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Genetics Issue : Feud Marks Success of Pig Vaccine

Times Science Writer

Past Interstate 74 and across the train tracks just east of town here sits a little blue building that used to be the Blue Angel bar, once “the hottest spot in town,” according to local residents. The building is no longer a bar, but it is still very much a hot spot.

It is the office of veterinarian Roger Saline, the first person authorized by the federal government to release a genetically engineered microorganism into the environment.

What Saline did on Oct. 9 was vaccinate a batch of piglets on Kevin Main’s nearby farm with a genetically engineered vaccine designed to prevent pseudorabies, a disease that is costing the pork industry as much as $60 million a year.

Use Went Unnoticed

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That initial vaccination and the subsequent use of the vaccine by Saline and other veterinarians went unnoticed until April 3 when news organizations disclosed Saline’s work, touching off a firestorm in Washington that forced the U. S. Department of Agriculture to suspend marketing of the vaccine until an environmental impact statement could be prepared.

The controversy has all but obscured the vaccine’s apparent effectiveness.

And even though administrator Bert W. Hawkins of USDA’s Animal and Plant Health Inspection Service last week authorized the resumption of the vaccine sales, activists who oppose genetic engineering immediately filed suit seeking to reinstate the suspension.

Furthermore, the legality of the original licensing procedure and the subsequent suspension are expected to be examined today at a hearing conducted in Washington by Rep. Harold Volkmer (D-Mo.), chairman of the subcommittee on investigations of the House Committee on Science and Technology.

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Uproar a Mystery to Some

Here in the heartlands, however, the people most affected by the new, genetically engineered vaccine wonder what all the uproar is about.

“If there’s an effective product, and it’s gonna do the job,” Main said, “we’ll use it.”

Many other swine producers in the Midwest also are clamoring for the new vaccine. Roughly 10% of the nation’s swine are infected with pseudorabies.

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The unprepossessing, sparsely furnished building that is Saline’s office is marked only by a black-on-white sign announcing Swinemap, Inc. (The “map” is for “managing pigs aggressively.”)

Inside sits an antique soda machine with a hand-lettered sign: “Sodas 25 cents, 15 cents more if you take the bottle with you.”

To the right is a metal bookshelf with 10 stacks of journals about the care of hogs, the feeding of hogs, the health of hogs, and the breed ing of hogs, everything one might ever want to know about hogs. In the middle of the journals is a stack of back issues of Personal Computing--the first hint that Saline is no ordinary country vet.

On his desk is a computer printout listing the results obtained with the new vaccine--a printout prepared in the back room on an IBM PC-XT.

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“We’re not traditional veterinarians, we’re more consultants than doctors,” the 27-year-old vet said with a slight Midwest twang that points to the fact that he was born and raised on a farm right outside Galesburg. Saline graduated from the nearby School of Veterinary Medicine at the University of Illinois at Champaign-Urbana in 1984.

Swinemap’s business is devoted almost exclusively to pigs, making it one of only a handful of “sole-swine practitioners” in the country. And even so there are limits to what Swinemap will do even for pigs.

“I’m not a very good surgeon,” Saline said. “People don’t call me to come out and pull pigs (help them give birth). They do that themselves. What they want from us, primarily, is diagnostics and economics.” Saline diagnoses diseases, treats them, and recommends feeding programs and vaccinations, among other tasks.

“We use the computer a lot because when we recommend a course of action, we have to prove to them in figures that it’s cost effective.”

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Cost-effectiveness is important because swine breeders operate on the edge of profitability. On the best farms, a sow usually has a litter of 10 or 11 piglets every 143 days. That’s 115 days for gestation, 21 days for nursing the piglets, and roughly 7 days thereafter until she is fertile and ready to be bred again.

Sows are usually used only for about six or seven litters. After that, the litters get smaller and the piglets are not as healthy. It normally costs about $34 to $35 to raise a piglet until it weighs 40 pounds, the point at which it is sold--currently for about $37--to a feedlot operator for fattening. They are kept at the feedlot until they reach a market weight of about 220 pounds. They are then sold for about 40 cents per pound.

Swinemap manages swine herds in an area that stretches a couple of hundred miles in each direction from company offices. Saline’s senior partner, Michael Schwochert, even flies to Mexico periodically to consult for swine breeders there. Their work, furthermore, is not particularly easy because piglets are surprisingly fragile creatures.

They manage 2,600 sows that produce 45,000 to 50,000 piglets a year.

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“Pigs are born weak and small,” Saline said. “They have little bodyfat, so they get cold easily and can readily deplete their energy reserves. If they are stressed, they get sick easily. On a normal farm, we expect 10% to 20% of every litter to die, half within the first 3 days and the rest within 3 weeks.”

Squashing Causes Death

The leading cause of death among piglets is squashing, which occurs when the sow flops down on her side without looking first and crushes a piglet. These are called “laid-ons.”

