X-Message-Number: 13292
Date: Thu, 24 Feb 2000 22:21:49 -0500
From: Jan Coetzee <>
Subject: Vaccine to protect brain

Report: Vaccine Protects Against Stroke, Epilepsy

WASHINGTON (Reuters) - Researchers said on Thursday a new approach
combining gene
therapy and vaccination has prevented epileptic seizures and brain
damage in rats and suggested
it could eventually be tried in humans.

A team at the Jefferson Medical College in Philadelphia said their
vaccine, which is given
orally, marshaled the immune system to protect brain cells that are
usually killed during and after
a stroke or a seizure.

``It protects them significantly from ... insults such as an epileptic
seizure or a stroke for at least
five months after a single oral dose,'' Dr. Matthew During, a professor
of neurosurgery who led
the study, said in a statement.

The researchers, who reported their findings in the journal Science,
said it might be used to help
protect people considered at high risk of a stroke or a seizure, such as
those who have undergone
heart bypass surgery.

And they say the approach might work against a whole range of diseases
involving the central
nervous system, from Parkinson's to Lou Gehrig's disease (motor neuron

``I think it represents a new platform of technology, a sort of
revolutionary approach to the
treating of brain diseases,'' During said in a telephone interview.

``What we have shown here is you can harness the amazing specificity of
the immune system so it
can go in and act as a scalpel, so to speak, to target specific brain

During and colleagues, working in collaboration with the team at the
University of Auckland in
New Zealand, targeted a brain protein, part of the NMDA receptor. This
bit of the receptor --
which is a chemical doorway into a brain cell -- is called NR1.

NMDA receptors are important not only for brain development and
learning, but are involved in
a range of diseases including epilepsy, dementia and the injuries caused
by stroke.

The researchers made up a vaccine that caused the rats to first produce
the protein for this
receptor, then recognize it as abnormal and block it. Best of all, the
effect was temporary and
seemed to work only in direct response to a brain injury.

They used an adeno-associated virus -- a small kind of virus that does
not make people sick but
which is very good at infecting cells -- to carry DNA from the NMDA
receptor into the bodies of
their experimental rats.

They fed this vaccine to the rats, who developed antibodies specifically
targeting this bit of the
receptor, and when the scientists induced an epileptic seizure in the
rats a month later, only 2 of 9
vaccinated rats showed signs of a seizure.

``About 70 percent of the rats should have gone into seizures, whereas
only 20 percent of the rats
immunized against the NMDA receptor did so,'' During said.

They killed the rats and looked at their brains and found no sign of the
damage usually caused by
the chemical used to induce a seizure. During thinks the effect might be
permanent, but they have
to test the rats further to see if they are protected against repeated
injuries or seizures.

The brain is exceptionally fragile because, for reasons not yet fully
understood, when one brain
cell dies, as in a blow to the head or a stroke, it sends out signals
that kill other, uninjured cells
surrounding it.

During's team said their study indicates their vaccine could prevent
this kind of damage as well.

To test this, they vaccinated rats and induced a stroke. The rats did
have strokes, but the area
damaged was much smaller in the vaccinated rats, they said.

Normally, a vaccine should not be able to get into the brain because of
a system called the
blood-brain barrier that protects from damage caused by the immune

But the researchers noted that sometimes cancer can break down this
barrier, allowing immune
system compounds to cause inflammation of the brain. They think they may
have breached the
blood-brain barrier in the same way, but only temporarily, when they
intentionally damaged the
rats' brains.

The rats were closely watched to ensure the vaccine did not damage their
brain cells in another
way. ``They were completely normal in terms of motor behavior,'' During

``If anything, the rats were a bit smarter,'' he added. But he declined
to go any further, saying that
part of the study had not yet been published.

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13292