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Immunogenicity of in vitro folded outer membrane protein PorA of Neisseria meningitidis
C Jansen1, B Kuipers, J van der Biezen
1Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
Abstract:
In vitro folded and the denatured form of PorA P1.6 from Neisseria meningitidis strain M990 were used for immunization studies in mice. Previously, the antigen was isolated from cytoplasmic inclusion bodies, folded and purified. Its immunogenicity without adjuvant appeared to be low. The addition of the adjuvant QuilA, but not of galE lipooligosaccharide, considerably enhanced the immunogenicity. Moreover, when immunized with folded PorA P1.6 plus QuilA, a clear switch towards the IgG2a subclass of antibodies and concomitantly, the appearance of serum bactericidal activity, which is believed to be important for protective immunity, was observed. Hence, a tool for preparing vaccines against serogroup B meningococci devoid of endotoxin is available.
Insights
Researchers developed an endotoxin-free vaccine against serogroup B meningococci. The addition of QuilA adjuvant significantly boosted the immunogenicity of the PorA P1.6 antigen, inducing protective antibodies.
Area of Science:
- Microbiology
- Immunology
- Vaccine Development
Background:
- PorA P1.6 is a key antigen from Neisseria meningitidis.
- Previous studies indicated low immunogenicity of purified PorA P1.6 without adjuvants.
Purpose of the Study:
- To evaluate the immunogenicity of in vitro folded and denatured PorA P1.6 from N. meningitidis strain M990 in mice.
- To assess the adjuvant effects of QuilA and galE lipooligosaccharide on PorA P1.6 immunogenicity.
Main Methods:
- In vitro refolding and purification of PorA P1.6 antigen.
- Immunization of mice with folded/denatured PorA P1.6, with or without QuilA or galE lipooligosaccharide.
- Analysis of antibody subclasses (IgG2a) and serum bactericidal activity.
Main Results:
- The immunogenicity of PorA P1.6 was low without adjuvant.
- QuilA significantly enhanced PorA P1.6 immunogenicity, unlike galE lipooligosaccharide.
- Immunization with folded PorA P1.6 plus QuilA induced IgG2a antibodies and serum bactericidal activity.
Conclusions:
- QuilA is an effective adjuvant for enhancing the immunogenicity of PorA P1.6.
- The developed approach provides a tool for creating endotoxin-free vaccines against serogroup B meningococci.
- The induction of serum bactericidal activity suggests potential for protective immunity.