Bioengineered polyester beads co-displaying protein and carbohydrate-based antigens induce protective immunity against bacterial infection

Abstract The efficacy of protein and carbohydrate antigens as vaccines can be improved via particulate delivery strategies. Here, protein and carbohydrate antigens used in formulations of vaccines against Neisseria menigitidis were displayed on in vivo assembled polyester beads using a combined bioengineering and conjugation approach. An endotoxin-free mutant of Escherichia coli was engineered to produce translational fusions of antigens (Neisseria adhesin A (NadA) and factor H binding protein (fHbp) derived from serogroup B) to the polyhydroxybutyrate synthase (PhaC), in order to intracellularly assemble polyester beads displaying the respective antigens. Purified beads displaying NadA showed enhanced immunogenicity compared to soluble NadA. Both soluble and particulate NadA elicited functional antibodies with bactericidal activity associated with protective immunity. To expand the antigen repertoire and to design a more broadly protective vaccine, NadA-PhaC beads were additionally conjugated to the capsular polysaccharide from serogroup C. Co-delivery of surface displayed NadA and the capsular polysaccharide induced a strong and specific Th1/Th17 mediated immune response associated with functional bactericidal antibodies. Our findings provide the foundation for the design of multivalent antigen-coated polyester beads as suitable carriers for protein and polysaccharide antigens in order to induce protective immunity

Comparative Immune Response after Vaccination with SOBERANA^® 02 and SOBERANA^® plus Heterologous Scheme and Natural Infection in Young Children

(1) Background: In children, SARS-CoV-2 infection is mostly accompanied by mild COVID-19 symptoms. However, multisystem inflammatory syndrome (MIS-C) and long-term sequelae are often severe complications. Therefore, the protection of the pediatric population against SARS-CoV-2 with effective vaccines is particularly important. Here, we compare the humoral and cellular immune responses elicited in children (n = 15, aged 5–11 years) vaccinated with the RBD-based vaccines SOBERANA® 02 and SOBERANA® Plus combined in a heterologous scheme with those from children (n = 10, aged 4–11 years) who recovered from mild symptomatic COVID-19. (2) Methods: Blood samples were taken 14 days after the last dose for vaccinated children and 45–60 days after the infection diagnosis for COVID-19 recovered children. Anti-RBD IgG and ACE2-RBD inhibition were assessed by ELISA; IgA, cytokines, and cytotoxic-related proteins were determined by multiplex assays. Total B and T cell subpopulations and IFN-γ release were measured by multiparametric flow cytometry using a large panel of antibodies after in vitro stimulation with S1 peptides. (3) Results: Significant higher levels of specific anti-RBD IgG and IgA and ACE2-RBD inhibition capacity were found in vaccinated children in comparison to COVID-19 recovered children. Th1-like and Th2-like CD4+ T cells were also significantly higher in vaccinated subjects. IFN-γ secretion was higher in central memory CD4+ T cells of COVID-19 recovered children, but no differences between both groups were found in the CD4+ and CD8+ T cell effector, terminal effector, and naïve T cell subpopulations. In contrast to low levels of IL-4, high levels of IL-2, IL-6, IFN-γ, and IL-10 suggest a predominant Th1 cell polarization. Cytotoxic-related proteins granzyme A and B, perforin, and granulin were also found in the supernatant after S1 stimulation in both vaccinated and recovered children. (4) Conclusions: Vaccination with the heterologous scheme of SOBERANA® 02/SOBERANA® Plus induces a stronger antibody and cellular immune response compared to natural infections in young children

Open-label phase I/II clinical trial of SARS-CoV-2 receptor binding domain-tetanus toxoid conjugate vaccine (FINLAY-FR-2) in combination with receptor binding domain-protein vaccine (FINLAY-FR-1A) in children

Objectives: To evaluate a heterologous vaccination scheme in children 3-18 years old (y/o) combining two SARS-CoV-2r- receptor binding domain (RBD)protein vaccines. Methods: A phase I/II open-label, adaptive, and multicenter trial evaluated the safety and immunogenicity of two doses of FINLAY-FR-2 (subsequently called SOBERANA 02) and the third heterologous dose of FINLAY-FR-1A (subsequently called SOBERANA Plus) in 350 children 3-18 y/o in Havana Cuba. Primary outcomes were safety (phase I) and safety/immunogenicity (phase II) measured by anti-RBD immunoglobulin (Ig)G enzyme-linked immunoassay (ELISA), molecular and live-virus neutralization titers, and specific T-cells response. A comparison with adult immunogenicity and predictions of efficacy were made based on immunological results. Results: Local pain was the unique adverse event with frequency >10%, and none was serious neither severe. Two doses of FINLAY-FR-2 elicited a humoral immune response similar to natural infection; the third dose with FINLAY-FR-1A increased the response in all children, similar to that achieved in vaccinated young adults. The geometric mean (GMT) neutralizing titer was 173.8 (95% confidence interval [CI] 131.7; 229.5) vs Alpha, 142 (95% CI 101.3; 198.9) vs Delta, 24.8 (95% CI 16.8; 36.6) vs Beta and 99.2 (95% CI 67.8; 145.4) vs Omicron. Conclusion: The heterologous scheme was safe and immunogenic in children 3-18 y/o. Trial registry: https://rpcec.sld.cu/trials/RPCEC0000037