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DOES THIS SOUND FAMILIAR - NO MENTION OF VICAL THOUGH
Thursday December 4 5:35 PM EST
Naked DNA Vaccines Combat Diseases
NEW YORK (Reuters) -- Naked DNA may be the wave of the future -- at least when it comes to vaccines. That's right, an
avalanche of new data suggests that immunization with virus genes alone -- without traditional proteins or carrier viruses -- may
be a promising way to combat difficult-to-treat diseases.
"More than a half-dozen vaccines are already in clinical trials against such diverse diseases as AIDS, influenza and cancer, and
work is in progress on everything from rabies and genital herpes to measles, autoimmune diseases and allergies," Gary Taubes
reported in this week's issue of Science.
Such vaccines are simple, containing only a gene plucked from a disease-causing organism and inserted into a circle of bacterial
DNA known as a plasmid. But they seem to work surprisingly well when it comes to eliciting an immune response against
pathogens, at least in animal studies.
For example, a group of researchers at the Naval Medical Research Institute in Bethesda, Maryland were coming up blank in
their search for a malaria vaccine that would protect mice against the disease. Traditional vaccines weren't working, including
those using proteins derived from Plasmodium falciparum, the protozoan that causes malaria. Neither did a combination of P.
falciparum genes and vaccinia virus, a relatively harmless pox virus used in other vaccines.
But a DNA vaccine prompted a "tremendous" immune response that prevented mice from getting the disease, according to
Martha Sedegah, a researcher working on the project.
After encouraging results in monkeys, the vaccine is being tried in 25 human volunteers, Sedegah and colleague Steve Hoffman
told Science. However, other experts in the field recommend cautious optimism.
"I'm concerned about this general perception that DNA vaccines are going to save the world from all the failure of other
vaccines," Rip Ballou told Science. Ballou is a malaria researcher at Walter Reed Army Institute of Research in Rockville,
Maryland.
It is still not clear exactly how the DNA vaccines stimulate an immune response, and the response is still not as strong as that
seen with traditional vaccines. However, researchers are tinkering with different combinations of genes to increase the
response, including plasmids that contain human immune system-stimulating factors.
And it's not clear how safe it is to inject naked DNA into humans. Researchers worry that the gene may incorporate into and
damage human chromosomes -- possibly increasing the risk of cancer. The Food and Drug Administration is concerned that
the vaccines may prompt the body to make anti-DNA antibodies, which are found in people with autoimmune disorders such
as lupus.
"One can be cautiously optimistic, but one still has to be cautious," said Barry Rouse, a viral immunologist at the University of
Tennessee, in an interview with Science. SOURCE: Science (1997;1711-1714) |
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