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In vitro induction of memory-driven responses against Neisseria meningitidis by priming with Neisseria lactamica
S Sánchez1, G Troncoso, M T Criado
1Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Abstract:
Natural immunity against Neisseria meningitidis is acquired during childhood and youth through successive colonizations by commensal Neisseria, carrier N. meningitidis, and other bacterial genera sharing cross-reactive antigens with the meningococci. We have analyzed in mice the ability of Neisseria lactamica strains to induce immunological memory so that, upon a later contact with N. meningitidis, quickly raise protective responses against antigens that show cross-reactivity with meningococcal surface proteins. Sera obtained from mice immunized with N. lactamica and boosted with N. meningitidis were able to kill meningococci, with bactericidal activities variable depending on the immunizing strains used in the assays. Different mixtures of those sera resulted in higher killing activities, which agrees with the idea that successive colonizations by N. lactamica enhance the anti-meningococcal response. The existence of such outer membrane cross-reactive antigens has to be kept in mind when using outer membrane vesicle (OMV)-based anti-meningococcal vaccines because their use can affect colonization by N. lactamica and other species, hampering the natural mechanisms of acquisition of immunity to the meningococci, and leaving its ecological niche free for colonization by undesirable microorganisms.
Insights
Natural immunity to Neisseria meningitidis develops through exposure to related bacteria. Studies show Neisseria lactamica can prime the immune system for better protection against meningococcal infections.
Area of Science:
- Microbiology
- Immunology
- Bacteriology
Background:
- Natural immunity against Neisseria meningitidis is acquired in childhood via colonization by commensal Neisseria, carrier N. meningitidis, and other bacteria with cross-reactive antigens.
- Understanding these natural immune acquisition mechanisms is crucial for developing effective meningococcal vaccines.
Purpose of the Study:
- To investigate the capacity of Neisseria lactamica strains to induce immunological memory in mice.
- To determine if this memory response enhances protection against subsequent Neisseria meningitidis challenge.
Main Methods:
- Mice were immunized with Neisseria lactamica strains and boosted with Neisseria meningitidis.
- Sera from immunized mice were tested for bactericidal activity against N. meningitidis.
- The effect of combining sera from different immunization groups was assessed.
Main Results:
- Sera from mice immunized with N. lactamica and boosted with N. meningitidis exhibited bactericidal activity against meningococci.
- Bactericidal activity varied depending on the specific N. lactamica strains used for immunization.
- Mixtures of sera showed enhanced killing activity, supporting the role of successive N. lactamica colonizations in boosting anti-meningococcal responses.
Conclusions:
- Neisseria lactamica can induce immunological memory that confers protection against Neisseria meningitidis.
- Outer membrane cross-reactive antigens are important considerations for outer membrane vesicle (OMV)-based meningococcal vaccines.
- OMV vaccines may interfere with natural immunity acquisition by impacting N. lactamica colonization, potentially creating space for pathogenic microorganisms.