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Allergy-free milk: nothing to sneeze at

23 Jan, 2013

Scientists from AgResearch and the University of Waikato have created a genetically modified cloned cow to produce milk lacking the whey protein beta-lactoglobulin (BLG), a protein to which an estimated 2–6% children are allergic.

Testing BLG inhibition system

The cow, called Daisy, is now just over a year old. She is the final product of years spent testing a BLG inhibition system, first in single cells and then in mice, before finally moving to cows.The system involves a process called RNA interference, which stops target genes from producing proteins.

However, contrary to some media reports, those with milk allergies won’t be gulping back a glass of the white stuff any time soon. Researchers expect it will be years, perhaps even decades, before milk from cows like Daisy would be considered for commercialisation, let alone human trials. New Zealand has restrictive genetic modification policies that mean the research and even Daisy herself are contained well away from the public.

Cautious approach to artificially produced milk

In an interview with the Science Media Centre, Dr Mike Boland (Principal Scientist and Executive Officer at Massey University’s Riddett Institute, which studies food science and nutrition) said that, while the research was an exciting and interesting piece of work, a cautious approach was warranted.

“The fact that these scientists have produced a viable calf that does not produce this protein is… scientifically very interesting. Any commercial potential of this knockout is still some distance away. Although the composition of milk from this experimental animal has been shown to be quite unusual, this composition must be viewed with caution, as it was artificially produced [induced by hormones] rather than from natural lactation [Daisy is too young to produce milk naturally]. It also remains to be seen if this animal is able to breed.

“Beta-lactoglobulin has long been regarded as the major allergen in cows’ milk and so a niche opportunity must exist for milk such as this, for use in hypoallergenic infant formulas and the like. The absence of beta-lactoglobulin also has the potential to improve some processing properties of milk.”

BLG important for muscle metabolism

“This protein, however, is the main source of branched-chain amino acids in whey, and these are important for muscle metabolism – which is why whey powders are favoured by sports people and body builders. It is also the source of gelling functionality in whey products. And, of course, most people are not allergic to cows’ milk. There is therefore not a case for getting rid of beta-lactoglobulin from all milk.”

Also, it should be noted that, while BLG is the main known allergen, there are also some other proteins in milk to which people can be allergic.

It is not known whether Daisy can breed yet, and interestingly, she was born with no tail. Scientists at AgResearch are unsure if this is a result of the cloning process or just a coincidence – sometimes cows are born with no tails. If Daisy is able to produce offspring, their tails, or lack of them, will shed more light on the matter.

The research was published in the 16 October 2012 edition of the Proceedings of the National Academy of Sciences (PNAS).


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