November 11, 2004 United Press International

Transgenic mice injected with the pathogen that causes the human form of mad cow disease, known as variant Creutzfeldt Jakob disease, also developed sporadic CJD as well as what appeared to be a novel form of the fatal illness, John Collinge and colleagues at University College in London reported in the journal Science.

It has been known since the 1990s that mad cow disease could cause vCJD in people, but some animal studies have suggested it might also cause sporadic CJD, although this has not been confirmed in humans.

This latest research indicates the type of CJD a person develops may depend on their genes as well as the genes of the source of the mad cow pathogen, which is thought to be a misfolded protein called a prion.

Mice with the MM genotype -- the same makeup found in all 146 people in England who have died of vCJD -- developed vCJD. Mice with a different genetic profile, found in the majority of people, either didn't come down with an illness, developed sporadic CJD or developed a new form of CJD.