An End to Herpes -- and HIV?
April 20, 2000 -- A new way to fight viruses might mean new treatments for
herpes, and maybe even AIDS. In a study reported at a scientific meeting,
researchers today said that members of a new class of drugs -- some of which
already are known to be safe in humans -- might stop many major viruses dead in
"This is a completely new approach," study leader Priscilla A.
Schaffer, PhD, tells WebMD. "All of the existing antiviral drugs target the
virus. But viruses don't grow in a vacuum, they grow in a cell. The cell
provides the virus with lots of [things] it needs to grow." The new
treatments would take these things away, leaving the virus high and dry like a
seed without water.
In order for viruses to reproduce, they must use a human substance known as
"cdk." Cdk works like a little motor that drives the cell through the
process of division. The new drugs throw a monkey wrench into the cdk
machinery. When tested against herpes viruses in the test tube, they worked so
well that the virus could not make any copies of itself.
Perhaps the most exciting thing about the research is the suggestion that
drugs that block cdk might be effective not only against all human herpes
viruses, but also against hepatitis viruses and even HIV.
"The potentially exciting thing about this class of compounds is the
spectrum of viruses likely to be affected," says Schaffer. "Our best
guess is all the herpes viruses ... will be shown to be inhibited." But
more importantly, many human viruses, including HIV, are likely to be inhibited
by these drugs, he says. "While one can say this is an early stage of the
research, the likelihood is great that other viruses will be affected," he
adds. Schaffer is chair of the microbiology department at the University of
Pennsylvania School of Medicine.
The cdk motor goes out of control in some cancers. Because of this, many
drug companies are working to develop anti-cdk drugs. One of these drugs
already is being studied at the National Cancer Institute (NCI) -- and the
trials already have answered one major question.
"We are very confident that we can give it safely to humans," NCI
researcher Edward A. Sausville, MD, PhD, tells WebMD. "The major side
effects are related to diarrhea." That is one of the reasons drug companies
are looking at other drugs to block cdk -- drugs that might not have this
unpleasant side effect, he says.
Sausville says that anti-cdk drugs will still have to undergo full safety
tests before they can be used against virus infections. Although previous
studies in cancer patients have shown that the drugs that block cdk appear to
be safe in humans, the drugs in development to fight viruses are slightly
different, he says. Therefore, the drugs still need to be closely scrutinized,
but Sausville is encouraged that this new research will speed things along.
Sausville is an associate director of the NCI's developmental therapeutics
It will also be of great interest to show exactly which of the cdks must be
blocked in order to stop these viruses from causing disease, University of Iowa
biochemist David H. Price, PhD, tells WebMD. Price and co-workers are currently
developing drugs similar to cdk blockers to fight HIV.