Scientists’ gene-splicing tech creates TB-resistant cattle

Chinese scientists have made a significant breakthrough in their efforts to use genetic engineering as a solution to the problem of bovine TB.

Researchers reported in 2015 they had managed to produce animals harder to infect with TB by inserting a mouse gene into the cow genome.

The team at Northwest A&F University, Shaanxi has now published details of a technique used to produce heightened resistance to TB in dairy cows, without producing unwanted side effects.

See also: Bovine TB resistance gene found in cattle

Yong Zhang, lead author of the research, which appeared in the journal Genome Biology on Wednesday (1 February), said a total of 11 Holstein-Friesian calves have become the first livestock animals to benefit from a gene insertion technique called CRISPR/Cas9n.

The researchers inserted a TB-resistant gene NRAMP1 into a cell derived from dairy cows which was then introduced into an egg cell, which was nurtured into an embryo.

This was transplanted into a cow which produced offspring with no “off-target effects” – the term used to describe unintended interference in the genome.

All calves produced with previously used techniques showed off-target effects, which Farmers Weekly has learned can include marked physical issues.

Dr Zhang said the technique had involved a “meticulous and methodological” approach to identify the best-suited region in which to insert the gene.

He added: “When you want to insert a new gene into a mammalian genome, the difficulty can be finding the best place in the genome to insert the gene.

“You have to hunt through the genome, looking for a region that you think will have the least impact on other genes that are in close proximity.”