Allergen-free milk from genetic engineering cow

Genetic Engineering: Cow gives allergen-free milk

02/10/2012

Genetically engineered cow bred with allergen-free milk. Milk. According to a New Zealand research team led by Anower Jabed from the Institute of Biology at the University of Waikato in Hamilton, New Zealand, a common trigger for allergic reactions after milk consumption is the protein beta-lactoglobulin (BLG) found in cow's milk, which is not found in human breast milk , About two percent of infants are allergic to this protein.

For the production of milk without beta-lactoglobulin elaborate procedures are required, not least because the protein is relatively resistant to heat. The New Zealand researchers therefore set themselves the goal of genetically modifying cows so that they directly give beta-lactoglobulin-free milk. As Anower Jabed and Stefan Wagner of the "AgResearch" research center in Hamilton report in the journal "Proceedings of the National Academy of Sciences" (PNAS), they have now succeeded. They introduce genetic information that contributes to the production of certain microRNA into the genes of cattle. These entrapped microRNAs blocked the gene, which is responsible for the production of beta-lactoglobulin, the researchers write. The cultured cow yielded allergen-free milk as a result.

Beta-lactoglobulin in cow's milk reduced by up to 98 percent
For a long time, researchers at the University of Waikato have been looking for ways to breed cows that directly deliver beta-lactoglobulin-free milk. First, they identified ten microRNAs that reduced BLG by up to 98 percent in in vitro screening. The microRNAs block certain genes needed to produce the protein, New Zealand scientists report. In a next step, the identified, particularly effective microRNAs were tested in experiments with mice. The researchers implemented the genetic blueprint for the microRNAs into the genome of mouse embryos, with mice producing the microRNA genes in about 25 percent of the experiments and inheriting them from their offspring. The previously established efficacy has also been confirmed in experiments with mice, write Jabed and colleagues.

RNA blockade by so-called microRNA
In a next step, the most effective microRNA variant was incorporated into the fertilized eggs of cows. The oocytes, who succeeded in doing so, cloned the researchers and used five of the resulting embryos cows, which served as surrogate mothers. A pregnancy was successfully completed and a female calf was born. At the age of seven months, the calf was stimulated by the administration of hormones for milk production. The milk was free from beta-lactoglobulin, Jabed and colleagues report. This proves that the microRNAs successfully and specifically block the production of the allergenic protein. The researchers conclude that "this type of RNA blockade is proving to be an effective strategy for altering the composition of milk, but also other properties of farm animals."

Genetic engineering cows with special features
However, the genetically engineered cow also showed other peculiarities. On the one hand, their milk contained "significantly more of all other milk proteins, especially caseins," say the New Zealand researchers. While Jabed and colleagues describe the high casein content of milk as an advantage, since the milk therefore also contains more calcium and is particularly suitable for cheese production, for example, it should be pointed out that high casein contents pose an allergy risk. Casein is considered one of the common triggers of cow milk allergies. Possibly, therefore, for allergy sufferers in the end by the breeding of genetically modified cows won little.

Doubtful success of genetic engineering
In addition, there are the ethical reservations that fundamentally resonate with such genetic interventions and have a special significance in hereditary manipulations of genetic material. In addition, the cow had no tail, which, however, the researchers probably was not related to the introduced genes. This natural mutation is occasionally observed in cattle. Jabed and colleagues assume that the cell selected for cloning already happened to carry this mutation. However, they could not completely rule out a possible connection with their manipulations of the genetic material. In the case of a critical attitude towards genetic interventions, the actual question arises as to whether the result of a lactobacillin free from the outset justifies the intervention. Especially since other options exist to free the cow's milk from the allergenic proteins in retrospect. (Fp)

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