New
compounds help some control infection. Scientists also
get clues into how virus works.
From
Reuters
WASHINGTON – New experimental compounds may be
able to help the body fight off hepatitis C –
an incurable virus that infects millions around the
world and causes liver failure and cancer, researchers
said Thursday.
The research, done by separate teams in Canada and
the United States, also led to discoveries about how
hepatitis infects the body – and how the body
fights of infection.
Hepatitis C was identified only in 1989.
It is spread through blood transfusions and the reuse
of needles – including those used for drugs and
tattoos.
It infects about 175 million people around the world,
including about 4 million in the United States. And
many of its sufferers do not know they are even infected.
About 8,000 die every year of hepatitis C in the United
States alone.
Viruses such as influenza are eventually cleared by
the immune system.
But hepatitis C can stay in the body forever, eluding
the various weapons of the immune system.
The national Centers for Disease Control and prevention
in Atlanta says that 75% to 85% of those infected have
chronic, or permanent, hepatitis C infection.
Seventy percent of these will develop liver damage
leading to cirrhosis and liver cancer.
An antiviral drug called ribavirin, used along with
an immune system booster called alpha interferon, can
help some patients control hepatitis C infection, but
it does not cure it.
“Just a year ago, the hepatitis C virus field
had no leads,” said Michael Gale, |
a virologist at the University of Texas Southwestern
Medical center in Dallas who led one of the studies.
“We were totally clueless.”
Gale’s team and a team led by John Hiscott at
McGill University in Montreal found out how the virus
deactivates a cell’s defenses, so it can stay
in the cell virtually forever.
Writing in the journal Science, both teams said they
found that the virus can block a cell’s production
of interferon regulatory factor 3 or IRF3 – produced
by cells to defend against infection and call in more
immune system help.
The McGill team found it blocks a second compound called
IRF-7.
“This really gives us the first evidence of how
it is the that the virus can cause lifetime infection,
as opposed to influenza, which infects you for a week,”
Gale said in a telephone interview.
Gale’s team also discovered that individual cells
have their own immune responses, a finding that his
team has published in the April issue of the Journal
of Virology.
“The whole thing works by IRF3 turning on genes
in the human cell that fight off infection. We are going
to find out what those genes are, what their products
are,” Gale said.
This in turn could lead to new ways to battle a number
of different viruses, from the AIDS virus to herpes.
In the meantime, two drug companies – Schering-Plough
and the privately owned German company Boehringer Ingelheim
– have developed compounds that they hope will
work against hepatitis C.
The work reported in Science was all done in the laboratory,
and Gale said the drugs will be difficult to test because
no animals are naturally infected with hepatitis C the
way humans are. |