The worldwide elimination of all types of the costly foot-and-mouth disease that is fatal to many meat-producing animals such as cattle, sheep and pigs "is our goal and what we expect to do," a biochemist who helped develop a gene-engineered vaccine for it said yesterday.
Dr. Howard L. Bachrach, the leader of the Agriculture Department team that developed the vaccine through gene-splicing, said it is the first such vaccine to be applied successfully to any human or animal disease.
A safer and more effective vaccine than existing ones, it also is a significant step toward eradicating a disease that afflicts about 30 species of animals in scores of countries.
This success is expected to be the opening gun in the race to produce new vaccines, which can be made by the same method, for a large number of animal and human disease viruses, including hepatitis and rabies.
Bachrach proved six years ago that such a new and more useful vaccine could be made. With the product in hand, the Agriculture Department maintains that the vaccine could save billions of dollars annually in world agriculture and substantially increase the world's meat production.
The Agriculture Department has done research on the disease for 28 years, but only when recombinant DNA technology was invented did this kind of sudden, large advance become possible.
A severe and highly contagious disease, foot-and-mouth affects such cloven-hoofed animals as cattle, sheep, pigs and goats. When infected with the tiny virus that causes foot-and-mouth, the animals quickly develop blisters inside their mouths, on their noses and around the top of their hoofs.
Though less than 5 percent of the afflicted die, most animals affected become thin, weak and unable to produce milk or quality meat. There is no foot-and-mouth disease in North America, and the United States refuses to import meat from countries where it exists.
Vaccines exist for the disease, but they are expensive, delicate and dangerous, said Dr. Jerry Callis, director of the Plum Island research center where the new vaccine was successfully tested.
The standard vaccines must be constantly refrigerated, not a small matter in underdeveloped countries. The vaccine is also volatile enough to be a major source of the disease it is trying to prevent.
Killed foot-and-mouth viruses are used to make the vaccines, and sometimes they escape from the laboratory making them. Sometimes a few live germs get into the vaccine, and when injected into animals they will cause the disease instead of preventing it.
"In the last six weeks in Europe alone, there have been outbreaks in Austria, France, the Isle of Jersey, Greece, and Italy," Callsi said. The outbreak in Italy was caused by live viruses getting into the vaccine, he said. South America, Europe, Africa, and Asia all are "infected."
The new vaccine was created by the Agriculture Department and the genesplicing firm of Genentech. According to Callis, it needs no refrigeration, can be produced cheaply and can never cause the disease it is intended to prevent.
Unlike those in use, which use whole, dead viruses to make up the vaccine, this new vaccine comprises a single protein called VP3. This protein is taken from the surface of the virus, and is the element that activates the disease-fighting system of the animal.
The protein triggers the body's chemical defense against one specific disease virus, in this case one of the two dozen important varieties of foot-and-mouth disease.
The new vaccine is produced by taking the animal gene responsible for manufacturing the key protein, and transplanting that gene into another organism, a bacterium. The bacterium acts a a factory to produce the foreign protein. When raised in large quantities, the bacteria will be able to easily make large quantities of the desired immune protein.
Genentech legally owns the organism that makes the new vaccine, and the U.S. government will have the rights to use it, royalty free.