Children with acute rheumatic fever present with significantly more serologically-confirmed group A Streptococcus infections compared with healthy children in the same environment, according to study results published in Clinical Infectious Diseases.
A team of investigators who were previously able to map a patient’s prior group A Streptococcus infections via serum antibody characterization, conducted a study to serologically determine whether children who develop acute rheumatic fever experience more group A Streptococcus infections compared with children without disease, and to assess the role of immune priming in acute rheumatic fever pathogenesis.
Group A Streptococcus strains are often identified by emm-type, which correspond to the hypervariable region of the N-termini of M-proteins; strains can be categorized further into emm-cluster types based on M-protein structure and function.
A total of 33 matched case-controlled pairs were included in the analysis and screened for reactivity against a series of M-type specific peptides. Quantitative enzyme-linked immunosorbent assays (ELISAs) were performed against the peptide panel to detect serum antibodies.
Serum profiles resulted in antibodies to a broad range of M-types; no 2 patients had prior exposure to the same suit of M-types. In addition, all patients with acute rheumatic fever had antibodies for at least 2 different M-types; 90.9% has antibodies to at least 5 M-types. Antibodies for less than 5 M-types were recorded in 57.5% of healthy individuals.
Results from a pair-wise comparison of M-type antibodies revealed significantly more serologically-confirmed group A Streptococcus exposures among patients with acute rheumatic fevers compared with healthy controls (P<.0001). There was no confirmed association between specific M-type antibodies and acute rheumatic fever, or significant differences in strain patters between patients and healthy controls.
“This study used a novel serological approach to profile previous [group A Streptococcus] exposures by measuring M-type specific antibodies in sera, with long peptides derived from the hypervariable region of the corresponding m-protein as antigens,” the study authors noted.
“[O]ur study shows [that] children who develop [acute rheumatic fever] have experiences approximately three times as many [group A Streptococcus] infections as healthy children living in similar environments,” wrote the investigators.
Lorenz N, Ho TK, McGregor R, et al. Serological profiling of group A streptococcus infections in acute rheumatic fever. Clin Infect Dis. Published online February 26, 2021. doi:10.1093/cid/ciab180