An IgG and IgA -mediated humoral response directed against the N and S antigens is detected in the nasopharyngeal swabs of 2 severe COVID-19 patients but not in 2 pauci-symptomatic patients.
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Anti-N and anti-S serological responses differ according to the disease outcome, with reduced IgG response and enhanced anti-N IgA response in severe patient with fatal disease.
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Low serological response occurred in pauci-symptomatic patients, predominated by anti-S antibodies.
Abstract
Background
The systemic antibody responses to SARS-CoV-2 in COVID-19 patients has been extensively studied. However, less is known about the mucosal responses in the upper airways, the site of initial SARS-CoV-2 replication.
Methods
The IgG and IgA antibody responses were analysed in plasma and nasopharyngeal swabs from the first four confirmed COVID-19 patients in France. Two were pauci-symptomatic while two developed severe disease. We characterized their antibody profiles by using an in-house ELISA to detect antibodies directed against SARS-CoV-2 Nucleoprotein and Spike.
Results
Anti-N IgG and IgA antibodies were detected in the NPS of severe patients only. The levels of antibodies in the plasma markedly differed amongst the patients. The most distinctive features are a strong anti-N IgG response in the severe patient who recovered, and a high anti-N IgA response specifically detected in the fatal case of COVID-19.
Conclusions
Anti-N IgG and IgA antibodies are detected in NPS only for severe patients, with levels related to serological antibodies. The severe patients showed different antibody profiles in the plasma, notably regarding the IgA and IgG response to the N antigen, that may reflect different disease outcome. By contrast, pauci-symptomatic patients did not exhibit any mucosal antibodies in NSP, which is associated with a low or absent serological response against both N and S.
