[48] Chick embryo assay for staphylococcal toxic shock syndrome toxin-1

This chapter describes the chick embryo assay for staphylococcal toxic shock syndrome toxin-1 (TSST-1). TSST-1 is produced by the strains of Staphylococcus aureus associated with toxic shock syndrome, an acute, febrile disease in man leading to cardiovascular shock. TSST-1 is pyrogenic, causes shocklike symptoms, and is lethal in rabbits. Other biological effects include lymphocyte mitogenicity, release of interleukin-1 from monocytes, and potentiation of chick embryo lethality because of gram-negative lipopolysaccharide (LPS). The enhancement of chick embryo lethality can be used as a bioassay for TSST-1 in the presence of a fixed sublethal amount of LPS. Assays based on the mitogenic effect and the ability to induce release of interleukin-1 from monocytes, although sensitive, are fairly complex to perform and require the use of tissue culture facilities. The chick embryo assay is easily executed, sensitive, and reproducible. However, it should be noted that the assay may not be suitable for crude culture supernatants from TSST-1+ strains because staphylococcal products other than TSST-I may be lethal in chick embryos.