Updated model of group A Streptococcus M proteins based on a comprehensive worldwide study

Abstract

Background Group A Streptococcus (GAS) M protein is an important virulence factor and potential vaccine antigen, and constitutes the basis for strain typing (emm-typing). Although >200 emm-types are characterized, structural data were obtained from only a limited number of emm-types. were aim to evaluate the sequence diversity of near-full-length M proteins from worldwide sources and analyse their structure, sequence conservation and classification. Methods GAS isolates recovered from throughout the world during the last two decades underwent emm-typing and complete emm gene sequencing. Predicted amino acid sequence analyses, secondary structure predictions and vaccine epitope mapping were performed using MUSCLE and Geneious software. Results 1086 isolates from 31 countries were analysed, representing 175 emm-types. emm-type is predictive of the whole protein structure, independent of geographic origin or clinical association. Findings of an emm-type paired with multiple, highly divergent central regions were not observed. M protein sequence length, the presence or absence of sequence repeats, and predicted secondary structure was assessed in the context of the latest vaccine developments. Conclusions Based on these global data, the M6 protein model is updated to a three representative M protein (M5, M80, M77) model, to aid in epidemiological analysis, vaccine development and M protein-related pathogenesis studies.

Epidemiology Analysis of Streptococcus pyogenes in a Hospital in Southern Taiwan by Use of the Updated emm Cluster Typing System

“…emm pattern typing is another typing method that is based on the presence and arrangement of emm and emm-like genes in the GAS genome (25). emm pattern typing has been shown to correlate significantly with tissue tropism; however, only a small proportion of specific emm pattern strains have been extensively studied (22,26).A new typing method, emm cluster typing, which is based on the nearly complete sequence of the emm gene, has been proposed (24). This typing system classifies emm types into 48 discrete emm clusters.…”

“…emm typing is the most widely used molecular typing approach, and more than 200 different emm types have been reported worldwide (21)(22)(23). However, since emm typing is based on a small portion of the emm gene, this typing method provides limited information about the predicted conformational structure or functional domains of the M protein (24).…”

“…emm pattern typing is another typing method that is based on the presence and arrangement of emm and emm-like genes in the GAS genome (25). emm pattern typing has been shown to correlate significantly with tissue tropism; however, only a small proportion of specific emm pattern strains have been extensively studied (22,26).…”

Streptococcus pyogenes emm Types and Clusters during a 7-Year Period (2007 to 2013) in Pharyngeal and Nonpharyngeal Pediatric Isolates

“…The N terminus consists of a highly variable amino acid sequence, resulting in antigenic diversity, and is the basis for a nucleotide-based emm-typing scheme (9). There are at least 220 different emm types and subtypes of GAS, and new types are still being identified (8,10,11). Temporal, geographic, and seasonal variations in the dominant strains are well described and can result in variable epidemiological characteristics of disease (12).…”

Genome-wide analysis of Streptococcus pyogenes associated with pharyngitis and skin infections. (c2015)

“…It is noteworthy that the detected combinations of MLST clones and emm types are mostly associated with upper respiratory tract and skin infections with some reported as being invasive (Enright et al, 2001;McMillan et al 2013). …”