A NEW WAY TO PREVENT DISEASE
By Sean Henahan, Access Excellence
Genomic vaccination appears to offer promise as a prevention of
diseases caused by viruses or bacteria, suggest animal studies
carried out at the University of Texas.
"Genetic immunization is going to be a revolution in vaccines
and now we've taken it to another level - genomic vaccination.
We should be able to apply this technology to any pathogen,"
said Dr. Stephen Johnston, professor of internal medicine and
biochemistry, UT Southwestern Medical Center, Dallas.
Johnston and colleagues have completed research in which mice
were protected from mycoplasma infection - a tuberculosis-like
disease - after getting a "genomic vaccine.". The researchers
made the vaccine by cutting up the genome of mycoplasma into
small bits and shooting all the genomic bits into the skin cells
of the mice. Each bit of mycoplasma DNA made a mycoplasma
protein, which produced an immune response in each mouse.
"This genomic vaccine fools the immune system into thinking it
has been infected by the real pathogen. Protection is produced
without risk of infection, and it may be more effective than
conventional vaccines," said Johnston.
Johnston, holder of the Dr. Eugene Tragus Chair in Molecular
Cardiology, was the first to demonstrate genetic immunization in
1992, with the development of a "gene gun," which proved
DNA-coated microprojectiles shot directly into the cells of
animals could provoke an immune response. Since then, genetic
immunization research has advanced and is being applied to many
diseases, including the human immunodeficiency virus (HIV).
While conventional vaccines have been able to eradicate polio
and prevent diseases like measles, mumps and rubella, they do
have disadvantages. Because weakened pathogens are injected,
there is a risk of developing the disease. For example, in 1955
some people given the new polio vaccine contracted polio from
the immunization. Conventional vaccines are also fairly costly
to produce and require cold storage - making them unavailable to
developing countries where they are often needed most.
"Vaccines are the most cost-effective way to save human lives,
but we don't have them for most major diseases in the world,"
The breakthroughs in genetic immunization pioneered by Johnston
with his gene gun require identifying the precise gene that
could provide immunity. Johnston's new genomic approach does not
require isolating the specific gene; it only requires the much
simpler task of finding the complete genome structure.
"It's all pretty simple," he said. "We'd been working on genetic
vaccines for five years before it dawned on us. It came to me in
a flash, and we started working on it the next day."
Johnston tapped into robotics technology developed by UT
Southwestern's Human Genome Project researchers to make the
mycoplasma vaccine quickly.
"We're talking months to develop a vaccine, whereas people have
been working for years trying to get vaccines - 12 years for
HIV," he said.
The high-speed technology could prove to be invaluable in
confronting the growing number of emerging infectious diseases.
Animal, and possibly human, applications may be available in a
The current research appeared in the Oct. 19, '95, issue of
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