Scientists create cow that produces hypoallergenic milk
Allergic to milk? A genetically engineered cow from New Zealand may be here to help.
Through genetic modifications, scientists at the government-owned research facility AgResearch have bred a cow that does not produce a protein known to cause milk allergies in many children.
"We were successful in greatly reducing the amount of beta-lactoglobulin (BLG), a milk whey protein which is not in human breast milk and which can cause allergic reactions," study author Dr Stefan Wagner, a scientist at AgResearch said in a press release. "Two to three percent of infants are allergic to cow's milk, and BLG allergies make up a large part of that percentage."
Their research is published in the Oct. 1 issue of Proceedings of the National Academy of Sciences.
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Scientists first tested if they could produce milk without beta-lactoglobulin in mouse experiments, by engineering mice to produce BLG protein from sheep's milk. They then used a technique in which they took two strands of microRNA and introduced then into the mouse to "knock down" the genes that produced sheep BLG protein. That differs from the process in genetic "knock out" animal experiments in that there are still small amounts of protein produced.
Their mouse experiment resulted in a 96 percent reduction in sheep BLG protein in mouse milk.
The scientists then wanted to try their experiment in cows. They bred a cow named Daisy to express the same two micro RNA strands that knocked out the sheep's milk protein, but this time targeted it to take out the genes that produce BLG protein for cow's milk. After using hormones to induce lactation - since Daisy was still two years from natural lactation - the calf produced milk that had no detectable levels of BLG protein. The milk also contained double the amount of casein proteins, another type of protein in which high levels is used to enhance cheese yields from milk.
Daisy was also born without a tail for unknown reasons.
"We now want to breed from Daisy and determine the milk composition and yield from a natural lactation," Wagner said. "We also want to investigate the origin of Daisy's taillessness, a rare congenital disease in cows."
Wagner also hopes the research could lead to other genetically modified livestocks, such as animals with better disease resistance.
While the milk may help many infants and children, it only addresses allergies due to BLG protein, which many children grow out of by the time they turn 3 years old. The milk also won't help anyone with lactose intolerance, since that is caused by lacking an enzyme that breaks down the sugar in milk.
What's more, it's too early to even know if the milk is safe for human consumption.
AgResearch also says the process of producing the cows is expensive, so while it is "feasible" to engineer dairy cattle lacking BLG, initial research will only be limited to a few animals.
Several scientists expressed caution over the application of the new findings.
"It's only one of several proteins in milk that can cause allergies and one of the other ones that can do that is actually increased rather than reduced," Dr. Robert Loblay, head of the allergy unit at the Royal Prince Alfred Hospital in Sydney told the Australian ABC News.
"There would be a long way to go from having a cow on the ground to producing this desirable milk, and getting it approved, and having it accepted by the population as a substitute for regular cow's milk," Dr. R. Michael Roberts, professor of animal science and biochemistry at the University of Missouri-Columbia, who edited the research, told Health.com.
AgResearch has more information on Daisy and her hypoallergenic milk.
