Dynamic anti-spike protein antibody profiles in COVID-19 patients
Yu-Jie Bao, Yun Ling, Yingying Chen, Di Tian, Guoping Zhao, Xianghui Zhang, Hong Hang, Li Yu, Bing Su, Hongzhou Lu, Jie Xu, Ying Wang
Abstract
ObjectivesThis study intended to investigate the dynamics of anti-spike (S) IgG and IgM antibodies in COVID-19 patients.MethodsAnti-S IgG/IgM was determined by a semi-quantitative fluorescence immunoassay in the plasma of COVID-19 patients at the manifestation and rehabilitation stages. The immunoreactivity to full-length S proteins, C-terminal domain (CTD), and N-terminal domain (NTD) of S1 fragments were determined by an ELISA assay. Clinical properties at admission and discharge were collected simultaneously.ResultsThe positive rates of anti-S IgG/IgM in COVID-19 patients were elevated after rehabilitation compared to the in-patients. Anti-S IgG and IgM were not apparent until day 14 and day ten, respectively, according to Simple Moving Average analysis with five days’ slide window deduction. More than 90% of the rehabilitation patients exhibited IgG and IgM responses targeting CTD-S1 fragments. Decreased total peripheral lymphocytes, CD4+ and CD8+ T cell counts were seen in COVID-19 patients at admission and recovered after the rehabilitation.ConclusionsAnti-S IgG and IgM do not appear at the onset with the decrease in T cells, making early serological screening less significant. However, the presence of high IgG and IgM to S1-CTD in the recovered patients highlights humoral responses after SARS-CoV-2 infection, which might be associated with efficient immune protection in COVID-19 patients.