Binding of human fibrinogen and its polypeptide chains to group B streptococci.

Of 51 group-B streptococcal cultures, 20 bound 125I-labelled human fibrinogen. In contrast to the streptococci of groups A, C and G, the group-B streptococci interacted more with the alpha, beta-chain of fibrinogen than with whole fibrinogen. None of the streptococcal cultures reacted with gamma-chain. The fibrinogen-negative group-B streptococci still bound the alpha, beta-chain. The binding of 125I-labelled, alpha, beta-chain could be inhibited by unlabelled fibrinogen with fibrinogen-positive, but not with fibrinogen-negative streptococci of group B.