SARS-CoV-2 specific antibody and neutralization assays reveal the wide range of the humoral immune response to virus

Dogan, Mikail; Kozhaya, Lina; Placek, Lindsey; Gunter, Courtney; Yigit, Mesut; Hardy, Rachel; Plassmeyer, Matthew; Coatney, Paige; Lillard, Kimberleigh; Bukhari, Zaheer; Kleinberg, Michael; Hayes, Chelsea; Arditi, Moshe; Klapper, Ellen; Merin, Noah; Liang, Bruce Tsan-Tang; Gupta, Raavi; Alpan, Oral; Unutmaz, Derya

Development of antibody protection during SARS-CoV-2 infection is a pressing question for public health and for vaccine development. We developed highly sensitive SARS-CoV-2-specific antibody and neutralization assays. SARS-CoV-2 Spike protein or Nucleocapsid protein specific IgG antibodies at titers more than 1:100,000 were detectable in all PCR+ subjects (n = 115) and were absent in the negative controls. Other isotype antibodies (IgA, IgG1-4) were also detected. SARS-CoV-2 neutralization was determined in COVID-19 and convalescent plasma at up to 10,000-fold dilution, using Spike protein pseudotyped lentiviruses, which were also blocked by neutralizing antibodies (NAbs). Hospitalized patients had up to 3000-fold higher antibody and neutralization titers compared to outpatients or convalescent plasma donors. Interestingly, some COVID-19 patients also possessed NAbs against SARS-CoV Spike protein pseudovirus. Together these results demonstrate the high specificity and sensitivity of our assays, which may impact understanding the quality or duration of the antibody response during COVID-19 and in determining the effectiveness of potential vaccines.