Plant-produced RBD and cocktail-based vaccine candidates are highly effective against SARS-CoV-2, independently of its emerging variants

SARS-CoV-2 is a novel and highly pathogenic coronavirus, which has caused an outbreak in Wuhan City, China, in 2019 and then spread rapidly throughout the world. Although several COVID-19 vaccines are currently available for mass immunization, they are less effective against emerging SARS-CoV-2 variants, especially the Omicron (B.1.1.529). Recently, we successfully produced receptor-binding domain (RBD) variants of spike (S) protein of SARC-CoV-2 and an antigen cocktail in Nicotiana benthamiana , which are highly produced in plants and elicited high-titer antibodies with potent neutralizing activity against SARS-CoV-2. In this study, we demonstrate that these protein-based vaccine candidates are highly effective against Delta and Omicron variants. These data support that plant produced RBD and cocktail-based antigens are most promising vaccine candidates and may protect against Delta and Omicron-mediated COVID-19. Based on the neutralization ability, plant produced RBD and cocktail-based vaccine candidates are highly effective against SARS-CoV-2, independently of its emerging variants.