Cattle with increased TB-resistance have been developed at a Chinese university.
Cattle with increased TB resistance have been successfully produced for the first time using gene-editing technology.
The responsible researchers, from the College of Veterinary Medicine, Northwest A&F University in Shaanxi, China, used a modified version of the clustered regularly interspaced short palindromic repeats (CRISPR) gene-editing technology to insert a new gene into the cow genome.
Dr Yong Zhang, lead author of the research, says: “We successfully inserted a tuberculosis resistance gene into the cow genome. We were then able to develop live cows carrying increased resistance to TB. Importantly, our method produced no off-target effects on the cow genetics."
Gene-editing technology has become widely used in labs in recent years as it is an accurate and relatively easy way to modify the genetic code. However, unintentional changes to the genetic code can occur, so finding ways to reduce these instances is a priority for genomic research.
A total of 11 calves with new genes inserted were able to be assessed for resistance to TB and any off-target genetic effects. Genetic analysis of the calves revealed the TB-resistance gene had successfully integrated into the genetic code at the targeted region in all of the calves. The CRISPR/Cas9n technology used did not produce any off-target effects, unlike in all calves used in previous experiments.
When the calves were exposed to M. bovis, the bacterium causing TB, the researchers found transgenic animals showed an increased resistance to the bacteria measured by standard markers of infection in a blood sample. They also found white blood cells taken from the calves were much more resistant to M. bovis exposure in laboratory tests.
Dr Zhang says: “Our study is the first demonstrating the CRISP/Cas9n system can be used to create transgenic livestock with no detectable off-target effects. Our work has led to the discovery of a useful position in the bovine genome which can be targeted with this gene editing technology to successfully insert new genes to benefit agricultural livestock.”