Thesis (Ph.D.)--Boston University. / The purpose of the studies presented in this paper was to attempt to elucidate the nature of the substance contained in staphylococcal culture filtrates which are responsible for their ability to hemolyze mammalian erythrocytes, particularly those of the sheep and the rabbit. The work was centered upon the selection of strains capable of producing filtrates of potent hemolytic activity; a study of several methods or hemotoxin production to improve this ability, and of filtration to ensure minimal loss of hemotoxic fractions; the standardization of a spectrophotometric method for accurate determinations or 50% hemolytic end-points; the definition or conditions required for separation of the hemolytic principles from culture filtrates and for their optimum yield and purity; and some of the properties or the hemalysins. A review of the literature concerning the various phases of the problem is given. Many methods have been described for the production of staphylococcal toxins, the more recent of these involving the use or chemically defined liquid media. It has been generally agreed that strains of Staphylococcus aureus also require the presence of CO2 in the atmosphere for adequate production of the hemolysins. Opinions have differed, however, as to the amount of CO2 required, and also concerning the length of the culture period required for peak toxin production. [TRUNCATED]

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Staphylococcus aureus (S. aureus) is a frequent cause of infections and sepsis in animals and humans worldwide. Staphylococcal enterotoxins and toxic shock syndrome toxin-1 are bacterial superantigens (SAgs) produced by S. aureus that simultaneously bind to T cell receptor (TCR) and the major histocompatibility complex (MHC) class II, leading to extensive T cell stimulation, release of cytokines, consequently resulting in toxic shock and immunosuppression. In this study, we generated mutant SAgs by introducing alanine substitution at residues involved in interaction with MHC class II and TCR binding and demonstrated attenuation of toxicity in vitro and in vivo. An immunization with mutant SAgs elicits production of neutralizing antibodies against wild type SAgs and protected animals from S. aureus peritonitis at a lethal dose. These results suggest that mutant SAgs will be useful to develop a novel vaccine against S. aureus infections.

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