From the Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, D.C.
Department of Pediatrics, Georgetown University Medical Center, Washington, D.C.; and.
Allergy Asthma Proc. 2022 Sep 1;43(5):419-430. doi: 10.2500/aap.2022.43.220045.
Secretory immunoglobulin A (sIgA) plays an important role in antiviral protective immunity. Although salivary testing has been used for many viral infections, including severe acute respiratory syndrome (SARS) and Middle East Respiratory Syndrome (MERS), its use has not yet been well established with the SARS coronavirus 2 (SARS-CoV-2). Quantification of salivary IgA and IgG antibodies can elucidate mucosal and systemic immune responses after natural infection or vaccination. Here, we report the development and validation of a rapid enzyme-linked immunosorbent assay (ELISA) for anti-SARS-CoV-2 salivary IgA and serum IgG antibodies, and present quantitative results for immunized subjects both prior to or following COVID-19 infections. Total and serum SARS-CoV-2 spike-specific IgG responses were compared with salivary spike-specific IgA and IgG responses in samples obtained from patients recently infected with SARS-CoV-2 and from subjects recently immunized with COVID-19 vaccines. A total of 52 paired saliva and serum samples were collected from 26 study participants: 7 subjects after COVID-19 infection and 19 subjects who were uninfected. The ELISA results from these samples were compared with five prepandemic control serum samples. Total IgG and SARS-CoV-2 spike-specific IgG in the serum samples from the subjects who were infected and vaccinated were also measured in a commercial laboratory with an enzyme immunoassay. A wide variation in antibody responses was seen in salivary and serum samples measured by both methods. Three groups of serum total and IgG spike-specific SARS-CoV-2 antibody responses were observed: (1) low, (2) intermediate, and (3) high antibody responders. A correlational analysis of salivary IgA (sIgA) responses with serum IgG concentrations showed a statistical correlation in the low and intermediate antibody responder groups but not in the high group (which we believe was a result of saturation). These preliminary findings suggest measuring salivary and serum IgG and IgA merit further investigation as markers of current or recent SARS-CoV-2 infections.
分泌型免疫球蛋白 A（sIgA）在抗病毒保护性免疫中发挥着重要作用。尽管唾液检测已被用于多种病毒感染，包括严重急性呼吸综合征（SARS）和中东呼吸综合征（MERS），但其在 SARS 冠状病毒 2（SARS-CoV-2）中的应用尚未得到充分确立。唾液 IgA 和 IgG 抗体的定量可以阐明自然感染或接种疫苗后的黏膜和全身免疫反应。在这里，我们报告了一种快速酶联免疫吸附测定（ELISA）检测 SARS-CoV-2 唾液 IgA 和血清 IgG 抗体的开发和验证，并提供了免疫接种受试者在 COVID-19 感染前后的定量结果。比较了来自最近感染 SARS-CoV-2 的患者和最近接种 COVID-19 疫苗的受试者的唾液和血清中总 SARS-CoV-2 刺突特异性 IgG 反应与唾液刺突特异性 IgA 和 IgG 反应。共收集了 26 名研究参与者的 52 对唾液和血清样本：7 名 COVID-19 感染后和 19 名未感染的参与者。用商业 ELISA 试剂盒检测这些样本的 ELISA 结果与 5 份大流行前的对照血清样本进行了比较。还在商业实验室用酶免疫测定法检测了感染和接种疫苗的受试者血清样本中的总 IgG 和 SARS-CoV-2 刺突特异性 IgG。用两种方法测量的唾液和血清样本中观察到抗体反应的广泛变化。观察到三种血清总 SARS-CoV-2 抗体和 IgG 刺突特异性 SARS-CoV-2 抗体反应组：（1）低，（2）中，和（3）高抗体应答者。唾液 IgA（sIgA）与血清 IgG 浓度的相关性分析显示，在低和中抗体应答者组中存在统计学相关性，但在高组中没有相关性（我们认为这是由于饱和所致）。这些初步发现表明，测量唾液和血清 IgG 和 IgA 作为当前或最近 SARS-CoV-2 感染的标志物值得进一步研究。
