Vaccination with outer membrane vesicles from Neisseria Meningitidis and SBa15, SBa16 mesoporous silica associated with SARS-CoV-2 induces protective humoral and cellular response against COVID-19 in mice

The global impact of the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic in 2019-2020 has led to significant changes in worldwide vaccination and immune prophylactic approaches. In this study, our research delves into a new immunization strategy that does not involve the use of additional adjuvants or preservatives, focusing on the effects of virus fusion with a bacterial nanostructure. The experimental procedures outlined in this paper involved the cultivation of SARS-CoV-2, the production, extraction, and nanocharacterization of outer membrane vesicles (OMV) from Neisseria meningitidis, immunization of mice with two doses of OMV combined with SARS-CoV-2, and the use of mesoporous silica SBa15 and SBa16 adsorbed to the same virus. The immune response was assessed through an indirect elisa method, analysis of cytokine expression profiles, and seroneutralization of the SARS-CoV-2 strain. The characterizations of associated OMV - SARS-CoV-2 and adsorption SBa15 and SBa16 were performed using Nanosight Tracking Analysis (NTA), which showed a high density of particles in the formulation. mice were then immunized, resulting in an immune response that produced high levels of neutralizing antibodies in IgG and IgG1 mouse immunoglobulins. In addition, expressions of IL-2, IL-4, and IL-23 in spleen cells were reinforced after the vaccination process. The comparative study of these three vaccine formulations has shown that the development of new vaccines for SARS-CoV-2 should take into consideration the production of neutralizing antibodies and the maintenance of immunological memory.