The successful classification of Group A streptococci by the capillary precipitin technique requires a complete series of M type antisera which are sufficiently potent and specific to give unequivocal type-specific reactions with all the serotypes. Specific antisera for this purpose have been prepared by absorption with heterologous streptococci. Unabsorbed antisera have been employed here in the Ouchterlony double-diffusion agar-gel test to identify the M type of streptococci. Techniques have been developed for making this method of M typing fully reliable. The results reported here confirm and amplify the original findings of Michael and Massell (3). With crude HCl extracts and unabsorbed M type antisera, a precipitin line due to the M protein and another to the group-specific carbohydrate are the two major reactions observed. These reactions, however, are usually readily distinguishable. There was a surprising lack of cross-reactive precipitin lines due to non-type-specific protein antigens in the extracts. Although many of the unabsorbed M type antisera can be employed in the double-diffusion tests, the group-specific antibody must be removed from some of the unabsorbed antisera to avoid confusing cross-reactions. Absorption of these antibodies has been achieved by means of a specific immunoabsorbent column prepared from para-aminophenyl-ß-N-acetylglucosamine and cyanogen bromide-activated Sepharose. Excellent agreement was observed between the M typing results obtained on 117 field strains by the conventional capillary precipitin method and the Ouchterlony double-diffusion method.

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.

1'9 8 STREPTOCOCCAL L FORMS normal level, an abnormally high LD5 isoenzyme fraction may be an indication of the lack of total correction of the abnormalities present during the acute phase of the disease. As such, this may be a sign of the need of more active therapy.

Although the mucopeptide ~ of hemolytic streptococci is not chemically similar to the endoto~n~ of Gram-negative bacteria, both substances have several biological properties in common. For example, streptococcal mucopeptide, when injected into mice, either intraperitoneaUy or intravenously, enhances the resistance to subsequent challenge with virulent Group A streptococci. Mucopeptide produces fever in the rabbit and may initiate shock and death (1). A necrotic skin lesion develops in rabbits after local injection of mucopeptide (2). In this report, the febrile response after injection of mucopeptide has been studied in greater detail, and mucopeptide has been used to prepare and provoke the local Shwartzman reaction. Special attention has been given to pathologic alterations which occur in the myocardium of rabbits after the intravenous administration of mucopeptide, a finding which was reported earlier as a preliminary observation (3). Throughout the whole procedure for the preparation of mucopeptide and carbohydrate, from the growth of the bacteria to the final lyophifization of the products, care was taken to * The prellmlna~ studies of this work were begun at the time the senior author was a visitiag investigator in the laboratory of Dr. Materials and Methods Streptococcal Strains.--Group

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