Distinct early IgA profile may determine severity of COVID-19 symptoms: an immunological case series

Christine Dahlke; Jasmin Heidepriem; Robin Kobbe; Rene Santer; Till Koch; Anahita Fathi; My L. Ly; Stefan Schmiedel; Peter H. Seeberger; Marylyn M. Addo; Felix F. Loeffler

The evolution of IgA and IgG antibodies, targeting SARS-CoV-2 peptides in patients #1 (Fig. 1c ) and #2 (Fig. 1d ) at different time points shows different dynamics: The more severe case (patient #1) showed few IgA-and IgG-reactive peptides (above control sample threshold) at d6, which considerably increased towards d22 after virus clearance. While reactive IgA peptides at d6 are only found in the ORF1ab polyprotein, the response becomes much broader during disease progression. In comparison, the mild case (patient #2) had a higher number of IgA-reactive SARS-CoV-2 peptides already at d3 post onset of symptoms and showed a decreasing number of reactive peptides from d3 to d24. At this early time point, we already detected defined IgA epitopes in the spike protein, while patient #1 developed IgA targeting spike epitopes only at d22. The trend of early SARS-CoV-2 IgA and IgG antibody response was also observed in the control patient #4 (moderate case, d4 and d12, Supporting Information Figure S1 & S2).