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Stopping Superantigens

The structural biology of superantigens, amongst other bacterial toxins, is under the microscope in a new research project. Professor Ted Baker of Massey University has received a Health Research Council grant to look at the three-dimensional structure of a number of such toxins. His research group will collaborate with Dr John Fraser of the Auckland School of Medicine, who will supply the needed toxins in a pure form.

"Toxins such as these can cause scarlet fever, rheumatic fever, toxic shock syndrome. These are potentially life threatening illnesses," says Baker.

Superantigens attack the immune system, over-stimulating it and causing the uncontrolled release of powerful immune regulators called cytokines. If the victim survives the high levels of cytokines, which can cause severe shock and death, they are then faced with a disabled immune system which in effect simply switches off for a while and takes some time to recover.

"The superantigens work by binding to some of the molecules that make up the immune system," explains Baker. "That is why we need to find out the three-dimensional structure -- to work out at what sites the antigen is binding and doing damage."

The first aim of the group is to establish the structure of the superantigen through X-ray crystallography. Then they will make complexes of it with the molecules it binds to, in order to see how it binds.

Baker says that if they know which parts of the superantigen cause the effects,, it may be possible to manufacture drugs which attach to the superantigen at its binding site, preventing it from binding to anything else. Also, if the discoveries mean that the antigens can be controlled, they could be used in future to stimulate the immune system.