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Age-associated differences in prevalence of group A streptococcal type-specific M antibodies in children

Preeti Jaggi1, James B Dale, Edna Chiang

  • 1Nationwide Children's Hospital, Ohio State University, 700 Children's Drive, Columbus, OH 43205, USA. Preeti.Jaggi@nationwidechildrens.org

European Journal of Pediatrics
|September 25, 2008
PubMed

Insights

Antibody levels against common Group A Streptococcus (GAS) M proteins increase with age in children. This suggests childhood infections lead to immunity against specific GAS strains, impacting pharyngitis epidemiology.

Area of Science:

  • * Microbiology and Immunology
  • * Molecular Epidemiology
  • * Pediatric Infectious Diseases

Background:

  • * Group A Streptococcus (GAS) pharyngitis is common in children, with specific M protein types (emm) dominating North American epidemiology.
  • * Previous research indicated a decrease in emm types 12 and 4 with increasing age, suggesting age-related immune responses.

Purpose of the Study:

  • * To investigate the hypothesis that age-associated antibody acquisition to GAS M protein N-terminal regions drives observed epidemiological trends.
  • * To quantify seroprevalence of antibodies against emm types 12, 1, 28, and 4 in healthy children across different age groups.

Main Methods:

  • * Enzyme-linked immunosorbent assays (ELISAs) were performed on sera from healthy children aged 3-18 years, divided into four age groups.
  • * Chemically synthesized peptides representing N-terminal type-specific M protein regions were used for antibody detection.
  • * ELISA data were correlated with opsonophagocytic assays for M1 GAS, and sera from infants served as negative controls.

Main Results:

  • * M12 showed the highest positivity percentage and progressive seropositivity with increasing age.
  • * Highest seroprevalence rates for emm types 1, 28, and 4 were observed in the 11-14-year-old age group.
  • * ELISA-detected antibodies against M1 correlated with opsonophagocytic activity, indicating functional immunity.

Conclusions:

  • * Antibody acquisition against GAS M proteins increases with age throughout childhood.
  • * This age-related seropositivity likely contributes to the changing epidemiology of GAS pharyngitis by conferring protection against specific strains.
  • * ELISA is a viable method for assessing functional antibodies against GAS M proteins.

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