Related Experiment Videos
Immunogenic and protective properties of meningococcal serotype 2a protein in the hen-embryo model
Abstract:
The ability of serotype 2 outer membrane protein (SP-2) of Neisseria meningitidis strain M986 serogroup B, serotype 2a (B, 2a) to stimulate antibody formation in hens and to confer protection against meningococcal challenge to embryos from immunised hens was investigated. Hens, housed with roosters, were immunised with 100 micrograms of SP-2 once a week for 5 weeks to maintain consistent levels of serum antibody during the study. Antibodies in sera of hens, yolks and plasma of 13-day-old embryos reacted in enzyme-linked immunosorbent assays and immunodiffusion with outer membrane vesicles (OMV) from serotypes 2a, 2b and 2c and most of the other prototype group B strains of N. meningitidis. Cross-reactivity of hen sera with most OMV appeared after only one injection of SP-2. Embryos from immunised hens were protected against challenge with up to 10,000 LD50 doses of either the homologous strain M986 (B, 2a) or strain M1011 (B, 2a). Protection was also evident against strains 614 (W135, 2a), S5896 (Y, 2c) and 2241 (C, 2a), but not against strain 78704 (C, 2a) despite strong cross-reactivity of antibody with OMV of this strain. Embryos were only partially protected against strain 78069 (B, 2b) and were fully susceptible to strain 2996 (B, 2b). Some protection was also obtained against meningococcal strains M1080 (B, 1), M982 (B,9), S3032 (B, 12), 79001 (B, 12), 79694 (B, 15-related) but not strain 77252 (B, nontypable). These results suggest that proteins extracted from both serotype 2a and 2b meningococci would provide the broadest protection against infection with group B, serotype 2 meningococci and that antibody, presumably directed against common peptides in the major outer membrane proteins, can prevent infection by some other disease-associated serotypes of N. meningitidis.
Insights
Outer membrane protein SP-2 from Neisseria meningitidis serogroup B stimulated antibody production in hens. This antibody provided protection to chick embryos against various meningococcal serotypes, suggesting broad protective potential.
Area of Science:
- Immunology
- Microbiology
- Vaccine Development
Background:
- Neisseria meningitidis serogroup B is a significant cause of bacterial meningitis.
- Outer membrane proteins (OMPs) are key targets for developing vaccines against N. meningitidis.
- Serotype 2 is a common and important serotype within serogroup B.
Purpose of the Study:
- To investigate the immunogenicity of serotype 2 outer membrane protein (SP-2) from N. meningitidis strain M986 (B, 2a).
- To evaluate the protective efficacy of antibodies generated against SP-2 in a chick embryo model.
- To determine the cross-reactivity and protective spectrum of anti-SP-2 antibodies against different N. meningitidis strains.
Main Methods:
- Hens were immunized weekly for 5 weeks with 100 micrograms of SP-2.
- Antibody levels in hens, yolks, and embryo plasma were assessed using enzyme-linked immunosorbent assays (ELISA) and immunodiffusion.
- Chick embryos from immunized hens were challenged with live N. meningitidis strains to assess protection (LD50).
Main Results:
- Immunization with SP-2 successfully induced antibodies in hens, which were transferred to embryos.
- Anti-SP-2 antibodies showed cross-reactivity with outer membrane vesicles (OMVs) from multiple N. meningitidis serotypes (2a, 2b, 2c) and strains.
- Embryos from immunized hens were significantly protected against homologous strains (B, 2a) and showed partial to significant protection against other serogroups (W135, Y, C, B).
- Protection varied, with some strains (e.g., B, 2b and C, 2a) showing less protection despite antibody cross-reactivity.
Conclusions:
- Serotype 2 outer membrane protein (SP-2) is immunogenic and can elicit protective antibodies against Neisseria meningitidis.
- Antibodies against SP-2 offer broad protection against various serogroup B strains and some other serogroups, suggesting potential for a broader meningococcal vaccine.
- Targeting common peptides in major outer membrane proteins may confer protection against multiple N. meningitidis serotypes.