Functional neutralizing and bactericidal antibody responses induced by dual-target immunization with SARS-CoV-2 RBD and Neisseria meningitidis antigens in mice.

Vaccination can elicit functional antibodies to reduce the burden of infectious diseases, such as neutralizing antibodies (nAbs) to control COVID-19, and bactericidal antibodies to prevent meningococcal disease. BALB/c mice were immunized with the receptor binding domain (RBD) from SARS-CoV-2, mixed with outer membrane vesicles (OMVs) from N. meningitidis and Aluminum hydroxide, resulting in a simultaneous immune response to SARS-CoV-2 and meningococci, and IgG transference to the offspring, as published in a previous article. In this brief communication, antibodies' function was assessed by cytopathic effect-based virus neutralization test, serum bactericidal assay and immunoblotting. Mice immunized with RBD + OMV + AH presented high nAbs and bactericidal titers, which recognized Neisseria antigens from 58 to 80 kDa. IgG detected on the offspring followed the same pattern of mothers. The results suggest that the immunization approach induced functional antibodies to both pathogens.