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Antibody responses to serogroup B meningococcal outer membrane antigens after vaccination and infection
E Rosenqvist1, S Harthug, L O Frøholm
1National Institute of Public Health, Oslo, Norway.
Abstract:
Antibody responses of adult volunteers given a vaccine containing meningococcal capsular polysaccharides (serogroups A, C, Y, and W-135) noncovalently complexed with serotype 2b:P1.2 and 15:P1.16 outer membrane proteins have been studied. Sera were analyzed by enzyme-linked immunosorbent assay methods for immunoglobulin G (IgG), IgM, and IgA antibodies and for bactericidal activities against the homologous strains. The vaccination was performed as a double-blind experiment with 47 volunteers, of whom 23 received the protein-polysaccharide vaccine and 24 received the control preparation containing the polysaccharides only. Ten additional persons volunteered for the protein-polysaccharide vaccine. Before vaccination, carriers of meningococci had significantly higher levels of specific IgG and IgA and also higher bactericidal activities than noncarriers. At 2 weeks postvaccination we found significant IgG and bactericidal antibody responses against both the 2b:P1.2 and 15:P1.16 strains in about 70% of the protein-polysaccharide vaccinees. The immune response induced by disease was compared with that induced by vaccination by analyzing paired sera from 13 survivors of serogroup B serotype 15 meningococcal disease. We found that the mean specific IgG level in acute-phase sera was lower than average in prevaccination sera from the vaccinees but similar to that of healthy noncarriers before vaccination. The convalescent-phase sera showed IgG responses similar to those of the vaccinees, but the IgM response to disease was significantly higher than after vaccination. The immune response to disease caused by serogroup B serotype 15 meningococci was found by enzyme-linked immunosorbent assay analysis to be about the same with outer-membrane antigens from a serotype 2b strain as it was with antigens from a serotype 15 strain.
Insights
This study shows that a meningococcal vaccine combining polysaccharides and outer membrane proteins elicits significant antibody and bactericidal responses. Disease-induced immunity, particularly IgM, was stronger than vaccine-induced immunity.
Area of Science:
- Immunology
- Vaccinology
- Microbiology
Background:
- Meningococcal disease remains a public health concern, necessitating effective vaccines.
- Understanding immune responses to vaccination and natural infection is crucial for vaccine development.
- Outer membrane proteins and polysaccharides are key components in meningococcal vaccines.
Purpose of the Study:
- To evaluate antibody and bactericidal responses in volunteers receiving a novel meningococcal vaccine.
- To compare immune responses induced by vaccination versus natural infection with serogroup B meningococci.
- To assess the role of meningococcal outer membrane proteins and polysaccharides in immune response.
Main Methods:
- Double-blind, placebo-controlled trial involving protein-polysaccharide vaccine and polysaccharide-only control.
- Enzyme-linked immunosorbent assay (ELISA) to measure immunoglobulin G (IgG), IgM, and IgA antibody levels.
- Bactericidal assays to determine functional antibody activity against homologous meningococcal strains.
- Analysis of paired sera from survivors of serogroup B meningococcal disease.
Main Results:
- The protein-polysaccharide vaccine induced significant IgG and bactericidal antibody responses in approximately 70% of vaccinees.
- Pre-vaccination carriers of meningococci had higher baseline levels of specific IgG, IgA, and bactericidal activity.
- While IgG responses were similar, IgM responses to natural disease were significantly higher than those induced by vaccination.
Conclusions:
- The studied meningococcal vaccine effectively elicits protective immune responses.
- Natural infection with serogroup B meningococci induces a stronger IgM response compared to vaccination.
- Outer membrane antigens from serotype 2b and 15 strains elicit comparable immune responses to serogroup B meningococcal disease.