using Avidity-Enhanced Polymeric Peptides for SARS-CoV-2 Antibody Detection

Diagnostic Accuracy of an Immunoassay Using Avidity-Enhanced Polymeric Peptides for SARS-CoV-2 Antibody Detection Background: There is a need for synthetic peptide-based serologic assays that exploit avidity to replace whole antigens while enabling low-cost diagnostics in resource-limited settings. Objective: To evaluate the diagnostic accuracy of a polymeric peptide-based ELISA leveraging avidity to enhance signal strength. Method: A 15-member SARS-CoV-2 peptide library corresponding to multiple epitope clusters and proteins was screened by indirect ELISA using pooled sera from RT-PCR-confirmed patients. The lead peptide candidate, S559, was identified and modified by terminal cysteine-substitution to enable disulfide-linked polymerization. Avidity gain was quantified by comparing the apparent dissociation constant (KDapp) of the polymerized vs. depolymerized forms, the latter achieved using N-acetylcysteine. An optimized ELISA based on S559 was evaluated on: 1,222 prospectively collected COVID-19 serum samples 218 biobanked negative controls Results: Polymeric S559 exhibited a 218% avidity gain relative to its depolymerized form, with a KDapp of 29.26 nM-1. Diagnostic performance of the optimized ELISA was: Sensitivity: 83.39% (95% CI: 81.18%–85.43%) Specificity: 96.79% (95% CI: 93.50%–98.70%) Using post hoc thresholds derived via the Youden Index: Sensitivity: 95.01% (95% CI: 93.63%–96.16%) Specificity: 100.00% (95% CI: 98.32%–100.00%) Conclusion: Homomultivalent epitope presentation using polymeric S559 enables a highly specific and sensitive immunoassay for detecting anti-SARS-CoV-2 antibodies. This method has potential utility in infection diagnosis, vaccine response monitoring, and seroepidemiologic surveillance. Contact: [e-mail]

应用亲和力增强聚合肽的免疫检测方法对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）抗体的诊断效能
背景：当前亟需开发基于合成肽的血清学检测方法，利用亲和力特性替代全抗原，同时在资源匮乏地区实现低成本诊断。
目的：评估基于聚合肽、利用亲和力增强信号强度的酶联免疫吸附试验（ELISA）的诊断效能。
方法：采用逆转录聚合酶链反应（RT-PCR）确认的患者混合血清，通过间接酶联免疫吸附试验（ELISA）筛选包含多个表位簇与蛋白的15组分SARS-CoV-2肽库。筛选得到核心肽候选物S559，并通过末端半胱氨酸修饰实现二硫键连接聚合。通过比较聚合态与解聚态形式的表观解离常数（KDapp）量化亲和力提升效果，其中解聚态通过N-乙酰半胱氨酸（N-acetylcysteine）处理获得。基于S559的优化型ELISA共开展以下样本检测：1222份前瞻性收集的COVID-19血清样本及218份冻存阴性对照样本。
结果：聚合态S559相较于解聚态亲和力提升218%，表观解离常数（KDapp）为29.26 nM⁻¹。该优化型ELISA的诊断性能如下：初始阈值下灵敏度为83.39%（95%置信区间：81.18%~85.43%），特异度为96.79%（95%置信区间：93.50%~98.70%）；基于尤登指数（Youden Index）推导的事后阈值下，灵敏度为95.01%（95%置信区间：93.63%~96.16%），特异度为100.00%（95%置信区间：98.32%~100.00%）。
结论：采用聚合态S559实现的同源多价表位呈递，可构建高特异度与高灵敏度的抗SARS-CoV-2抗体检测免疫检测方法。该方法在感染诊断、疫苗应答监测及血清流行病学监测中具有应用潜力。
联系方式：[e-mail]