New techniques that can produce "buckets full" of monoclonal antibodies outside animals' bodies has led to the development of a vaccine to prevent a disease that is having a major impact on Utah's sheep industry.
Using biotechnology, more commonly called genetic engineering, to develop a veterinary vaccine to eliminate epididymitis, a disease that creates reproductive problems in male sheep, is one of many such projects in process at Utah State University.Mark C. Healey, a professor in the department of animal, dairy and veterinary sciences, said his project centers on using biotechnology techniques to produce monoclonal antibodies that allow isolation of specific proteins needed for the vaccine.
While the process does not involve actual genetic alteration, it does allow test-tube production of proteins formerly available only from living animals. Healey said the old process made development of a vaccine for epididymitis both time consuming and expensive.
Epididymitis has a direct monetary impact on Utah sheep production, Healey said. Some estimates put the losses at close to $1 million annually.
The disease affects virgin male lambs and their reproductive hormones. Because the lambs are intended as breeding animals, their value is severely affected if they contract the disease. Also, the appearance of the disease in a breeding line can affect breeders' future sales.
In 1975, Healey said, a team of scientists developed a technique to produce the needed monoclonal antibodies in a test tube. That work resulted in a 1984 Nobel prize for the developers. This was a great leap forward, said Healey, because it allowed the antibodies to be produced in large quantities outside the body. For the USU project this is important because the antibodies are needed to develop the proteins from which Healey's team created the epididymitis vaccine.
"By being able to grow the antibodies outside of the animal body we can develop unlimited supplies," Healey said. "This gives us a much-needed tool in developing the vaccine."
Also, the work can take a more narrow focus. In the past, said Healey, vaccines have been prepared from whole, weakened or killed bacterial cells.
"In recent years, the effectiveness of whole-cell bacterial vaccines has been questioned," he said. "Biotechnology has taught us that the vast majority of the cell has nothing to do withimmunity protection responsibility."
Now, the focus is on using the monoclonal antibodies to help identify those parts of the cell that might be useful in developing vaccines. Some recently developed vaccines are using only a small fraction of the cell. These are called subunit vaccines.
Healey said his effort involved identifying the protective antigens (substances that bring about an immune response) on the surface of the two bacteria that appear to cause the disease. Once those antigens were identified, they were isolated and purified for use in a subunit vaccine.
"The monoclonal antibodies allow us to look at the cell and determine which portions are the best candidates for use," Healey said. Healey described the process as similar to skinning a grape. He said the biotechnology approach allows researchers to skin the cell and get rid of the interior, which is not needed in the process. The researchers then take the cell skin where the protective antigens reside and look for things that may prove helpful.
And the cost factor in developing the vaccine is greatly reduced. Healey said the bottom line for sheep ranchers, as in most business enterprises, is cost.
"If the cost is too high, the ranchers won't use it," Healey said. "They'll take their chances the way they are presently doing."
Healey said a patent is pending on the vaccine. The vaccine has shown encouraging results in field trials the past two years. Recently a marketing agreement was signed with ImmunoVet Inc., Tampa, Fla., to produce and distribute the vaccine. Developers hope to see the product on the market in early 1989.