October 1, 2012

expert reaction to new research into hypoallergenic milk from a GM cow

Researchers writing in PNAS* used RNA interference, a process that inhibits the expression of certain genes, to engineer a dairy cow capable of producing high-protein milk with hypoallergenic qualities.

Prof Bruce Whitelaw, Professor of Animal Biotechnology at the University of Edinburgh, said:

 “Milk is a major source of protein for humans across many parts of the world; however, there is a relatively high incidence of allergic reactions to proteins in milk.  The authors convincingly demonstrate that RNA interference (RNAi) technology can be combined with transgenic or GM technology to produce cattle with minimal levels of the major milk allergen beta-lactoglobulin.  This reduction of one milk protein level was accompanied by an increase in others, namely the caseins.  This is notable since it represents one of the few RNA interference success stories in mammals and offers a good example of how these technologies can be used to provide alternative strategies to current manufacturing process.

 “RNAi has a long history of successful application in diverse species from plants to worm – this is the first spectacular report for livestock.  RNAi knocks down gene activity, i.e. it reduces gene activity without eliminating it. In this study beta-lactoglobulin levels are reduced to only 5% of original levels.  There are currently projects that are attempting to knock out beta-lactoglobulin in livestock which should reduce this protein levels to zero.  Theoretically RNAi offers fine tuning in comparison to knock out strategies.

 “Time will tell how widely applicable RNA interference will be in GM livestock – but this is certainly a milestone study in this field.  It is likely, however, that different applications of the emerging DNA editor technologies (e.g. TALENs and ZFNs) will provide even more elegant strategies for genome engineering that combine target site specificity with the ability to fine tune expression levels that do not fall under the ‘transgenic’ banner in the near future.”

* ‘Targeted microRNA expression in dairy cattle directs production of β-lactoglobulin-free, high-casein milk’ by Anower Jabed et al. as published in PNAS.