Anti-Spike, anti-Nucleocapsid and neutralizing antibodies in SARS-CoV-2 inpatients and asymptomatic carriers

Summary Objective The objective of this study was to monitor the anti-SARS-CoV-2 antibody response in infected patients. Methods In order to assess the time of seroconversion, we used 151 samples from 30 COVID-19 inpatients and monitored the detection kinetics of anti-S1, anti-S2, anti-RBD and anti-N antibodies with in-house ELISAs. We also monitored the presence of neutralizing antibodies in these samples as well as 25 asymptomatic carrier samples using retroviral particles pseudotyped with the spike of the SARS-CoV-2. Results We observed that specific antibodies were detectable in all inpatients two weeks post-symptom onset. The detection of the SARS-CoV-2 Nucleocapsid and RBD was more sensitive than the detection of the S1 or S2 subunits. Neutralizing antibodies reached a plateau two weeks post-symptom onset and then declined in the majority of inpatients. Furthermore, neutralizing antibodies were undetectable in 56% of asymptomatic carriers. Conclusions Our results raise questions concerning the role played by neutralizing antibodies in COVID-19 cure and protection against secondary infection. They also suggest that induction of neutralizing antibodies is not the only strategy to adopt for the development of a vaccine. Finally, they imply that anti-SARS-CoV-2 neutralizing antibodies should be titrated to optimize convalescent plasma therapy. Highlights Specific antibodies are detectable in 100% COVID-19 inpatients two weeks post-symptom onset. The detection of the SARS-CoV-2 Nucleocapsid and Receptor Binding Domain is more sensitive than the detection of the S1 or S2 subunits. Neutralizing antibodies reach a plateau two weeks post-symptom onset and then decline in the majority of inpatients. Neutralizing antibodies are undetectable in the majority of asymptomatic carriers.