Piglets are afflicted with many diseases, but one of the most severe is pseudorabies, occasionally called “the mad itch.” It is caused by a type of herpesvirus, and is characterized by intense skin irritation and sores. In weak piglets, it can cause death within 48 hours.

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In healthier pigs, the virus stays hidden in the central nervous system for months or even years before suddenly reproducing rapidly and infecting other pigs. It can also spread to sheep, cattle, and household pets, although not to people.

An anti-pseudorabies vaccine is already on the market, produced by Norden Laboratories. The vaccine is made from a weakened form of the herpesvirus that was obtained by growing the virus in chick cells for thousands of generations, a process that is used in preparing most conventional vaccines.

But the Norden vaccine is not as effective as had been hoped, and there is some evidence that the weakened virus can be harmful to other livestock.

More recently, using genetic engineering techniques, biochemical virologist Saul Kit of Baylor University produced what many scientists believe to be a better vaccine.

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Removed Herpesvirus

He identified and then removed a gene that enabled the weakened herpesvirus to infect other livestock. After vaccination, the engineered virus invades the central nervous system, but it does not produce pseudorabies and it cannot get back out of the nervous system to spread to other animals.

Once the engineered virus is ensconced in the pig’s nervous system, furthermore, its more virulent progenitor can no longer get in.

The vaccine itself was perfected by Kit’s company, Novagene Inc., and licensed to Biologics Corp. of Omaha. Biologics has produced 2 million doses of the vaccine, called Omnivac-PRV, and has already sold about 10% of the doses, worth about $250,000, since USDA approved the vaccine.

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Biologics came to Saline for help in testing the vaccine because of his specialized knowledge of pigs, his access to herds, and his past experience in testing veterinary products. “Before we started the work, several people from Biologics came here, Saul Kit came up, and we brought the state vet in and talked about the vaccine and the trials,” Saline recalled.

He harbored few doubts about the new vaccine to begin with, and by the time the discussions were over, “I felt it was totally safe. They knew exactly what they were doing.”

In October, with no fanfare, USDA gave Biologics permission to field-test the vaccine. Last year, the U. S. Environmental Protection Agency had given similar permission to Advance Genetic Sciences of Oakland to field-test a genetically engineered, frost-preventing bacterium on strawberry plants. But that permission was withdrawn after it was disclosed that the company had injected the bacterium into trees on its rooftop. The test also had been blocked by a lawsuit and by the Monterey County supervisors.

Saline initially vaccinated 500 of Main’s piglets with the vaccine to check for safety. Only six of them died, and none of the deaths could be linked to the vaccine.

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He then vaccinated 1,000 sows owned by Main and others and compared them to a control group of sows that were unvaccinated. None of the piglets from vaccinated sows contracted pseudorabies. Similar tests were carried out by vets in three other states, with equivalent results.

Main was happy to have the trials conducted on his farm because a pseudorabies epidemic had recently devastated his herd, killing a third of his 300 piglets. If he had not been able to use the vaccine, he would have had to empty his nursing facility and disinfect it completely, a task that is expensive and not always completely effective.

Since the trials of Omnivac, Saline has not used the vaccine very much “because we haven’t needed it.” Other vets are more eager to use it, however, because pseudorabies has become a serious problem.

According to veterinarian Leroy Schnurrenberger of USDA, studies in 1974 showed that only one pig in 200 exhibited evidence of exposure to pseudorabies. By 1984, that figure had grown to one in 10.

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Quarantined Last Year

In Minnesota, according to veterinarian W. J. Mackey of the Minnesota Board of Animal Health, 145 swine herds were quarantined last year because they had been infected with pseudorabies. “We’re losing $1 million a month because of this disease,” he said. “We need protection for 20,000 swine herds.”

Officials in Nebraska are also very interested because as many as 20% of the state’s swine herds are affected by the virus.

Despite the controversy about the licensing of the vaccine by USDA, according to Orville Bentley, assistant secretary of agriculture for science and education, “No one has really raised serious questions about the safety of this product.” Instead, the battle has been prompted by other issues.

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Within USDA itself, there has been a continuing turf battle between the regulatory and the scientific sides of the department over which should be involved in licensing decisions--a situation that is likely to be explored today in Washington.

In the case of Omnivac, regulatory officials licensed the vaccine with little or no input from the scientific staff, and the scientists have spoken out with a vengeance.

The split within USDA is “about as blatant a turf battle as I’ve seen in an agency,” according to Jeremy Rifkin, the strongest opponent of genetic engineering and founder, head, and virtually the entire staff of the Washington-based Foundation on Economic Trends.

USDA “has run roughshod” over its own rules in licensing the product, he said. Rifkin has not argued that the vaccine is unsafe, although he has filed suit in federal court in Washington to block its sale.

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Saline, meanwhile, is looking forward to more products from the biotechnology industry. Pigs, he says, contract many other diseases for which there are no effective preventive agents or treatments.

“I think biotechnology will give us answers to all of these things.”


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