Distribution of streptococcal inhibitor of complement variants in pharyngitis and invasive isolates in an epidemic of serotype M1 group A Streptococcus infection

Nancy P. Hoe, Jaana Vuopio-Varkila, Martti Vaara, Diana Grigsby, David De Lorenzo, Yun Xin Fu, Shu Jun Dou, Xi Pan, Kazumitsu Nakashima, James M. Musser

Research output: Contribution to journalArticlepeer-review

Abstract

Streptococcal inhibitor of complement (Sic) is a highly polymorphic extracellular protein made predominantly by serotype M1 group A Streptococcus (GAS). New variants of the Sic protein frequently appear in M1 epidemics as a result of positive natural selection. To gain further understanding of the molecular basis of M1 epidemics, the sic gene was sequenced from 471 pharyngitis and 127 pyogenic and blood isolates recovered from 598 patients living in metropolitan Helsinki, Finland, during a 37-month population-based surveillance study. Most M1 GAS subclones recovered from pyogenic infections and blood were abundantly represented in the pool of subclones causing pharyngitis. Alleles shared among the pharyngitis, pyogenic, and blood samples were identified in throat isolates a mean of 9.8 months before their recovery from pyogenic infections and blood, which indicates that selection of most sic variants occurs on mucosal surfaces. In contrast, no variation was identified in the emm and covR/covS genes.

Original languageEnglish (US)
Pages (from-to)633-639
Number of pages7
JournalJournal of Infectious Diseases
Volume183
Issue number4
DOIs
StatePublished - Feb 15 2001

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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