Human immunogenicity studies on group A streptococcal C5a peptidase (SCPA) as a potential vaccine against group A streptococcal infections.
OBJECTIVE
Group A streptococcal C5a peptidase (SCPA) is a major virulence surface factor. Its highly conserved nature among all tested serotypes of group A streptococci (GAS) as well as animal protection studies make SCPA a prime vaccine candidate. The present study was undertaken to explore the human immunogenicity to SCPA using an indirect enzyme-linked immunosorbent assay.


METHODS
Children (n=72) who had signs and symptoms of acute pharyngitis and had GAS isolated from the throat at initial visit were included. Acute and convalescent sera were collected 4 weeks apart. ELISA was performed using recombinant SCPA peptide as antigen.


RESULTS
The mean convalescent anti-SCPA level was twice the level of mean acute anti-SCPA and the difference was statistically significant (P < 0.0001). There was a rise in convalescent anti-SCPA in all children aged 2-12 yr.


CONCLUSIONS
Our observations confirmed that SCPA was highly immunogenic in children infected with group A streptococcal pharyngitis. Further studies need to be done to characterize the immune response including antibody subclass.
Shet
Anita
A
Department of Pediatrics, World Health Organization Collaborating Center for Reference & Research on Streptococci, University of Minnesota Medical School, Minneapolis, MN 55455, USA. shetx002@umn.edu
Kaplan
Edward
E
Johnson
Dwight
D
Cleary
Patrick Paul
PP
D018829:Adhesins, Bacterial / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D010450:Endopeptidases / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D013290:Streptococcal Infections / Q000276:immunology / Q000517:prevention & control*; D013297:Streptococcus pyogenes / Q000201:enzymology*
D018829:Adhesins, Bacterial; D010450:Endopeptidases; C053088:C5a peptidase