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Published on: November 5, 2019
Immune responses of meningococcal B outer membrane vesicles in middle-aged mice
Gabriela Trzewikoswki de Lima1,2, Thais Sousa Rodrigues1, Amanda Izeli Portilho1,2
1Department of Immunology, Adolfo Lutz Institute, Av. Dr. Arnaldo 355, 11 floor, Sao Paulo, SP, Brazil.
Abstract:
The elderly are more likely to die when infected with Neisseria meningitidis. Aging is associated with immune system dysfunctions that impair responses to vaccines and infections. Therefore, immunization of middle-aged individuals could be beneficial. This study aims to evaluate the immunogenicity of N. meningitidis B outer membrane vesicles (OMVs) complexed to two different adjuvants. Middle-aged BALB/c and A/Sn mice were immunized and subsequent immune response was assessed by ELISA, immunoblotting and ELISpot. IgG levels were similar between the animals immunized with OMVs complexed to adjuvants. A total of 235 days after the last immunization only A/Sn mice presented higher IgG levels than those observed in the baseline, especially the group immunized with OMVs and aluminum hydroxide. The predominant IgG subclasses were IgG2a and IgG2b. Immunization with the three-dose regimen generated IgG antibodies that recognized a variety of antigens present in the homologous and heterologous meningococcal OMVs evaluated. There was an increase in the frequency of antigen-specific IFN-γ secreting splenocytes, after in vitro stimulation, in mice immunized with OMVs and adjuvants compared to the control group, almost 1 year after the last immunization. Both adjuvants showed similar performance. Immunization of middle-aged mice has generated a robust immune response and it appears to be advantageous.
Insights
Middle-aged mice showed a robust immune response to Neisseria meningitidis serogroup B outer membrane vesicles (OMVs) vaccines. Immunization generated long-lasting antibodies and T-cell responses, suggesting potential benefits for middle-aged individuals.
Area of Science:
- Immunology
- Vaccinology
- Microbiology
Background:
- Aging impairs immune responses to infections and vaccines, increasing mortality risk in elderly individuals infected with Neisseria meningitidis.
- Middle-aged populations may benefit from early immunization strategies to bolster immune defenses against meningococcal disease.
Purpose of the Study:
- To evaluate the immunogenicity of Neisseria meningitidis serogroup B outer membrane vesicles (OMVs) combined with two distinct adjuvants in middle-aged mice.
- To assess the durability of the immune response generated by this immunization strategy.
Main Methods:
- Middle-aged BALB/c and A/Sn mice were immunized with N. meningitidis B OMVs complexed to two different adjuvants.
- Immune responses were assessed using ELISA, immunoblotting, and ELISpot assays to measure IgG levels, subclasses, and antigen-specific IFN-γ secreting splenocytes.
Main Results:
- Immunization with OMVs and adjuvants generated robust and long-lasting IgG antibody levels, particularly in A/Sn mice, with IgG2a and IgG2b subclasses predominating.
- Antibodies recognized homologous and heterologous meningococcal OMVs, indicating broad antigen recognition.
- A significant increase in antigen-specific IFN-γ secreting splenocytes was observed, suggesting a durable cellular immune response almost one year post-immunization.
Conclusions:
- Immunization of middle-aged mice with N. meningitidis B OMVs and adjuvants elicits a strong and sustained immune response.
- The findings suggest that vaccinating middle-aged individuals could be a beneficial strategy to enhance protection against meningococcal infections.
