SARS-CoV-2 protein subunit vaccination of mice and rhesus macaques elicits potent and durable neutralizing antibody responses

The outbreak and spread of SARS-CoV-2 (severe acute respiratory syndrome-coronavirus-2) is a current global health emergency, and effective prophylactic vaccines are needed urgently. The spike glycoprotein of SARS-CoV-2 mediates entry into host cells, and thus is the target of neutralizing antibodies. Here, we show that adjuvanted protein immunization with soluble SARS-CoV-2 spike trimers, stabilized in prefusion conformation, results in potent antibody responses in mice and rhesus macaques, with neutralizing antibody titers exceeding those typically measured in SARS-CoV-2 seropositive humans by more than one order of magnitude. Neutralizing antibody responses were observed after a single dose, with exceptionally high titers achieved after boosting. A follow-up to monitor the waning of the neutralizing antibody responses in rhesus macaques demonstrated durable responses that were maintained at high and stable levels at least 4 months after boosting. These data support the development of adjuvanted SARS-CoV-2 prefusion-stabilized spike protein subunit vaccines. [Display omitted] Neutralizing antibodies are detectable after one adjuvanted spike protein immunizationBoosting yields higher neutralizing titers than observed in seropositive human donorsNeutralizing antibody titers remain high for at least 4 months after the last boostImmunization stimulates spike-specific memory B cells Mandolesi et al. show that immunization with adjuvanted prefusion-stabilized SARS-CoV-2 spike glycoprotein yields potent antibody responses in mice and macaques. Neutralizing antibodies are detectable after one immunization. Boosting results in exceptional potency, with neutralizing titers exceeding (>10-fold) those observed in seropositive humans and remaining high during a 4-month follow-up.