Growth of group B streptococci and development of surface antigens in tissue cages implanted in rabbits.

Using tissue cages implanted in rabbits the growth of some strains of group B streptococci and the development of cell surface antigens were analyzed and compared to those under in vitro conditions. Two encapsulated strains grew well in the tissue cage fluid. Their capsules could be heavily labelled by ferritin-conjugated antibody against the type-specific polysaccharide. However, the thickness of the capsule was different to that following cultivation in vitro. In both strains the labelling of the group polysaccharide in the cell wall was sterically hindered by the large capsule. Two strains lacking a capsule did not grow in the tissue cage fluid but were mostly phagocytized. This again demonstrates the importance of the type-specific polysaccharides as significant virulence factors of group B streptococci.