Characterization of neutralizing versus binding antibodies and memory B cells in COVID-19 recovered individuals from India

Nayak, Kaustuv; Gottimukkala, Kamalvishnu; Kumar, Sanjeev; Reddy, Elluri Seetharami; Edara, Venkata Viswanadh; Kauffman, Robert; Floyd, Katharine; Mantus, Grace; Savargaonkar, Deepali; Goel, Pawan Kumar; Arora, Satyam; Rahi, Manju; Davis, Carl W.; Linderman, Susanne; Wrammert, Jens; Suthar, Mehul S.; Ahmed, Rafi; Sharma, Amit; Murali-Krishna, Kaja; Chandele, Anmol

India is one of the most affected countries by COVID-19 pandemic; but little is understood regarding immune responses to SARS-CoV-2 in this region. Herein we examined SARS-CoV-2 neutralizing antibodies, IgG, IgM, IgA and memory B cells in COVID-19 recovered individual from India. While a vast majority of COVID-19 recovered individuals showed SARS-CoV-2 RBD-specific IgG, IgA and IgM antibodies (38/42, 90.47%; 21/42, 50%, 33/42, 78.57% respectively), only half of them had appreciable neutralizing antibody titers. RBD-specific IgG, but not IgA or IgM titers, correlated with neutralizing antibody titers and RBD-specific memory B cell frequencies. These findings have timely significance for identifying potential donors for plasma therapy using RBD-specific IgG assays as surrogate measurement for neutralizing antibodies in India. Further, this study provides useful information needed for designing large-scale studies towards understanding of inter-individual variation in immune memory to SARS CoV-2 natural infection for future vaccine evaluation and implementation efforts.