Genetically Modified Goats Take on Child Killers
Rejiggering dairy goats to make their milk provide a diarrhea-preventing protein could save children's lives around the world.
Researchers at the University of California at Davis are teaming up with a herd of goats to attack the world’s second leading cause of childhood death.
The target: diarrhea.
The weapon: goat’s milk.
The dozen-plus Davis goats have been altered with a single human gene that gives their milk extraordinary bacterial fighting abilities. Since the early 1990s, UC Davis animal scientist James Murray has been pushing mice, cows and goats to do a better job of producing the protein lysozyme. His early work focused on how the protein could make processing milk into products like cheese and yogurt easier.
But lysozyme has some powerful antimicrobial properties as well. Murray knew this going in—it was discovered almost a century ago by Alexander Fleming, the man who brought the world penicillin. Shortly after Murray began his experiments, he decided the project should shift focus. “We were always interested in both, but it was clear the bigger issue was helping kids,” says Murray (referring to young humans, not goats).
Lysozyme’s high concentration in breast milk is one of the reasons that nursing babies have fewer tummy troubles than those on formula. But after kids stop breast feeding, lysozyme is not as abundant in their diets. That’s a particular problem in areas where the drinking water is often full of diarrhea-causing bacteria. While lysozyme is present in goat and cow’s milk, it’s at levels too low to make a difference. Goat’s milk, for instance, contains only 0.06 percent of what’s offered by human milk.
So Murray took the human genes responsible for lysozyme production and inserted them into goat’s DNA. The result is goat’s milk with levels of the of the protein at 67 percent of what is present in human milk.
A study Murray and his team published in 2008 in the Journal of Nutrition found that feeding pigs the lysozyme-enhanced milk did their stomachs good. Compared to a control group, the genetically enhanced stuff significantly cut coliform bacteria in the pigs’ small intestines. And a more recent study observed that the milk both tamped down inflammation in the gut while also beefing up the cells that serve as the intestine’s first line of defenses against bacteria.
Murray isn’t the only one trying to use genetically modified goats to save lives. Researchers at Texas A&M University are working to produce goats milk that contains a malaria vaccine.
Sounds promising, right? As it turns out, the biggest hurdles that these projects face are not scientific, they’re regulatory.
In 2009 Murray formed a partnership with some Brazilian researchers to produce a herd of his transgenic goats in their country. The research was more likely to get funded since childhood diarrhea is a more pressing problem in Brazil, and funding for genetic modifications always is difficult because the research makes the public squeamish, says Murray. Still, he and his partners expected to start human trials within two years. But three years later, the semen meant to jump-start the South American herd hasn’t left U.S. soil.
“We have approval to have animals there,” says Murray, “but we have not been given permission for the semen to be shipped.” The Brazilian government requires a certain kind of semen center certification that is not standard practice for the USDA. The discord in regulations has made building a new herd difficult. Attempts at transgenic goats via cloning haven’t gotten off the ground either.
Regulators in the U.S. are similarly moving slowly to open their gates. Genetically engineered salmon have waited more than a decade to get FDA approval for them to be introduced in the wild. Despite public hearings and an advisory committee’s attention, no decision has been made.
Later this year Murray will test the milk in monkeys. The results could mean a lot for his goats – and for sick children around the world.