Alteration of proteins reacting with antibody to toxic shock syndrome toxin 1 by endogenous proteases of Staphylococcus aureus.

Many cases of toxic shock syndrome (TSS) have been associated with Staphylococcus aureus strains that produce in vitro a 22,000-dalton protein called toxic shock syndrome toxin 1 (TSST-1). TSST-1 has been shown to be linked phenotypically to the production of the type II (thiol) staphylococcal protease; however, some strains clearly associated with TSS do not produce TSST-1. With the use of a variety of antibodies to TSST-1, representatives of both TSST-1-positive and TSST-1-negative TSS-associated strains were shown to produce proteins of 32,000, 53,000, and 76,000 daltons that cross-reacted with TSST-1 but that did not appear to be TSST-1 aggregates or to be protein A. TSST-1-negative strains were significantly (P less than .05) more likely than TSST-1-producing strains to produce the type I protease and less likely to produce the type II protease. In vitro the type I (serine) protease digests purified TSST-1. When combinations of type II and type III protease chemical inhibitors were used, the production of the high-molecular-weight cross-reacting proteins during in vitro growth could be selectively enhanced. Since the infected foci (e.g., abscess, vagina) associated with TSS may contain natural protease inhibitors, it is possible that such TSST-1 cross-reacting proteins may be expressed in vivo or that levels of TSST-1 may be increased by an inhibitor of the serine protease.