Enhanced resistance to streptococcal infection induced in mice by cell wall mucopeptide.

The streptococcal cell wall mucopeptide when injected into mice either intraperitoneally or intravenously enhances the resitance to subsequent challenge with virulent Group A streptococci. Rabbits which are injected intravenously with solubilized mucopeptide develop a fever response which has a resemblance to that achieved with endotoxin. Mice which survive 6 to 7 weeks after challenge with virulent Group A streptococci yield at autopsy search Group A streptococci serologically identical to the challenge organisms. A preparative dose of cell walls injected into mice prior to challenge diminished this late recovery of streptococci. Group A-variant streptococci were recovered from mice which survived challenge and carried the organisms for several weeks. Filterable bacterial forms, which grew on L form media, were recovered from infected mice. The serologic type of the L forms was identical to that of the challenge organisms.