By Sean Henahan, Access Excellence

LONDON (10/23/96) Sophisticated genetic analyses now indicate that human victims of a recent wave of Creutzfeldt-Jakob disease (CJD) in England did indeed become infected through the consumption of beef. infected with the related prion disease, bovine spongiform encephalopathy, or 'mad cow disease'. While public authorities in England had already suggested this was probably the case, the new study provides the first hard evidence of the link between eating beef and developing CJD.

When the CJD/BSE outbreak was first reported by health authorities it was already clear that a new variant of CJD was being seen in humans. This was apparent both from the young age of the victims and from the distinct pattern of brain damage revealed in subsequent autopsies. Until now, autopsy studies or time-consuming animal studies.

Researchers in the Prion Disease Group at the Imperial College School of Medicine, London have developed a new test using the biochemical properties of the prion protein thought to cause the disease to trace the origin of the new form of the disease. They found that the biochemical signature of prions in patients who died from the new variant matches that of prions in mice and macaque monkeys experimentally infected with BSE, but differs from that of prions in human patients with other known forms of the disease (acquired or sporadic CJD).

The researchers performed a series of genetic studies on the frozen brain tissue from victims of both the new and original forms of CJD. DNA was extracted from the tissues and analyzed fro the presence of known or new coding mutations in the prion protein gene. The samples then were subjected to PCR, fractionated and sequenced. Distinct glycoform 'signatures' were observed corresponding to each the disease variants.

The recent British victims are presumed to have become infected by eating beef before 1989, when a ban feeding processed bovine offal to cattle was put in place. The new findings strongly support the conclusion that new variant of CJD is a consequence of the BSE epidemic in British cattle. The new diagnostic technique could also form the basis of a rapid diagnostic test for these diseases in both humans and animals. In related research, investigators at the NIH reported the development of a potential CJD test that measures spinal fluid

Some 15% of cases of CJD are acquired genetically (with an autosomal dominant pattern of inheritance) with the remainder either occuring in a little understood sporadic form or in assocation with cannabilistic practices (Kuru) or via transplants of infected tissue.

The research appears in Nature, 10/24/96.