If New Zealand researchers have their way, milk allergy suffers may someday be able to douse their cereal with the white stuff, without the digestive discomfort.
Scientists working with the AgResearch company have genetically modified a cow to produce milk without beta-lactoglobulin, or BLG, a milk-whey protein believed to be partially responsible for allergic reactions. Using a process that interferes with the cow’s RNA (which messengers instructions from DNA to the proteins), the researchers reduced BLG gene activity and, therefore, the BLG content in the cow’s milk.
The researchers first tested their RNA procedure in mice — which resulted in a 96% reduction in BLG — before moving on to “Daisy,” a genetically engineered calf that they hormonally induced to lactate. Daisy’s milk had no detectable BLG proteins, but in an unexpected result, it had double the amount of casein proteins. That presents a problem, since casein is also a common trigger of milk allergies.
As Dr. Scott Sicherer, a professor and researcher at the Jaffe Food Allergy Institute at Mount Sinai Hospital in New York, told ABC News, many people with milk allergies react to multiple proteins and casein allergies are especially common. “Casein, actually, is the major milk protein that we believe causes most of the severe milk allergies,” Sicherer said. “Creating a milk enriched with casein proteins would seem problematic given what we know about milk allergy.”
Sicherer said that 13% to 76% of milk allergy sufferers react to BLG, compared with the 92% to 100% of patients who react to caseins. Still, according to the authors, BLG is a significant cause of cow’s milk allergies, which affect up to 3% of infants.
Some observers are calling the new study a “breakthrough.” Scientists have long speculated that canceling out BLG proteins could lead to low-allergy milk. “We developed this scientific model to investigate the effect of knocking BLG protein out on the composition and functional properties of milk, and to determine whether the absence of BLG produces cow’s milk that is hypoallergenic,” said lead study author Stefan Wagner in a statement. “This is the real discovery component to this project, and Daisy provides us with the opportunity to answer a lot of those questions.”
But don’t hold your breath for hypoallergenic milk to hit the supermarket shelves. The New Zealand researchers still have a lot of research to do, such as breeding Daisy to see whether milk composition remains the same with normal lactation.
Beyond the current advancements in low-allergy milk research, Wagner said in the statement that the team’s RNA techniques could also lead to other genetically based benefits, like making livestock more disease-resistant.
The study was published in journal Proceedings of the National Academy of Sciences.