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Antibodies against pneumococcal C-polysaccharide are not protective
S V Nielsen1, U B Sørensen, J Henrichsen
1World Health Organization Collaborating Centre for Reference and Research on Pneumococci, Statens Seruminstitut, Copenhagen, Denmark.
Microbial Pathogenesis
|April 1, 1993
Summary
Antibodies targeting the C-polysaccharide (C-Ps) of Streptococcus pneumoniae did not prevent infection in mice. However, type-specific antibodies and those targeting phosphorylcholine (PC) showed protection in certain cases.
Area of Science:
- Immunology
- Microbiology
- Vaccine Development
Background:
- Streptococcus pneumoniae causes significant morbidity and mortality worldwide.
- The capsular polysaccharide (C-Ps) is a key target for vaccines and therapeutics.
- Understanding antibody efficacy against C-Ps is crucial for developing effective treatments.
Purpose of the Study:
- To evaluate the protective capacity of antibodies against C-polysaccharide (C-Ps) in a mouse model of pneumococcal infection.
- To determine if antibodies targeting specific components of C-Ps, like phosphorylcholine (PC), offer protection.
Main Methods:
- Passive immunization of outbred mice with monoclonal and polyclonal antibodies against C-Ps.
- Challenge with different serotypes of Streptococcus pneumoniae (types 6A, 14, and 27).
- Assessment of protection based on survival rates and bacterial load.
Main Results:
- Monoclonal and polyclonal antibodies against C-Ps backbone or specific for C-Ps did not protect against types 6A and 14 pneumococcal infection.
- A monoclonal antibody specific for phosphorylcholine (PC) demonstrated protection against type 27 pneumococcus, which contains PC.
- Type-specific antibodies (monoclonal and polyclonal) provided high protection against homologous pneumococcal types.
Conclusions:
- Passive immunization with antibodies to C-Ps does not confer species-specific protection against intraperitoneal Streptococcus pneumoniae infection in mice.
- Antibody efficacy is dependent on the specific pneumococcal serotype and the targeted antigen (e.g., PC).
- Type-specific antibodies are essential for effective protection against homologous pneumococcal strains.