Bacteriology: Blocking superantigens
Superantigens are a group of potentially fatal bacterial toxins produced by Staphylococcal and Streptococcal bacteria. These superantigens induce an extreme immune reaction, one with a magnitude much higher than a regular response. This is known as an "immune storm". Fatality occurs when the immune storm causes toxic or septic shock to the patient.
Researchers from the Hebrew University Faculty of Medicine discovered that superantigens must first bind to a human immune cell surface protein receptor called CD28 before it can initiate the immune storm. CD28 is a vital receptor that is involved in almost every immune response, however the ability of the receptor to bind the superantigen was virtually unheard of before this investigation.
Mapping out the exact binding region between CD28 and the superantigen, the research team designed decoys, small protein fragments that are highly similar to the binding area of CD28. These decoys were able to block the superantigens from binding to the actual CD28 molecule, protecting the test animals from the extreme immune response and sparing them from suffering the usual fatal outcome.
The decoy proteins are a possible therapy for Staphylococcal or Streptococcal bacteria-induced toxic shock. Since this therapy is host-orientated, meaning that it is directed toward the human immune system instead of against a pathogen, bacterial resistance is unlikely to become an issue.
