Research Institute for Sport, Physical Activity and Leisure, Carnegie School of Sport, Leeds Beckett University, UK.
Department of Army Health and Performance Research, Andover, Hampshire, UK.
J Immunol Methods. 2023 Jul;518:113492. doi: 10.1016/j.jim.2023.113492. Epub 2023 May 16.
Detecting antibody responses following infection with SARS-CoV-2 is necessary for sero-epidemiological studies and assessing the role of specific antibodies in disease, but serum or plasma sampling is not always viable due to logistical challenges. Dried blood spot sampling (DBS) is a cheaper, simpler alternative and samples can be self-collected and returned by post, reducing risk for SARS-CoV-2 exposure from direct patient contact. The value of large-scale DBS sampling for the assessment of serological responses to SARS-CoV-2 has not been assessed in depth and provides a model for examining the logistics of using this approach to other infectious diseases. The ability to measure specific antigens is attractive for remote outbreak situations where testing may be limited or for patients who require sampling after remote consultation.
We compared the performance of SARS-CoV-2 anti-spike and anti-nucleocapsid antibody detection from DBS samples with matched serum collected by venepuncture in a large population of asymptomatic young adults (N = 1070) living and working in congregate settings (military recruits, N = 625); university students, N = 445). We also compared the effect of self-sampling (ssDBS) with investigator-collected samples (labDBS) on assay performance, and the quantitative measurement of total IgA, IgG and IgM between DBS eluates and serum.
Baseline seropositivity for anti-spike IgGAM antibody was significantly higher among university students than military recruits. Strong correlations were observed between matched DBS and serum samples in both university students and recruits for the anti-spike IgGAM assay. Minimal differences were found in results by ssDBS and labDBS and serum by Bland Altman and Cohen kappa analyses. LabDBS achieved 82.0% sensitivity and 98.2% specificity and ssDBS samples 86.1% sensitivity and 96.7% specificity for detecting anti-spike IgGAM antibodies relative to serum samples. For anti-SARS-CoV-2 nucleocapsid IgG there was qualitatively 100% agreement between serum and DBS samples and weak correlation in ratio measurements. Strong correlations were observed between serum and DBS-derived total IgG, IgA, and IgM.
This is the largest validation of DBS against paired serum for SARS-CoV-2 specific antibody measurement and we have shown that DBS retains performance from prior smaller studies. There were no significant differences regarding DBS collection methods, suggesting that self-collected samples are a viable sampling collection method. These data offer confidence that DBS can be employed more widely as an alternative to classical serology.
检测 SARS-CoV-2 感染后的抗体反应对于血清流行病学研究和评估特定抗体在疾病中的作用是必要的，但由于后勤挑战，血清或血浆采样并不总是可行的。干血斑采样（DBS）是一种更便宜、更简单的替代方法，并且可以由自我采集并通过邮寄返回，从而降低了直接接触患者导致 SARS-CoV-2 暴露的风险。大规模 DBS 采样对 SARS-CoV-2 血清反应评估的价值尚未得到深入评估，并为使用这种方法评估其他传染病的后勤工作提供了模型。能够测量特定抗原对于远程暴发情况很有吸引力，在这种情况下，测试可能受到限制，或者对于需要在远程咨询后进行采样的患者。
我们比较了在居住和工作在集体环境中的大量无症状年轻成年人（军事新兵，N=625；大学生，N=445）中，从 DBS 样本与通过静脉穿刺采集的匹配血清中检测 SARS-CoV-2 刺突和核衣壳抗体的性能。我们还比较了自我采样（ssDBS）与研究人员采集的样本（labDBS）对检测性能的影响，以及 DBS 洗脱液和血清之间总 IgA、IgG 和 IgM 的定量测量。
在大学生中，基线抗刺突 IgGAM 抗体的血清阳性率明显高于新兵。在大学生和新兵中，匹配的 DBS 和血清样本之间均观察到强烈的相关性。通过 Bland Altman 和 Cohen kappa 分析，ssDBS 和 labDBS 与血清之间的差异最小。与血清样本相比，labDBS 检测抗刺突 IgGAM 抗体的灵敏度为 82.0%，特异性为 98.2%，ssDBS 样本的灵敏度为 86.1%，特异性为 96.7%。对于抗 SARS-CoV-2 核衣壳 IgG，血清和 DBS 样本之间存在定性 100%的一致性，并且在比值测量中存在弱相关性。在血清和 DBS 衍生的总 IgG、IgA 和 IgM 之间观察到强烈的相关性。
这是最大规模的 DBS 与 SARS-CoV-2 特异性抗体测量的配对血清验证，我们已经表明 DBS 保留了先前较小研究的性能。关于 DBS 采集方法没有显著差异，这表明自我采集的样本是一种可行的采样采集方法。这些数据为 DBS 作为经典血清学的替代方法更广泛应用提供了信心。
