Antigenic mimicry is the sharing of antigenic sites between microorganisms and mammalian tissue. An immune response can be directed both at the microorganism and at the host site that shares the antigenic determinant. This autoimmune response due to antigenic mimicry is known to be a crucial factor in the development of certain ailments in humans.

The immune system recognizes three-dimensional structure of protein. A protein, which is made up of a sequence of amino acids strung together, will fold up in various ways, depending on whether a section is more hydrophilic ("water loving") or hydrophobic ("water hating"), and depending on the function of various regions of the protein.

Proteins that adopt a similar three-dimensional configuration can stimulate a common response...