'Superdrug' Against Range of Viruses Shows Promise in Animal Trials 08/11/11
THURSDAY, Aug. 11 (HealthDay News) -- A potentially
groundbreaking drug appears effective against a wide range of viral
infections, including the common cold, flu, stomach viruses, polio
and dengue fever -- at least in mice.
The new drug is made from living cell's own defense systems and
works by targeting a type of genetic material found only in those
cells infected by viruses, MIT researchers explained.
"Currently there are very few antiviral treatments, and most that do exist are highly specific for individual viruses or have undesirable side effects," noted lead researcher Todd Rider, a senior staff scientist at Lincoln Laboratory's Chemical, Biological, and Nanoscale Technologies Group, which is part of MIT.
The new drug is called DRACO (from the more unwieldy
"double-stranded RNA activated caspase oligomerizers"). According
to Rider, it "has the potential to safely treat or prevent a broad
spectrum of viral infections."
Still, a long road awaits before humans might benefit, if ever.
Clinical trials remain years away and any drug available to
patients might not materialize for a decade, Rider said.
The report was published recently in the online journal
As the researchers explain, DRACO targets a kind of genetic
material known as RNA.
When any virus infects a cell it starts making more copies of
itself. During this process, viruses produce strings of
double-stranded RNA (dsRNA). These strings are not normally found
in healthy human or animal cells, the researchers noted.
As part of their natural defense against infection, cells also
make proteins that attach to dsRNA -- helping to prevent the virus
from replicating. Many viruses escape harm by blocking this
cellular defense strategy, however.
DRACO includes a so-called "delivery tag," that allows it to
cross cellular membranes and enter any human or animal cell that
contains viral dsRNA.
Rider's idea was to combine a dsRNA protein that attaches to
cells with another protein that causes cells to die. That means
that when DRACO hooks up with the suspect dsRNA, it kickstarts a
process whereby the infected cells begin to kill themselves.
On the other hand, if the RNA the drug has targeted is
not in the cell (ie, a healthy, uninfected cell) then DRACO
leaves that cell alone, Rider explained.
To see if this approach would work, the MIT team tested out the
drug on both human and animal cells made in the lab. In addition,
they tested their concept in mice infected with influenza. Mice
treated with DRACO were cured of the flu, without any adverse
effects, Rider said.
"So far, we have not found any side effects in cells or in mice," Rider said. "The mice appeared normal all the time they were alive, and their organs appeared normal when they were examined subsequently," he said.
In addition, he said that they also demonstrated that DRACO is
nontoxic in 11 different cell types representing different species
including humans, monkeys and mice, and in organ types such as the
heart, lung, liver and kidney.
Rider believes that DRACO has the potential to "revolutionize"
the treatment and prevention of virtually all viral diseases,
including everything from the common cold to Ebola. "Because the
antiviral activity of DRACO is so broad-spectrum, we hope that it
will even be useful against outbreaks of previously unknown
viruses, such as the 2003 SARS outbreak."
"We are currently testing additional viruses in mice and beginning to get promising results with those, too," he added.
Still, don't look for DRACO in your medicine cabinet anytime
"We are hoping to license this technology to a pharmaceutical company that can carry it through larger animal trials and human clinical trials. Realistically, it will probably be at least a decade before you can buy DRACO at the drug store." Rider said.
Mario Stevenson, a professor of medicine and chief of the
division of infectious diseases at the University of Miami Miller
School of Medicine agreed that the approach is innovative. "But
there is a big difference in administering a protein to mice and
doing the same protein in humans," he said. "We have learned the
hard way that in going from mice to men there are many hurdles to
In addition, making these proteins is very expensive. That could
make any drug out of reach for use in developing countries, where
many deadly viruses -- such as dengue fever and Ebola -- are
endemic and for which there are no current treatments, Stevenson
Stevenson is also concerned that there may be adverse affects in
human not yet anticipated or seen in mice or even in human cells.
"This happens with a lot of proteins introduced into the
circulation," he said.
However, if all the problems can be overcome, then "it could be
incredibility important," he added.
For more information on viruses, visit the
U.S. National Library of Medicine.
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