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Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination
Published on: September 25, 2014
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Serotype 15C Streptococcus pneumoniae resistant to classical complement deposition and agglutination by polyclonal
E J Kochis1, Y B Shaik-Dasthagirisaheb2, N Munarriz1
1Boston University Masters in Medical Sciences, Boston, MA, USA.
Vaccine
|October 5, 2024
Summary
Antibodies against Streptococcus pneumoniae 15B show limited cross-reactivity with 15C strains. This is evidenced by reduced complement deposition and agglutination, impacting their effectiveness against 15C infections.
Area of Science:
- Immunology
- Microbiology
- Vaccinology
Background:
- Streptococcus pneumoniae (SP) serotypes 15B and 15C are significant causes of invasive pneumococcal disease (IPD).
- A key difference between 15B and 15C is the O-acetylation of the 15B polysaccharide.
- The functional cross-reactivity of antibodies against SP15B with SP15C remains poorly understood.
Purpose of the Study:
- To compare the functional activity of polyclonal rabbit anti-capsular 15B sera against SP15B and SP15C isolates.
- To investigate complement activation and bacterial agglutination.
Main Methods:
- Flow cytometry was used to measure C3c and C4d deposition on SP15B and SP15C.
- Polyclonal rabbit anti-capsular 15B sera were incubated with SP serotypes and antibody-depleted complement.
- Bacterial agglutination was assessed by measuring forward and side scatter.
Main Results:
- Anti-15B sera induced high C4d and C3c deposition and agglutination on SP15B.
- Limited C4d and C3c deposition and agglutination were observed on SP15C.
- These differences indicate lower classical complement pathway activation by SP15C.
Conclusions:
- Anti-capsular 15B sera exhibit limited functional cross-reactivity with SP15C strains.
- This limited cross-reactivity is consistent with reduced opsonophagocytic killing of SP15C.
- Findings have implications for pneumococcal vaccine development and efficacy.
