PRECLINICAL IMMUNOGENICITY STUDIES OF A RECOMBINANT VACCINE FORMULATION AGAINST COVID-19

AGOSTINA DEMARÍA; LORENA CORIA; CELESTE PUEBLAS CASTRO; LAURA BRUNO; ELIANA CASTRO; LUCAS SAPOSNIK; MAYRA RÍOS MEDRANO; VALERIA KRUM; IGNACIO DREHE; MARIANA LI CAUSI; JOHANNA SIDABRA; JONATHAN BAQUÉ; CRISTIAN PAYES; BRENDA HEINRICH; ANALÍA DE NICHILO; FRANCISCO ZURVARRA; DIEGO ALVAREZ; KARINA PASQUEVICH; JULIANA CASSATARO

Congreso; Reunión Anual de sociedades de Biociencias; 2022

In this work, we studied the immunogenicity of vaccine formulations based on the receptor binding domain (RBD) of the spike protein from SARS-CoV-2. BALB/c mice were immunized by intramuscular route with two vaccine formulations that contained different antigen (Ag) doses. Induction of Ag-specific IgG antibody titers were determined in sera of immunized animals. Results showed that both formulations induced high but similar anti-RBD IgG titers. Evaluation of Ag-specific IgG subclasses showed that both vaccine formulations induced higher titers of IgG1 than IgG2a. Interestingly, independently of the Ag dose specific IgG antibody titers against RBD remained elevated until 253 days post prime vaccination. Virus neutralization capacity of antibodies induced by these vaccines was evaluated in a live virus neutralization assay. Results indicate that both vaccine formulations elicited antibodies that have neutralizing activity against ancestral, gamma, alpha, lambda and delta SARS-CoV-2 variants. Finally, to determine T-cell-mediated immune responses, splenocytes from immunized mice were stimulated in vitro with complete medium or the Ag and cytokine levels were measured in supernatants by ELISA. Splenocytes from all vaccinated mice induced significant levels of IFN-γ and IL-5 upon antigen stimulation (p