Serological test is a valuable diagnostic tool for coronavirus disease 2019 (COVID-19). However, considerable improvements to these tests are needed, especially in the detection sensitivity. In this study, six recombinant nucleocapsid and spike proteins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were prepared and evaluated, including three prokaryotic expression nucleocapsid proteins (rN, rN1, rN2) and three eukaryotic expression spike proteins (rS1, rS-RBD, rS-RBD-mFc). The recombinant proteins with the highest ELISA titers (rS1 and rS-RBD-mFc) were selected to develop a double-antigen sandwich colloidal gold immunochromatography assay (GICA) to detect total antibodies against SARS-CoV-2. The clinical evaluation results showed that the sensitivity and specificity of GICA were 92.09% (419/455) and 99.44% (706/710), respectively. Moreover, a significant number (65.63%, 21/32) of COVID-19 patients with undetectable viral RNA were correctly diagnosed by the GICA method. In conclusion, the eukaryotic expression spike proteins (rS1 and rS-RBD-mFc) are more suitable than the prokaryotic expression nucleocapsid proteins for serological diagnosis of SARS-CoV-2. The proposed GICA for detection of total antibodies could be a powerful complement to the current RNA tests for COVID-19.

血清学检测是 2019 年冠状病毒病 (COVID-19) 的一种有价值的诊断工具。然而，需要对这些测试进行相当大的改进，特别是在检测灵敏度方面。本研究制备并评估了 6 种严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）的重组核衣壳和刺突蛋白，包括 3 种原核表达核壳蛋白（rN、rN1、rN2）和 3 种真核表达刺突蛋白（rS1 , rS-RBD, rS-RBD-mFc)。选择具有最高 ELISA 滴度的重组蛋白（rS1 和 rS-RBD-mFc）来开发双抗原夹心胶体金免疫色谱法（GICA），以检测针对 SARS-CoV-2 的总抗体。临床评价结果显示，GICA的敏感性和特异性分别为92.09%（419/455）和99.44%（706/710），分别。此外，通过 GICA 方法正确诊断出大量（65.63%，21/32）病毒 RNA 检测不到的 COVID-19 患者。总之，真核表达刺突蛋白（rS1和rS-RBD-mFc）比原核表达核衣壳蛋白更适合用于SARS-CoV-2的血清学诊断。提议的用于检测总抗体的 GICA 可能是对当前 COVID-19 RNA 测试的有力补充。