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Protective immunity of microsphere-based mucosal vaccines against lethal intranasal challenge with Streptococcus
1Biomedical Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea.
Abstract:
Mucosal vaccination of capsular polysaccharide (PS) of Streptococcus pneumoniae and subsequent creation of the first line of immunological defense in mucosa were examined. Mucosal as well as systemic antibody responses to PS were evoked by peroral or intranasal immunization of BALB/c mice with PS-cholera toxin B subunit (CTB) conjugates entrapped in the alginate microspheres (AM). The bacterial colonization at the lung mucosa was most profoundly inhibited (<95%) by intranasal immunization with the naked conjugate (PS-CTB). The mice vaccinated orally with encapsulated conjugate [AM(PS-CTB)] showed significant reduction on the level of pneumococcal bacteremia (<99%). Eighty percent of the mice perorally immunized with AM (PS-CTB) were protected from lethal intranasal challenge with S. pneumoniae, whereas more than 60% of the mice in the other control groups died of infection. Our novel approach may prove to be important in the development of a mucosal vaccine that will provide protection of mucosal surfaces of host.
Insights
This study developed a novel mucosal vaccine using Streptococcus pneumoniae capsular polysaccharide (PS) conjugates. Intranasal immunization significantly inhibited bacterial lung colonization, offering protection against pneumococcal infection.
Area of Science:
- Immunology
- Vaccinology
- Microbiology
Background:
- Streptococcus pneumoniae causes significant respiratory infections.
- Developing effective mucosal vaccines remains a challenge.
- Capsular polysaccharide (PS) is a key target for pneumococcal vaccines.
Purpose of the Study:
- To evaluate the efficacy of a novel mucosal vaccine against Streptococcus pneumoniae.
- To investigate the induction of mucosal and systemic antibody responses.
- To assess protection against lethal pneumococcal challenge.
Main Methods:
- BALB/c mice were immunized with PS-cholera toxin B subunit (CTB) conjugates, encapsulated in alginate microspheres (AM) or as naked conjugates.
- Immunization routes included peroral and intranasal administration.
- Efficacy was measured by inhibition of bacterial colonization, reduction in bacteremia, and survival rates after lethal challenge.
Main Results:
- Intranasal immunization with naked PS-CTB conjugate profoundly inhibited lung mucosal bacterial colonization (<95%).
- Oral immunization with encapsulated conjugate [AM(PS-CTB)] significantly reduced pneumococcal bacteremia (<99%).
- Eighty percent of mice orally immunized with AM(PS-CTB) survived lethal S. pneumoniae challenge, compared to controls.
Conclusions:
- A novel mucosal vaccine approach using PS-CTB conjugates shows significant protective efficacy.
- Both intranasal and oral immunization routes can induce protective immune responses.
- This strategy holds promise for developing effective mucosal vaccines against pneumococcal infections.