Gonoshasthaya-RNA Molecular Diagnostic and Research Center, Dhaka, 1205, Bangladesh.
Department of Pharmacy, BRAC University, Dhaka, 1212, Bangladesh.
Int J Nanomedicine. 2021 Jul 9;16:4739-4753. doi: 10.2147/IJN.S313140. eCollection 2021.
BACKGROUND: Serological tests detecting severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are widely used in seroprevalence studies and evaluating the efficacy of the vaccination program. Some of the widely used serological testing techniques are enzyme-linked immune-sorbent assay (ELISA), chemiluminescence immunoassay (CLIA), and lateral flow immunoassay (LFIA). However, these tests are plagued with low sensitivity or specificity, time-consuming, labor-intensive, and expensive. We developed a serological test implementing flow-through dot-blot assay (FT-DBA) for SARS-CoV-2 specific IgG detection, which provides enhanced sensitivity and specificity while being quick to perform and easy to use. METHODS: SARS-CoV-2 antigens were immobilized on nitrocellulose membrane to capture human IgG, which was then detected with anti-human IgG conjugated gold nanoparticle (hIgG-AuNP). A total of 181 samples were analyzed in-house. Within which 35 were further evaluated in US FDA-approved CLIA Elecsys SARS-CoV-2 assay. The positive panel consisted of RT-qPCR positive samples from patients with both <14 days and >14 days from the onset of clinical symptoms. The negative panel contained samples collected from the pre-pandemic era dengue patients and healthy donors during the pandemic. Moreover, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FT-DBA were evaluated against RT-qPCR positive sera. However, the overall efficacies were assessed with sera that seroconverted against either nucleocapsid (NCP) or receptor-binding domain (RBD). RESULTS: In-house ELISA selected a total of 81 true seropositive and 100 seronegative samples. The sensitivity of samples with <14 days using FT-DBA was 94.7%, increasing to 100% for samples >14 days. The overall detection sensitivity and specificity were 98.8% and 98%, respectively, whereas the overall PPV and NPV were 99.6% and 99%. Moreover, comparative analysis between in-house ELISA assays and FT-DBA revealed clinical agreement of Cohen's Kappa value of 0.944. The FT-DBA showed sensitivity and specificity of 100% when compared with commercial CLIA kits. CONCLUSION: The assay can confirm past SARS-CoV-2 infection with high accuracy within 2 minutes compared to commercial CLIA or in-house ELISA. It can help track SARS-CoV-2 disease progression, population screening, and vaccination response. The ease of use of the assay without requiring any instruments while being semi-quantitative provides the avenue of its implementation in remote areas around the globe, where conventional serodiagnosis is not feasible.
背景:血清学检测技术可用于检测严重急性呼吸综合征冠状病毒 2(SARS-CoV-2),广泛应用于血清流行率研究和评估疫苗接种计划的效果。一些常用的血清学检测技术包括酶联免疫吸附测定(ELISA)、化学发光免疫测定(CLIA)和侧向流动免疫测定(LFIA)。然而,这些检测方法存在灵敏度或特异性低、耗时、劳动强度大、成本高的问题。我们开发了一种用于 SARS-CoV-2 特异性 IgG 检测的血清学检测方法,即流动式点印迹分析(FT-DBA),该方法具有增强的灵敏度和特异性,同时快速、易于操作。
方法:SARS-CoV-2 抗原固定在硝酸纤维素膜上以捕获人 IgG,然后用人 IgG 结合的金纳米颗粒(hIgG-AuNP)进行检测。共分析了 181 个内部样本。其中 35 个样本进一步在美国食品药品监督管理局(FDA)批准的 CLIA Elecsys SARS-CoV-2 检测中进行了评估。阳性组包括从发病后<14 天和>14 天的患者 RT-qPCR 阳性样本。阴性组包含从登革热流行前时期采集的登革热患者和大流行期间的健康供体样本。此外,还评估了 FT-DBA 的灵敏度、特异性、阳性预测值(PPV)和阴性预测值(NPV)与 RT-qPCR 阳性血清的关系。然而,我们用针对核衣壳(NCP)或受体结合域(RBD)发生血清转换的血清评估了总体疗效。
结果:内部 ELISA 共选择了 81 个真正的血清阳性和 100 个血清阴性样本。使用 FT-DBA 检测<14 天的样本的灵敏度为 94.7%,检测>14 天的样本灵敏度增加到 100%。总的检测灵敏度和特异性分别为 98.8%和 98%,总的阳性预测值和阴性预测值分别为 99.6%和 99%。此外,内部 ELISA 检测与 FT-DBA 之间的比较分析显示,Cohen's Kappa 值的临床一致性为 0.944。FT-DBA 与商业 CLIA 试剂盒相比,灵敏度和特异性均为 100%。
结论:与商业 CLIA 或内部 ELISA 相比,该检测方法可在 2 分钟内准确确认过去的 SARS-CoV-2 感染。它有助于跟踪 SARS-CoV-2 疾病的进展、人群筛查和疫苗接种反应。该检测方法操作简单,无需任何仪器,具有半定量的特点,为在全球偏远地区实施提供了可能,而在这些地区,常规血清诊断是不可行的。
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