The coronavirus infectious disease 2019 (COVID-19), which is initiated by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has imposed critical challenges to global health. Understanding the kinetic of SARS-CoV-2-specific IgM and IgG responses in different subsets of COVID-19 patients is crucial to get insight into the humoral immune response elicited against the virus. We investigated IgM and IgG responses against SARS-CoV-2 nucleocapsid (N) and receptor-binding domain (RBD) of spike protein in two groups of recovered and deceased COVID-19 patients. The levels of IgM and IgG specific to N and RBD proteins were detected by ELISA. N- and RBD-specific IgM was higher in deceased patients in comparison with recovered patients, while there was no significant difference in N- and RBD-specific IgG between the two groups. A significant correlation was observed between IgG and IgM titers against RBD and N, in both groups of patients. These results argue against impaired antibody response in deceased COVID-19 patients.

中文翻译：

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康复和死亡的伊朗 COVID-19 患者对 SARS-CoV-2 抗原的不同抗体反应

由严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 引发的 2019 年冠状病毒传染病 (COVID-19) 对全球健康提出了严峻挑战。了解 COVID-19 患者不同亚群中 SARS-CoV-2 特异性 IgM 和 IgG 反应的动力学对于深入了解针对病毒引发的体液免疫反应至关重要。我们调查了两组康复和死亡 COVID-19 患者对 SARS-CoV-2 核衣壳 (N) 和刺突蛋白受体结合域 (RBD) 的 IgM 和 IgG 反应。通过ELISA检测对N和RBD蛋白特异的IgM和IgG水平。与康复患者相比，已故患者的 N 和 RBD 特异性 IgM 较高，而两组之间 N 和 RBD 特异性 IgG 没有显着差异。在两组患者中，观察到针对 RBD 和 N 的 IgG 和 IgM 滴度之间存在显着相关性。这些结果反对已故 COVID-19 患者的抗体反应受损。