An international
collaboration of scientists has demonstrated the promise of gene
therapy for combating hepatitis C infections, which affect about 200
million people worldwide. Currently, the protein alpha interferon is
the only approved therapeutic for treating hepatitis C infection and
in many cases it shows only limited effectiveness. Reporting in the
May issue of
Nature Biotechnology, scientists demonstrate that adenoviral
gene therapy can lead to significant reductions in levels of
hepatitis C virus in mice containing virally infected human liver
cells.
As hepatitis C lurks within human liver cells, the authors
designed their strategy to specifically induce death in those cells
harboring the virus, with the hope that this would prevent
production of new infectious virus. To accomplish their goal, they
turned to a cellular protein called the BID precursor
(BH3-interacting domain death agonist precursor), which triggers the
killing of cells only when degraded by enzymes called proteases.
Because BID precursor is not normally degraded in healthy cells or
cells infected with hepatitis C virus, the researchers engineer into
BID precursor a recognition site for a protease found in hepatitis C
virus. In this way, they hoped that hepatitis Cinfected cells
exposed to the modified BID molecules would be specifically targeted
and killed.
Sure enough, when the authors used adenoviruses to deliver the
gene for the modified BID precursor into human liver cells implanted
in mice, they found that BID was cleaved only in those cells
infected by the hepatitis C virus and expressing the viral protease.
In infected cells, BID went on to cause cell death, effectively
halting progression of hepatitis infection. In the majority of
cases, BID gene therapy resulted in substantial decreases in the
quantity of virus; in mild infections, the clearance of virus was
complete. The authors approach holds promise as a therapeutic
option for hepatitis C as well as for other types of viral
infections.
Author contact:
Christopher D. Richardson
Ontario Cancer Institute, Toronto, Ontario, Canada
Tel: +1 416 204 2280; E-mail: chrisr@uhnres.utoronto.ca
ALL INFORMATION, DATA, AND
MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION
PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS
OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR
LEGAL ADVICE. THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND
COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH
YOUR HEALTH CARE PROVIDER.
"A foolish faith in authority is the worst enemy of truth."
-- Albert Einstein, letter to a friend, 1901
"I know of no safe depository of the ultimate powers of the society but the people themselves, and if we think them not enlightened enough to exercise control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education."
-- Thomas Jefferson, letter to William C. Jarvis, September 28, 1820
"What's the point of vaccination if it doesn't protect you from the unvaccinated?"
-- Sandy Gottstein
"Who gets to decide what the greater good is and how many will be sacrificed to it?"