An enveloped virus-like particle vaccine expressing a stabilized prefusion form of the SARS-CoV-2 spike protein elicits highly potent immunity

Fluckiger, Anne-Catherine; Ontsouka, Barthelemy; Bozic, Jasminka; Diress, Abebaw; Ahmed, Tanvir; Berthoud, Tamara; Tran, Anh; Duque, Diane; Liao, Mingmin; McCluskie, Michael; Diaz-Mitoma, Francisco; Anderson, David E.; Soare, Catalina

We evaluated enveloped virus-like particles (eVLPs) expressing various forms of the Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spike protein and several adjuvants in an effort to identify a highly potent Coronavirus disease 2019 (COVID-19) vaccine candidate. eVLPs expressing a modified prefusion form of SARS-CoV-2 spike protein were selected as they induced high antibody binding titers and neutralizing activity after a single injection in mice. Formulation of SARS-CoV-2 S eVLPs with aluminum phosphate resulted in balanced induction of IgG2 and IgG1 isotypes and antibody binding and neutralization titers were undiminished for more than 3 months after a single immunization. A single dose of this candidate, named VBI-2902a, protected Syrian golden hamsters from challenge with SARS-CoV-2 and supports the on-going clinical evaluation of VBI-2902a as a highly potent vaccine against COVID-19.