Desenvolvimento de vacina intranasal nanoestruturada para a COVID-19

Abstract

COVID-19 is a human respiratory infectious disease caused by the Betacoronavirus SARS-CoV-2. Despite unprecedented efforts over the past three years to overcome the COVID-19 pandemic, the SARS-CoV-2 virus continues to cause unacceptable health losses. Vaccines are considered the most effective way to prevent infectious diseases, which has been reaffirmed for COVID-19. However, in the context of the virus's continued spread and the emergence of new variants, the development of new vaccine formulations is necessary to refine technology, minimize adverse effects, and improve safety and efficacy. Different technologies have been employed, such as inactivated whole-virus vaccines, recombinant protein subunits, and nucleic acid vaccines (DNA and mRNA), as well as viral vectors. All involve the parenteral administration of vaccines. In this work, we propose an alternative route, intranasal administration, with the aim of creating an immunological barrier at the virus's primary site of infection. Thus, the present study aimed to conjugate immunogenic epitopes of structural proteins from SARS-CoV-2 encapsulated in chitosan nanoparticles as an intranasal vaccine formulation. The monophosphoryl lipid A (MPLA) adjuvant was added to enhance the immunogenic effect of the formulation. A total of 82 peptides from SARS-CoV-2 structural proteins were identified as probable B-cell (n=37) and CD4+ T-cell (n=45) epitopes. Of these, 51 peptides were recognized by IgM, IgG, and IgA antibodies present in the serum of COVID-19 diagnosed patients, distributed as follows: 4 peptides (7.8%) were selected from the Membrane protein, 15 (29.4%) from the Nucleocapsid, and 32 (62.8%) from the Spike protein. Based on the intensity of antibody recognition, twenty-five peptides were selected for vaccine composition and evaluation of immunogenic potential in Balb/c mice through nasal administration, associated with nanostructured chitosan and monophosphoryl lipid A (MPLA) adjuvants. This vaccine configuration showed no hemolytic activity or cytotoxicity for the HEK-293 and MRC-5 human cell lines evaluated in vitro. Our results demonstrate that the intranasal peptide vaccine composition for SARS-CoV-2 induced a robust immune response in mice, with a production of specific IgG antibodies against SARS-CoV-2 Spike protein. Significant IFN-γ, IL-6 cytokines production, and low levels of TNF-α and IL-10 were also observed. We believe that the intranasal formulation outlined in this research is a new and promising candidate for a mucosal, needle-free primary immunization vaccine, as well as for revaccination protocols or conjugation with current vaccines, and it deserves further immunological investigation.