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GENOMIC VACCINES:
A NEW WAY TO PREVENT DISEASE

By Sean Henahan, Access Excellence


DALLAS- 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," Johnston said.

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 few years.

The current research appeared in the Oct. 19, '95, issue of Nature.


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