Evidence has been presented that Group C bacteriophages differ as to their inactivating site on the streptococcal cell wall. While all three phages adsorb to isolated cell walls, only the C1 phage was inactivated by enzymatically prepared group-specific carbohydrate. None of the Group C phages were inactivated by chemically extracted group-specific carbohydrate. In contrast, all virulent Group A streptococcal bacteriophages adsorbed only to living Group A streptococci. However, Group A temperate phages were able to adsorb to isolated cell walls but not to group-specific carbohydrate.
While it has not been possible to identify the specific inactivating substance for the Group A virulent phages, certain pieces of evidence indirectly implicate the group-specific carbohydrate, specifically the N-acetylglucosamine moiety. The fact that Group A virulent phages failed to adsorb to heat-killed Group A streptococcal cells suggests that additional factors produced by the living cell are needed for complete viral inactivation.