Antibody isotype profiling before and after administration of ARVAC: a protein subunit vaccine booster against SARS-CoV-2

CLARA G. FASCETTO CASSERO; FEDERICO PÁEZ CÓRDOBA; BRUNO LAURA; CORIA, LORENA; CEBALLOS, ANA; RODRIGUEZ, JUAN MANUEL; DEMARÍA, AGOSTINA; PRADO, LINEIA; CASTRO, CELESTE PUEBLAS; DE OCA, FEDERICO MONTES; VEGA, JULIO C.; FLO, JUAN M.; JORGE CASSARÁ; CASSATARO JULIANA; PASQUEVICH KARINA

Buenos Aires

Congreso; 14th Latin American and Caribbean Congress of Immunology (ALACI 2024); 2024

ALACI

: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing the coronavirus disease 2019 (COVID-19) pandemic has continued to evolve rapidly. While different developed vaccines have shown clinical efficacy against ancestral SARS-CoV-2, waning immunity and immune escape variants led the need of boosters and variant adapted vaccines. Among these the recombinant subunit ARVAC vaccine has shown robust neutralizing antibody (NAb) responses against several SARS-CoV-2 variants. Although NAbs are considered an important correlate of protection against SARS-CoV-2 the role of other fragment crystallizable (Fc) functional antibodies in vaccine protection has received less attention. Recently, repeated SARS-CoV-2 mRNA vaccination has been linked to IgG4 skewing. In this work, antigen-specific IgG1, IgG2, IgG3, and IgG4 were evaluated in clinical samples of voluntaries that received one or two booster doses of ARVAC. Analysis of antibody isotypes previous to ARVAC booster showed, in agreement with recently published studies, that repeated mRNA SARS-CoV-2 vaccination was associated with high levels of RBD-specific IgG4, whereas these antibodies were low or undetectable in volunteers with one or none previous mRNA doses. The four Ag specific antibody isotypes were increased upon ARVAC booster, being in general, the IgG1 isotype the most predominant. Nevertheless, the proportion of IgG4 to IgG1 was similar before and after receiving the booster. These results suggest that one or two booster doses of ARVAC do not induce a class switch toward noninflammatory, RBD-specific IgG4 antibodies as it was shown after repeated SARS-CoV-2 mRNA vaccination.