By Chris Bowman
James Murray knows his experiments with human genes and goats give
some people the creeps.
Crossing anything human with four-legged hoofers evokes images of
mythical half-man, half-animal centaurs from ancient Greece.

In reality, genetically altered goats look and behave no differently
from regular ones - both are just as eager to gnaw Murray's sleeves and
untie his shoes at the goat barn.

"Could you get your grubby paws off?" the University of
California-Davis professor asked of his inquisitive test subjects during a
recent tour.

Murray and fellow animal scientist Elizabeth Maga engineered a small
herd of Alpine and Toggenburg dairy goats to produce high levels of a human
antibiotic-like protein in their milk.

Just as mother's milk helps protect infants from germs, the
researchers figured, humanized goat's or cow's milk would better defend
dairy animals and their offspring from illness. Germ-fighting milk might
also slow spoilage, prolonging the shelf life of dairy products.

The scientists' ultimate question, though, is a humanitarian one:

Could the same procedure produce fortified powdered milk and,
eventually, genetically modified goat herds for poor regions of the world?

The beneficial protein, lysozyme, destroys bacteria that cause
intestinal infections and diarrhea, which every year claim more than 2
million impoverished young lives. That's a toll among children under age 5
higher than from AIDS, tuberculosis and malaria combined, according to the
World Health Organization.

"If we can prevent some of that, I think we should do it," Murray
said, mindful of long-standing protests from animal-rights activists,
ethical concerns and fears of messing with Mother Nature.

The goat's milk represents one of the first genetically engineered
food products designed to improve human health, though none has been
approved for human consumption.

Scientists have been manipulating animal genes for nearly 25 years.
They've changed properties of milk for human food and as raw material for
pharmaceuticals - turning animals into virtual medicine factories. Murray
himself has changed the genes of cows, sheep, pigs and mice.

The goat's-milk experiments, however, are among the few to transfer
human genes to animals, said Michael Fernandez, former director of the Pew
Initiative on Food and Biotechnology.

"It's certainly not the predominant practice right now," Fernandez
said. Private biotechnology companies and universities usually obtain
genetic material from microbes or plants, not humans, he said.

Doug Gurian-Sherman, a biotechnology specialist with the Union of
Concerned Scientists advocacy group, said he has concerns about transgenic
goats.

Should the goats get into the wild - their altered genes indeed make
them more fit to survive - they could more easily multiply and over-browse a
landscape, threatening native species and causing erosion, he said.

"We don't have a regulatory system that addresses these kind of
environmental issues in this country, let alone developing countries,"
Gurian-Sherman said.

Why human genes for goats?

Goats, humans and all other mammals have lysozyme in milk, saliva and
tears. Human breast milk, however, carries at least 1,600 times more than
goat's milk.

UC-Davis dairy goats born with the human gene that regulates lysozyme
in mammary glands have far more lysozyme in their milk than they would
naturally - 67 percent of human levels compared with 0.06 percent, Murray
said.

While other animals carry high levels of the protein, Davis
researchers chose to inject the human gene to minimize chances of an
allergic reaction, should people ever drink the modified goat's milk.

"You drink lysozyme every day in your saliva, so the chances of you
reacting to it are pretty small," said Maga, a research biologist in the
animal-science department.

Several more studies are needed to satisfy food-safety regulators in
the United States and elsewhere that this medicinal milk would be safe to
drink, researchers said.

The latest findings, published in the May issue of the Journal of
Nutrition, show altered goat's milk helps fend off common E. coli-related
illnesses in pigs, which have human-like digestive systems.


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