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Immune response to group A streptococcal C5a peptidase in children: implications for vaccine development
Anita Shet1, Edward L Kaplan, Dwight R Johnson
1Department of Pediatrics, World Health Organization Collaborating Center for Reference and Research on Streptococci, Minneapolis, USA. shetx002@umn.edu
Insights
Group A Streptococcus C5a peptidase (SCPA) is a key virulence factor. Human immune responses to SCPA are strong and consistent, supporting its potential as a vaccine target for preventing GAS disease.
Area of Science:
- Microbiology
- Immunology
- Vaccinology
Background:
- Group A Streptococcus (GAS) causes various infections, with SCPA identified as a major surface virulence factor.
- SCPA aids in the establishment of local GAS infections.
Purpose of the Study:
- To measure the human immune response to SCPA.
- To evaluate SCPA as a potential vaccine candidate against GAS disease.
Main Methods:
- Indirect enzyme-linked immunosorbent assay (ELISA) was used to measure immune response.
- Paired acute and convalescent serum samples from children with GAS pharyngitis were analyzed.
- Western blot analysis confirmed SCPA expression across different GAS M types.
Main Results:
- A robust human immune response to SCPA was observed.
- The immune response to SCPA was consistent across different GAS M types and patient ages.
- SCPA immunogenicity correlated with established markers like anti-streptolysin O and anti-DNase B.
- All tested GAS M types expressed SCPA.
Conclusions:
- SCPA is immunogenic in humans.
- Its conserved nature, role in virulence, and demonstrated immunogenicity make SCPA a promising vaccine candidate for preventing GAS infections.
Abstract:
The group A streptococcal C5a peptidase (SCPA) is a major surface virulence protein that facilitates the establishment of local infection by group A streptococci (GAS). We measured the human immune response to SCPA, using a standardized indirect enzyme-linked immunosorbent assay. Paired acute and convalescent serum samples from children with GAS-associated pharyngitis were assayed, and a strong immune response to SCPA was demonstrated that was independent of the infecting M type and the age of the patient. Western blot analysis of bacterial extracts revealed that all tested M types expressed SCPA. The immune response to SCPA correlated with the anti-streptolysin O and anti-DNase B responses. These data confirm the immunogenicity of SCPA in humans. Previous knowledge of SPCA's role in virulence, its highly conserved nature, and the results of mouse protection studies make SCPA an ideal vaccine candidate for the prevention of GAS disease.