Open AccessVariable Susceptibility to Opsonophagocytosis of Group A Streptococcus M‐1 Strains by Human Immune Sera
Author(s) -
Alberto VillaseñorSierra,
W. Michael McShan,
Daniel B. Salmi,
Edward L. Kaplan,
D. R. Johnson,
Dennis L. Stevens
Publication year - 1999
Publication title -
the journal of infectious diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.69
H-Index - 252
eISSN - 1537-6613
pISSN - 0022-1899
DOI - 10.1086/315120
Subject(s) - antibody opsonization , microbiology and biotechnology , biology , antibody , phagocytosis , immune system , streptococcus , immunity , bacteria , strain (injury) , virology , opsonin , immunology , genetics , anatomy
Immunity to group A streptococci (GAS) is thought to be related to the acquisition of type-specific antibody directed against the M protein. However, recent work suggests that immunity may only be strain and not M-type specific. Therefore, susceptibility of 70 different GAS M-1 strains to opsonization and killing by convalescent sera was compared by using a highly sensitive chemiluminescence assay and by standard bactericidal assay. Sequencing of the emm1 gene in 10 strains with variable susceptibility to opsonization revealed 100% homology in 9 strains. Several substitutions in the N-terminal and 2 in the A3 repeat regions of strain CS-190 were associated with profound resistance to opsonization. Thus amino acid substitutions within different regions of the M-1 protein molecule may adversely affect opsonization by immune sera. In addition, non-M protein factors from identical M types influence susceptibility to phagocytosis. These findings may in part explain the persistently high prevalence of M-1 strains worldwide over the last 15 years.
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