Biological activity of toxic shock syndrome toxin 1 and a site-directed mutant, H135A, in a lipopolysaccharide-potentiated mouse lethality model

Abstract

A recombinant of toxic shock syndrome toxin 1 (TSST-1) which contains a single histidine-to-alanine mutation at residue 135 (H135A) was analyzed for toxicity and vaccine potential in a lipopolysaccharide (LPS)-potentiated mouse lethality model. The 50% lethal dose (LD 50) of TSST-1 in BALB/c mice was 47.2 g/kg, but H135A was not lethal when tested at a dose equivalent to 10 LD 50 s of TSST-1. Levels of tumor necrosis factor (TNF) and gamma interferon (IFN-␥) in serum were, respectively, 10-and 50-fold higher in LPS-potentiated mice injected with 15 LD 50 s of TSST-1 than in mice given H135A. Mice injected with only TSST-1 did not have elevated levels of TNF or IFN-␥ in serum, while H135A plus LPS or LPS alone elicited identical, yet very low, levels of TNF and IFN-␥. An enzyme-linked immunosorbent assay of H135A and TSST-1 with anti-TSST-1 serum yielded very similar dose-response curves, which strongly suggests that H135A serologically and conformationally resembles the native toxin. Mice immunized with H135A developed antibodies that recognized TSST-1 in an enzyme-linked immunosorbent assay and afforded protection against a 15-LD 50 challenge of TSST-1 plus LPS. The pooled sera of mice immunized with either TSST-1 or H135A also prevented lymphocyte proliferation due to TSST-1.

Immunization with glutathioneS-transferase and mutant toxic shock syndrome toxin 1 fusion protein protects againstStaphylococcus aureusinfection

“…In striking contrast to the 76% mortality rate of TSST-1 at 10 lg per mouse plus LPS, none of the mice died when injected with an equivalent dose of GST-mTSST-1 plus LPS. The lack of toxicity by GST-mTSST-1 in LPS-potentiated mouse model corresponded well to previous results of in vivo assay [37].…”

“…Gampfer et al [44] demonstrated that vaccination with non-superantigenic SEB and TSST-1 developed antibody responses against these toxins and protected against challenge with lethal doses of superantigen potentiated with LPS. mTSST-1 has been previously described and extensively studied [27,37]. In the present study, we were interesting in whether vaccination with GST-mTSST-1 fusion protein could protect against S. aureus infection.…”

Superantigenic activity of toxic shock syndrome toxin-1 is resistant to heating and digestive enzymes

“…The toxic effect of treated SEA and TSST-1 was tested in LPS-potentiated mouse lethality model (Stiles et al 1995).…”

“…To further analyse the superantigenic activity of treated toxins, we examined whether the toxicity is also detected in a lethal enterotoxin shock model in vivo (Stiles et al 1995). Mice were injected with LPS plus heat-treated or digestive enzyme-treated toxins, and the lethal effect was determined.…”

Refined structures of three crystal forms of toxic shock syndrome toxin‐1 and of a tetramutant with reduced activity

“…In the TSST-1 :MHC complex the MHC contacts the front of Domain B below this ridge (Kim et al, 1994). The majority of the mutations that reduce superantigenicity Murray et al, 1994;Hurley et al, 1995;Stiles et al, 1995) are on the back of this ridge in Domain A suggesting that is where the TCR interacts with TSST-1. This differs from the staphylococcal enterotoxins where mutations Kappler et al, 1992;Pontzer et al, 1992;Hudson et al, 1993) and the recent crystal structure of SEC3 and the TCR p chain (Fields et al, 1996) show a TCR interaction surface reaching from the top of Domain B to t h e e n t of Domain A.…”