Double mutant and formaldehyde inactivated TSST-1 as vaccine candidates for TSST-1-induced toxic shock syndrome

Up to now, there is no treatment for staphylococcal toxic shock syndrome, a disease mainly induced by toxic shock syndrome toxiti-1(TSST-1). There is great demand in finding means to control the disease. one of them is the development of an effective and safe vaccine against TSST-1. In this study we constructed a series of vaccine candidates and investigated their biological activity, toxicity, and potential to invoke an immune response. TSST-1 was isolated from Stahylococcus aureus supernatants and recombinantly expressed as a N-terminal 6x histidine-tagged protein in Escherichia coli. In order to obtain molecules with minimal toxicity we constructed single mutants (G31R and H135A) and one double mutant (G31R/H135A) with both residues exchanged. We also de toxified native TSST-1 isolated from S. aureus. and recombinantly expressed TSST-1 by treatment with formaldehyde. Functional activity of native and recombinant TSST-1 and grade of inocuity of mutants and toxoids was determined by investigating mitogenity, T-cell activation, and cytokine release upon stimulation of human mononuclear cells with the vaccine candidates. All substances were tested in a rabbit immunization study. After primary immunization and three additional boosts all vaccinated animals developed antibody titers against TSST-1 and were protected against challenge with a lethal doses of superantigen potentiated with lipopolysaccharide. (C) 2002 Elsevier Science Ltd. All rights reserved.