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REPEATED PASSAGE OF FRESHLY ISOLATED GROUP A STREPTOCOCCI ON BLOOD AGAR I. Effect on M Protein, Opacity Factor and IgG Fc‐Receptor Activity
Author(s) -
STJERNQUISTDESATNIK ANNA,
KURL DAYA N.,
CHRISTENSEN POUL
Publication year - 1984
Publication title -
acta pathologica microbiologica scandinavica series b: microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0108-0180
DOI - 10.1111/j.1699-0463.1984.tb02825.x
Subject(s) - microbiology and biotechnology , subculture (biology) , biology , agar , receptor , chocolate agar , antibody , agar plate , bacteria , immunology , biochemistry , genetics
Seventy‐six strains, 20 T‐type 1, 20 T‐type 2, 18 T‐type 4 and 18 T‐type 12 group A streptococci were isolated from throat cultures and subjected to 25 serial passages on blood agar. A single “glossy” colony was selected from each passage in order to diminish the M protein content of the strains. In accordance with previous results, the M protein synthesis, as estimated by an electro‐immuno assay diminished in the T1 strains, in mean from 23.8 to 15.5% of a reference M protein preparation (p <0.01). Opacity factor (OF)‐production was used as a measure for M protein in the T‐type 2, the T‐type 4 and the OF‐positive T‐type 12 strains. OF‐excretion decreased significantly in the T‐types 2 and decreased, though not significantly in the T‐type 12 strains but increased (unexpectedly) in the T‐type 4 isolates during subculture. However, irrespective of the changes in M protein/OF production these types all increased significantly in capacity to bind radiolabelled IgG via the Fc‐fragment. It is known that streptococci isolated during convalescence resemble subcultured strains; it is suggested that IgG Fc‐receptors are important for protection of the streptococci against phagocytosis in the asymptomatic carrier state.