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Immune response of neonates to pneumococcal polysaccharide-protein conjugate
Insights
Pneumococcal polysaccharide-protein conjugates significantly boost antibody production in mice compared to polysaccharides alone. Maternal immunization and booster doses in young mice enhance immune response, but secondary immunization can suppress it.
Area of Science:
- Immunology
- Vaccinology
- Microbial Pathogenesis
Background:
- Pneumococcal polysaccharides are key targets for vaccines.
- Understanding immune responses to different pneumococcal antigen formulations is crucial for vaccine development.
Purpose of the Study:
- To evaluate the immunogenicity of pneumococcal polysaccharides (PSs) and PS-protein conjugates in mice.
- To investigate the impact of maternal immunization and secondary immunization on immune responses.
Main Methods:
- Mice (adult and young) were immunized with pneumococcal 6A and 19F PSs, and 19F PS conjugated to proteins (HIgG, R61 polypeptide, BSA).
- Antibody titers (IgM, IgG2) were measured.
- Maternal immunization and secondary immunization protocols were employed.
Main Results:
- 19F PS-protein conjugates induced significantly higher IgM and IgG2 antibody titers than 19F PS alone.
- Maternal immunization with 19F PS-HIgG conjugate resulted in a low offspring response, but a booster dose improved it.
- Young mice exposed to a 14-valent vaccine during gestation showed enhanced responses to 6A and 19F PSs.
- Secondary immunization with 19F PS or conjugate suppressed immune response.
Conclusions:
- Pneumococcal polysaccharide-protein conjugates are more immunogenic than unconjugated polysaccharides.
- Maternal immunization strategies can be optimized with booster doses for enhanced offspring immunity.
- Timing of immunization is critical; secondary immunization shortly after primary can be detrimental.
Abstract:
Immune responses were studied in adult and young mice exposed to pneumococcal 6A and 19F polysaccharides (PSs), as well as 19F PS conjugated to proteins, e.g. human immunoglobulin G (HIgG), pneumococcal R61 cell wall polypeptide, and bovine serum albumin (BSA). Significantly higher IgM and IgG2 antibody titres were induced in mice receiving 19F PS-protein conjugates than in the control group receiving 19F PS alone. Maternal immunization with 19F PS-HIgG conjugate elicited a low immune response in the offspring. However, when young mice from immunized mothers were given and additional dose of polysaccharide-protein conjugate, they gave an antibody response greater than that of mice not given additional immunogen. Similarly, young mice exposed to 14-valent pneumococcal vaccine during gestation produced higher antibody response to 6A and 19F PSs. Secondary immunization of 19F PS or PS-protein conjugate at 1 or 2 weeks after primary immunization did not enhance antibody formation but rather suppressed the immune response to that polysaccharide.