[The biochemical and immunological properties of group A type M 29 streptococci cultured in the presence of a bovine blood serum preparation].

The influence of the preparation of cattle blood serum on group A streptococcus, type M 29, has been studied. The study has revealed that the addition of 17% of dialysis water obtained from a fraction of cattle blood serum to the standard culture medium (3% Todd-Hewitt broth) produces changes in the amino acid composition of the cell walls of M+ variant without altering the antiphagocytic resistance of the mutant thus obtained. The dialysate of the pepsin digest of the cell walls of the mutant contains Fc-receptors and receptors to fibrinogen, while the initial strain contains only receptors to fibrinogen which are, in this case, the pepsin fragments of M protein. The study has revealed similarity in the amino acid compositions of these proteins (receptors to fibrinogens) of phenotypes M+ and M2+. Thus, our data confirm that the initial strain and the mutant belong to different phenotypes of group A streptococcus, type M 29.