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Minimor

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The New West Nile Virus DNA Vaccine Explained

by: Stephanie L. Church, News Editor

July 2005 Article # 5940

Commercial vaccines leapt toward state-of-the-art on July 8 when the USDA granted a license for the world's first DNA vaccine for any species. Horses will benefit from this accomplishment that springs from more than four years of collaborative research between Fort Dodge Animal Health and the Centers for Disease Control (CDC). Fort Dodge, CDC, and USDA jointly announced the achievement on July 18. The vaccine should arrive on the market in early 2006.

"This is the first DNA vaccine approved by any regulatory authority in the world for commercial sales rather than just for experimental usage, laboratory studies, and scientific paper publication," says Steve Chu, DVM, PhD, senior vice president of Global Research and Development at Fort Dodge. "This is actually to be used in the commercial setting in the real world."

A veterinary DNA vaccine for salmon gained approval in Canada about a week after the Fort Dodge DNA vaccine.

According to Chu, the collaboration between Fort Dodge and CDC began officially in 2001, but it was brewing shortly after the disease was discovered in the United States. CDC has led the basic research on the initial prototype DNA vaccine, while Fort Dodge has led the DNA vaccine development work and the USDA registration studies.

In a conventional vaccine, killed or weakened viral proteins are put in a product as an antigen, and the animal that receives the vaccine creates an immune response to the protein antigens to become protected. In a DNA vaccine, carefully selected small pieces of the virus' genetic material are given to the animal, and they are taken up by the animal's cells. Inside the cells they are processed into RNA, then into proteins, which are used to stimulate antibodies and a white blood cell immune response.

Four years ago, Chu says DNA vaccine technology was well understood, but it was not yet to a point where it could be clinically applied. Fort Dodge was able to improve the technology in several areas to make the vaccine a reality:

It improved the growth of Escherichia coli bacteria (which has nothing to do with WNV) that hosts the WNV DNA plasmid as it grows. "To prepare the DNA vaccine, we cannot just grow the WNV DNA plasmid by itself (it will not replicate by itself in the laboratory setting), it needs some host to carry this DNA material," explains Chu. "The host in this case is E. coli."

It improved the extraction of the WNV DNA material from the E. coli.

It mastered the purification of the WNV DNA (after removal from the E. coli), and invented some creative ways to protect the WNV DNA during the production process.

It enhanced the stability of the WNV DNA material.

It developed a formulation for the DNA vaccine that improves the DNA delivery as well as enhances the vaccine's ability to produce an immune response in the horse.

"After we've worked for so long on this, my feeling is that the development from the original research materials into a final product is partially science, and partially art," says Chu.

To be licensed by the USDA, the product had to be proven as pure, safe, potent, and efficacious. Specific information on the vaccine trials will be released when the vaccine goes on the market in early 2006. Scientists presented preliminary results in abstract form at the 85th Annual Meeting of the Conference of Research Workers in Animal Disease in November 2004, which was held in Chicago, Ill. This study showed the DNA vaccine was capable of inducing an immune response to the WNV in horses.

The vaccine will be marketed as an additional tool in the Fort Dodge WNV vaccine line rather than a replacement for WNV Innovator or the WNV combination vaccines. When the DNA vaccine hits the market, veterinarians will be able to contact Fort Dodge for technical advice.

CDC Director Julie Gerberding, MD, MPH, says the breakthrough vaccine "has potential benefits far beyond preventing WNV in horses. This science will allow for the development of safer and more effective human and animal vaccines more quickly." Chu said the CDC is currently leading a clinical trial to determine if the vaccine technology can be used in humans.

"Four or five years ago, it was a challenge to try and make the DNA vaccine feasible for commercial use," Chu reflects. "We're certainly happy to see that we've accomplished a very enormous mission, but our mission has not ended here--we will continue to work on the vaccine technology as a whole, furthering the knowledge and availability of even better products for the veterinary community."

Readers are cautioned to seek the advice of a qualified veterinarian

before proceeding with any diagnosis, treatment, or therapy.
 

Becky

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Yes, I read about that new vaccine. Sounds exciting to me! A DNA based vaccine should be very effective.
 

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