Chinese researchers from Northwest A&F University has successfully produced live cows with increased resistance to bovine tuberculosis (TB) for the first time. They have managed to use the CRISPR gene-editing technology for the same.
They used a modified version of the CRISPR system called CRISPR/Cas9n to insert a new TB resistance gene-NRAMP1 into the genome of bovine foetal fibroblasts which is a cell derived from female dairy cows. These cells were then used as donor cells in a process called somatic cell nuclear transfer, where the nucleus of a donor cell carrying the new gene is inserted into an egg cell, known as an ovum, from a female cow.
These ovum were then nurtured in the lab into embryos before being transferred into mother cows for a normal pregnancy cycle, in which cows were produced with no off target effects on the animals' genetics.
The results revealed that NRAMP1 had successfully integrated into the genetic code at the targeted region in all of the calves.When exposed to Mycobacterium bovis (M. bovis) - the bacterium that causes bovine TB - the transgenic animals showed an increased resistance to the bacteria measured by standard markers of infection in a blood sample.
Lead author Yong Zhang said, "We used a novel version of the CRISPR system to successfully insert a TB resistance gene into the cow genome. We were then able to successfully develop live cows carrying increased resistance to TB. Importantly, our method produced no off target effects on the cow genetics meaning the CRISPR technology we employed may be better suited to producing transgenic livestock with purposefully manipulated genetics"