Longitudinal Analysis of Group A Streptococcus emm Types and emm Clusters in a High-Prevalence Setting: Relationship between Past and Future Infections

Abstract

Group A Streptococcus is a pathogen of global importance, but despite the ubiquity of group A Streptococcus infections, the relationship between infection, colonization, and immunity is still not completely understood. The M protein, encoded by the emm gene, is a major virulence factor and vaccine candidate and forms the basis of a number of classification systems. Longitudinal patterns of emm types collected from 457 Fijian schoolchildren over a 10-month period were analyzed. No evidence of tissue tropism was observed, and there was no apparent selective pressure or constraint of emm types. Patterns of emm type acquisition suggest limited, if any, modification of future infection based on infection history. Where impetigo is the dominant mode of transmission, circulating emm types either may not be constrained by ecological niches or population immunity to the M protein, or they may require several infections over a longer period of time to induce such immunity.

Application of the random forest algorithm to Streptococcus pyogenes response regulator allele variation: from machine learning to evolutionary models

“…This represents an important finding in the evolutionary history of E3 GAS. Our findings are also epidemiologically important, because E3-type isolates have recently been identified in outbreaks as the causative agent of severe GAS disease 18 , 32 – 35 . Furthermore, given that emm is a major focus in GAS vaccine development, we consider that this work increases our understanding of rare and anomalous mga regulons.…”

Two Streptococcus pyogenes emm types and several anaerobic bacterial species are associated with idiopathic cutaneous ulcers in children after community-based mass treatment with azithromycin

“…In the South Pacific, where our specimens for this study originated, impetigo is the predominant form of S . pyogenes infection [ 38 ]. Until our studies on the Lihir Island cohort, S .…”

“…Due to a lack of infrastructure, cultures are not done on children with pharyngitis or impetigo on Lihir Island; thus, the circulating emm types are unknown. Longitudinal analysis of emm types in a high prevalence setting of pharyngitis and impetigo in Fiji detected that 19–37 emm types circulated during six screening periods conducted every 2 months in school-based settings, that the 5 most frequent emm types accounted for only ~30% of the isolates, and that there was no evidence of tissue tropism for the emm types [ 38 ]. Whether the 2 emm types found in our study are unique to CU or reflect the emm types circulating on Lihir Island remains to be determined.…”

Rheumatic heart disease: A review of the current status of global research activity

“…However, numerous studies and clinical data confirm that: humans produce antibodies to a range of cell-wall associated and secreted Strep A antigens; some of these antibodies confer protection against reinfection with homologous and partially heterologous Strep A emm types; and antibody titres tend to be higher in adults than in children suggesting that protective immunity develops slowly after years of exposure [69][70][71].…”