Abstract
Background: Whereas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibody tests are increasingly being used to estimate the prevalence of SARS-CoV-2 infection, the determinants of these antibody responses remain unclear.
Objectives: Our aim was to evaluate systemic and mucosal antibody responses toward SARS-CoV-2 in mild versus severe coronavirus disease 2019 (COVID-19) cases.
Methods: Using immunoassays specific for SARS-CoV-2 spike proteins, we determined SARS-CoV-2-specific IgA and IgG in sera and mucosal fluids of 2 cohorts, including SARS-CoV-2 PCR-positive patients (n = 64) and PCR-positive and PCR-negtive health care workers (n = 109).
Results: SARS-CoV-2-specific serum IgA titers in patients with mild COVID-19 were often transiently positive, whereas serum IgG titers remained negative or became positive 12 to 14 days after symptom onset. Conversely, patients with severe COVID-19 showed a highly significant increase of SARS-CoV-2-specific serum IgA and IgG titers after symptom onset. Very high titers of SARS-CoV-2-specific serum IgA were correlated with severe acute respiratory distress syndrome. Interestingly, some health care workers with negative SARS-CoV-2-specific serum antibody titers showed SARS-CoV-2-specific IgA in mucosal fluids with virus-neutralizing capacity in some cases. SARS-CoV-2-specific IgA titers in nasal fluids were inversely correlated with age.
Conclusions: Systemic antibody production against SARS-CoV-2 develops mainly in patients with severe COVID-19, with very high IgA titers seen in patients with severe acute respiratory distress syndrome, whereas mild disease may be associated with transient production of SARS-CoV-2-specific antibodies but may stimulate mucosal SARS-CoV-2-specific IgA secretion.
Keywords: COVID-19; COVID-19 seroprevalence; COVID-19 severity; SARS-CoV-2; SARS-CoV-2–specific IgA; SARS-CoV-2–specific IgG; SARS-CoV-2–specific antibodies; humoral immune response; mucosal immune response.
【저자키워드】 COVID-19, SARS-CoV-2, COVID-19 severity, humoral immune response, COVID-19 seroprevalence, SARS-CoV-2–specific IgA, SARS-CoV-2–specific IgG, SARS-CoV-2–specific antibodies, mucosal immune response., 【초록키워드】 IgG, coronavirus, severe COVID-19, SARS-COV-2 infection, Antibody Response, immune, Prevalence, immunoassay, serum, IgA, sera, Patient, Health care worker, Mild, age, serum antibody, Antibody test, disease, acute respiratory distress, mucosal, IgG titer, humoral, antibody production, systemic, determinant, symptom onset, acute respiratory syndrome, SARS-CoV-2-specific antibody, severe coronavirus disease, significant increase, PCR-positive, secretion, syndrome, SARS-CoV-2 spike proteins, cohorts, serum IgG, positive, nasal fluid, mucosal immune, develop, evaluate, remained, correlated, virus-neutralizing, stimulate, increasingly, IgA titer, PCR-positive patient, 【제목키워드】 severe COVID-19, Antibody Response, Mild, mucosal, systemic,