Dow AgroSciences seeks better vaccine: Plant-based preventive measure loaded with potential

July 17, 2006

Imagine a vaccine that kills salmonella bacteria in chickens long before they reach the food-processing center, possibly reducing the chance of a food-borne illness landing on your dinner plate.

That's one of the possibilities researchers are thinking about on the northwest side of Indianapolis, where Dow AgroSciences has become a pioneer in the new frontier of plant-based vaccines.

Earlier this year, the subsidiary of Dow Chemical Co. received the world's first regulatory approval for a plant-made vaccine from the U.S. Department of Agriculture Center for Veterinary Biologics.

The approval gave Dow AgroSciences a road map for what company officials hope will be a long journey into a new world of vaccines that may hold up better and pack a bigger punch than current products. The company plans to develop products for the $3.5 billion animal health vaccine market, but also is thinking bigger.

"The exciting thing about this is if we can get it to work in animals, it may well work as a good model for human application somewhere down the road as well," said Butch Mercer, Dow AgroSciences global business leader for animal health and food safety.

Mercer said it was way too early to gauge how these new vaccines might affect job growth at the company's Indianapolis location, where it employs about 1,100 people. He noted that "the evolution of the technology will really be the driver to all that."

However, the potential of the vaccines already has stirred some excitement in different corners of the Indiana life sci- ences community.

A better mouse trap

Most vaccines are produced in a mammalian or microbial cell culture such as yeast. For instance, some human vaccines are produced in highly specialized, pathogen-free chicken eggs.

A live virus is grown in the eggs, harvested, killed and then formulated into the vaccine. Sometimes, however, the process isn't that clean. Chicken eggs also can produce blood that may be harvested with the virus and pass along another viral or bacterial contaminants.

This happens "quite routinely," Mercer said, noting that contamination triggered the flu-vaccine shortage that cropped up a couple of years ago.

These vaccines also don't stick around long. They need refrigeration, and some can deteriorate or start to lose effectiveness within a matter of hours, Mercer said.

Better living through plants

Vaccines developed through plants can avoid many of these hitches. In that method, scientists insert only a piece of the antigen-the immune-stimulating portion of the disease that they want-into a plant cell.

The plant cell is then allowed to go forth and multiply in a bioreactor. Think microbreweries.

"What we've really tried to explain to people is that they're just big stainless steel tanks," Mercer said.

The end product comes from a simpler production process, is more stable, can last longer and doesn't bring with it animal contaminants. The plant-made vaccines haven't even triggered allergies in animals, although Mercer said they don't know whether they will in humans.

"We're extremely excited about the safety of what we've seen in these proteins when they're administered to animals," he said. "They're very, very safe."

They're also very, very new. Mercer cautioned that there is still much to be understood about these vaccines.

"There hasn't been a lot of scientific work done in this field," he said.

Indianapolis hosts the Dow Agro-Sciences headquarters and the company's largest research and development center, but plant-based vaccine development was not contained here.

The original patent for the concept dates back to 1989, when it was given to researchers at Washington University in St. Louis and Mycogen Corp. Dow bought Mycogen nearly 10 years later and started research on plant-based vaccines in 2001.

The research involved collaborations with several partners, including Boyce Thompson Institute in Ithaca, N.Y., and Arizona State University, Mercer said.

A Nebraska-based contract research organization, Benchmark Biolabs, also helped, and it will manufacture sample vaccination batches.

A positive reception

Purdue University professor Harm HogenEsch has already talked with Dow AgroSciences about a possible research collaboration. He's intrigued by the potential potency in a plant-made vaccine.

He noted that some diseases require as many as three injections to build proper immunity. A more potent vaccine could trim that number and save money.

"You have to think about the poultry or swine industry, where you have hundreds or thousands of animals that need to be immunized," said the head of Purdue's Department of Veterinary Pathobiology. "A single vaccine would be a tremendous cost savings."

He also noted that the pharmaceutical industry has taken a renewed interest in vaccines, and such products are desperately needed to treat afflictions like tuberculosis or AIDS.

"I think this plant cell technology has real potential," he said.

Baker & Daniels attorney Pat Cross isn't as familiar with the technology. But he knows the local life sciences scene, and he said the potential behind this vaccine extends beyond the patients or animals it might treat.

It could add to the number of people who do life sciences work in Indianapolis. It also could enhance the region's reputation. That, in turn, could snowball and help attract venture capitalists, executive talent or researchers for places like the IU School of Medicine.

"They want to go somewhere knowing that if this particular venture doesn't suc- ceed, that there's a community with more companies coming online and thus more employment opportunities," said the chairman of Baker & Daniels' life sciences practice.

Taking the next steps

No other companies have applied to produce plant-based vaccines for animal health, according to Suzan Holl, a spokeswoman for the USDA's Center for Veterinary Biologics.

The USDA approval that Dow received in late January covered a vaccine to treat a common poultry disease. The company won't market that vaccine in the United States, but it has many other opportunities it plans to explore.

Avian flu, canine diabetes and West Nile virus for horses are some of the vaccines researchers hope to tackle, Mercer said. Then there's the food-safety program, which would address salmonella.

"That's a very-early-stage program, but it's an exciting concept," he said.

Dow AgroSciences, which does business in more than 50 countries, notched $3.5 billion in sales last year. Its leaders hope eventually to rack up $500 million or more in new sales each year, and they point to plant-made vaccines as one of the platforms that can take them there.

As Mercer noted, vaccinations are one of the fastest-growing segments in animal health and should be for years to come.

"Prevention is a lot cheaper than treatment," he said. "Whether it's animal or human, that's true across the board."
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