- NEW YORK - By identifying
a compound that changes the nature of an infectious agent, researchers
have taken a step toward treating spongiform encephalopathies, a group
of fatal brain disorders that includes 'mad-cow' disease.
- Although such diseases are rare in humans, identifying
a treatment has become even more important since an outbreak of 'mad-cow'
disease in cattle in Great Britain in the 1980s and early 1990s.
- It is thought that a new type of Creutzfeldt-Jakob disease
(CJD) " an incurable and rapidly fatal illness seen in a handful of
young adults in the UK " may be linked to consuming meat from cattle
with 'mad-cow' disease.
- According to a report in the January 15th issue of The
Lancet, researchers have discovered a peptide known as iPrP13 that interferes
with the structure of the prion, the infectious agent thought to be the
cause of spongiform encephalopathies. The prion accumulates in the brain,
triggering biochemical changes that lead to dementia, an inability to talk
or walk and ultimately, death.
- Dr. Claudio Soto of New York University Medical Center
and Serono Pharmaceutical Research Institute in Geneva, Switzerland, and
colleagues extracted prions from the brains of mice and humans who had
died of spongiform encephalopathy.
- The investigators found that the iPrP13 peptide helped
break down the prions in laboratory studies. When the peptide was added
to the prions and both were injected into mice, the rodents tended to survive
for a longer period of time before succumbing to the fatal disorder. The
authors estimate that the peptide decreased the infectious nature of the
prion by 90% to 95%.
- The authors suggest that the findings may help to design
treatments of infectious spongiform encephalopathies. The peptides "could
represent prototype compounds for the development of new treatments that
prevent or reverse... changes implicated in transmissible spongiform encephalopathies,"
the study concludes.
- However, there are a number of problems with peptides
that make them inadequate for treating human illness. The peptides tend
to be degraded or attacked by the immune system before they reach their
target, and it is very difficult to get them into the brain to interact
- "There is still a lot of work to be done before
we can use these peptides in the actual treatment of the disease,"
said Soto in a statement issued by The Lancet. "However, this concept
may represent a novel approach for the rational design of drugs that may
prevent protein conformational changes implicated in a variety of diseases."