Analysis of SARS-CoV-2 Antibodies in COVID-19 Convalescent Plasma using a Coronavirus Antigen Microarray

Rafael R. de Assis; Aarti Jain; Rie Nakajima; Algis Jasinskas; Jiin Felgner; Joshua M. Obiero; Oluwasanmi Adenaiye; Sheldon Tai; Filbert Hong; Philip Norris; Mars Stone; Graham Simmons; Anil Bagri; Martin Schreiber; Andreas Buser; Andreas Holbro; Manuel Battegay; Donald K. Milton; Huw Davies; Laurence M. Corash; Michael P. Busch; Philip L. Felgner; Saahir Khan

To determine the antibody profile of SARS-CoV-2 infection, the differential reactivity to these antigens was evaluated for SARS-CoV-2 convalescent plasma from PCR-positive individuals (positive group) and sera collected prior to the COVID-19 pandemic from naïve individuals (negative group) as shown in Figure 1 . The positive group demonstrates high IgG reactivity to SARS-CoV-2 NP, S2, and S1+S2 antigens and moderate IgG reactivity to SARS-CoV-2 S1 and RBD antigens, while the negative group demonstrates low IgG cross-reactivity to SARS-CoV-2 S1+S2 and no cross-reactivity to other SARS-CoV-2 antigens (Figure 2 ). The positive group also demonstrates high IgG cross-reactivity with SARS-CoV NP and MERS-CoV S2 and S1+S2 antigens, while the negative group demonstrates low cross-reactivity with MERS-CoV S1+S2 and no cross-reactivity with other SARS-CoV and MERS-CoV antigens. The two groups do not differ significantly in reactivity to common cold coronaviruses and other seasonally circulating respiratory viruses. Similar trends are observed for IgA but with lower reactivity overall (Figure 3 ). The positive group again demonstrates high IgA reactivity to SARS-CoV-2 NP, S2, and S1+S2 and moderate IgA reactivity to SARS-CoV-2 S1 with high IgA cross-reactivity to SARS-CoV NP, while the negative group demonstrates low IgA cross-reactivity to all SARS-CoV-2, SARS-CoV, and MERS-CoV antigens.