Dual-Adjuvanted Meningococcal OMVs C Vaccine: Functionality and Cross-Reactive IgG in BALB/c Mice 2267478

Abstract Introduction Meningococcal disease is a major public health issue in Brazil and worldwide, especially among children and young adults. Broad-coverage vaccines are lacking in Brazil, and the high genetic variability of Neisseria meningitidis strains limits the efficacy of current vaccines. This study evaluated the immunogenicity of outer membrane vesicles (OMVs) from serogroup C combined with Cholera Toxin Subunit B and Alum adjuvants. Methods BALB/c mice received three subcutaneous doses on days 10, 40, and 55. IgG and subclasses (1, 2a, 2b and 3) were analyzed by ELISA; IgG functionality by ELISA-avidity. Immunoblot tested IgG recognition of OMVs from homologous strains, and Dot-blot evaluated cross-reactivity against heterologous strains circulating in Brazil. Results IgG responses increased after the second dose (p < 0.001) and further after the third (p < 0.0001). High-avidity IgG was detected after the second (60.31 ± 16.31) and third doses (76.35 ± 14). Predominant IgG1 indicated a Th2-skewed profile. The third dose enhanced IgG diversity and specificity, with recognition of antigens between 25—58 kDa and 100—190 kDa from the homologous strain. Cross-reactive IgG recognized epidemiologically relevant heterologous strains from serogroups B, C, and W. Conclusion The OMV/C with CTB and Alum formulation induces a robust and functional immune response, supporting its potential as a candidate for broader-spectrum vaccines against diverse Brazilian Neisseria meningitidis strains. Funding Source CAPES — Coordination for the Improvement of Higher Education Personnel Topic Categories Vaccines and Immunotherapy (VAC)