Bruni Margherita, Cecatiello Valentina, Diaz-Basabe Angelica, Lattanzi Georgia, Mileti Erika, Monzani Silvia, Pirovano Laura, Rizzelli Francesca, Visintin Clara, Bonizzi Giuseppina, Giani Marco, Lavitrano Marialuisa, Faravelli Silvia, Forneris Federico, Caprioli Flavio, Pelicci Pier Giuseppe, Natoli Gioacchino, Pasqualato Sebastiano, Mapelli Marina, Facciotti Federica
Department of Experimental Oncology, European Institute of Oncology IRCCS, via Adamello 16, 20139 Milan, Italy.
Department of Oncology and Hemato-Oncology, University of Milan, via Festa del Perdono 7, 20122 Milan, Italy.
J Clin Med. 2020 Oct 1;9(10):3188. doi: 10.3390/jcm9103188.
Although antibody response to SARS-CoV-2 can be detected early during the infection, several outstanding questions remain to be addressed regarding the magnitude and persistence of antibody titer against different viral proteins and their correlation with the strength of the immune response. An ELISA assay has been developed by expressing and purifying the recombinant SARS-CoV-2 Spike Receptor Binding Domain (RBD), Soluble Ectodomain (Spike), and full length Nucleocapsid protein (N). Sera from healthcare workers affected by non-severe COVID-19 were longitudinally collected over four weeks, and compared to sera from patients hospitalized in Intensive Care Units (ICU) and SARS-CoV-2-negative subjects for the presence of IgM, IgG and IgA antibodies as well as soluble pro-inflammatory mediators in the sera. Non-hospitalized subjects showed lower antibody titers and blood pro-inflammatory cytokine profiles as compared to patients in Intensive Care Units (ICU), irrespective of the antibodies tested. Noteworthy, in non-severe COVID-19 infections, antibody titers against RBD and Spike, but not against the N protein, as well as pro-inflammatory cytokines decreased within a month after viral clearance. Thus, rapid decline in antibody titers and in pro-inflammatory cytokines may be a common feature of non-severe SARS-CoV-2 infection, suggesting that antibody-mediated protection against re-infection with SARS-CoV-2 is of short duration. These results suggest caution in using serological testing to estimate the prevalence of SARS-CoV-2 infection in the general population.
尽管在感染新型冠状病毒（SARS-CoV-2）的早期就能检测到抗体反应，但关于针对不同病毒蛋白的抗体滴度的大小和持久性及其与免疫反应强度的相关性，仍有几个重要问题有待解决。通过表达和纯化重组新型冠状病毒刺突受体结合域（RBD）、可溶性胞外域（刺突）和全长核衣壳蛋白（N），开发了一种酶联免疫吸附测定（ELISA）方法。对受非重症新型冠状病毒肺炎影响的医护人员的血清进行了为期四周的纵向收集，并与重症监护病房（ICU）住院患者和新型冠状病毒2阴性受试者的血清进行比较，以检测血清中IgM、IgG和IgA抗体以及可溶性促炎介质的存在情况。无论检测何种抗体，非住院受试者的抗体滴度和血液促炎细胞因子水平均低于重症监护病房（ICU）的患者。值得注意的是，在非重症新型冠状病毒肺炎感染中，病毒清除后一个月内，针对RBD和刺突的抗体滴度下降，但针对N蛋白的抗体滴度未下降，促炎细胞因子也减少。因此，抗体滴度和促炎细胞因子的快速下降可能是非重症新型冠状病毒感染的一个共同特征，这表明抗体介导的对新型冠状病毒再感染的保护作用持续时间较短。这些结果提示在使用血清学检测来估计普通人群中新型冠状病毒感染的患病率时应谨慎。
