S. pyogenes M protein is the major virulence factor, and certain regions of its N-terminus can trigger autoimmune sequelae such as rheumatic fever in susceptible individuals with untreated group A streptococcal pharyngitis.
We identified several M protein epitopes recognized by peripheral T cells of RF/RHD patients and by heart tissue infiltrating T cell clones of severe RHD patients.
In this study, we investigated the hypothesis that streptococcal M protein could produce inflammatory valvular heart lesions similar to those seen in rheumatic fever (RF).
A resurgence of invasive streptococcal diseases and rheumatic fever has appeared in outbreaks over the past 10 years, with a predominant M1 serotype as well as others identified with the outbreaks. emm (M protein) gene sequencing has changed serotyping, and new virulence genes and new virulence regulatory networks have been defined.
All three strains studied possess the conserved region domain common to class I group A M-protein types epidemiologically associated with rheumatic fever.
IgG titers against the C region of M protein were measured by ELISA from sera of patients with RF (n = 10), uncomplicated streptococcal pharyngitis (n = 26), and age-matched controls (n = 49).