Memory B cells specific for SARS-CoV-2 spike and nucleocapsid proteins persist in peripheral blood after recovery from COVID-19. Lasting immunity following SARS-CoV-2 infection is questioned because serum antibodies decline in convalescence. However, functional immunity is mediated by long-lived memory T and B (Bmem) cells. Therefore, we generated fluorescently-labeled tetramers of the spike receptor binding domain (RBD) and nucleocapsid protein (NCP) to determine the longevity and immunophenotype of SARS-CoV-2-specific Bmem cells in COVID-19 patients. A total of 36 blood samples were obtained from 25 COVID-19 patients between 4 and 242 days post-symptom onset including 11 paired samples. While serum IgG to RBD and NCP was identified in all patients, antibody levels began declining at 20 days post-symptom onset. RBD- and NCP-specific Bmem cells predominantly expressed IgM + or IgG1 + and continued to rise until 150 days. RBD-specific IgG + Bmem were predominantly CD27 + , and numbers significantly correlated with circulating follicular helper T cell numbers. Thus, the SARS-CoV-2 antibody response contracts in convalescence with persistence of RBD- and NCP-specific Bmem cells. Flow cytometric detection of SARS-CoV-2-specific Bmem cells enables detection of long-term immune memory following infection or vaccination for COVID-19.
【초록키워드】 COVID-19, IgM, vaccination, Immunity, antibody, SARS-COV-2 infection, Antibody Response, Infection, B cells, memory B cells, nucleocapsid protein, Receptor binding domain, memory, Peripheral blood, T cell, cells, immunophenotype, RBD, persistence, convalescence, antibody levels, serum antibody, Longevity, patients, COVID-19 patients, IgG1, memory B cell, SARS-CoV-2 spike, CD27, COVID-19 patient, Flow, symptom onset, Spike receptor binding domain, Blood samples, post-symptom onset, blood sample, Nucleocapsid proteins, serum IgG, circulating, serum antibodies, while, long-term immune memory, memory T, RBD-specific IgG, Cell, helper T cell, significantly, functional, determine, expressed, correlated, cytometric, declining, follicular, the SARS-CoV-2, 【제목키워드】 COVID-19, B cell memory, Rapid,