First TB-resistant cows created using gene-editing technique
Designer cows have been created that are resistant to tuberculosis (TB) – one of the biggest problems facing dairy farmers around the world.
Badgers are controversially being culled in an effort to stop the bovine form of the disease, which would be unnecessary if cows can be made naturally resistant.
So advances in preventing the disease could be welcomed by farmers whose cattle have to be killed if they catch TB. Researchers used a ‘cut and paste’ gene editing technology, known as CRISPR, to insert a new gene into the cow’s genetic codes.
CRISPR technology precisely changes target parts of genetic code. Unlike other gene-silencing tools, the CRISPR system targets the genome’s source material and permanently turns off genes at the Deoxy ribonucleic Acid (DNA)/genetic material level.
The DNA cut – known as a double strand break – closely mimics the kinds of mutations that occur naturally, for instance after chronic sun exposure. But unlike Ultra Violet (UV) rays that can result in genetic alterations, the CRISPR system causes a mutation at a precise location in the genome. When cellular machinery repairs the DNA break, it removes a small snip of DNA. In this way, researchers can precisely turn off specific genes in the genome
The gene led to no adverse effects on the animal, according to the researchers, but did greatly increase TB resistance. Scientists at the College of Veterinary Medicine, Northwest A&F University in Shaanxi, China, inserted a gene into the genetic code of calves.
Dr. Yong Zhang, lead author of the research, said that insertion of a gene called NNRAMP1 led to disease resistant cattle. To carry out the process, the gene was inserted into the nucleus of another kind of bovine cell, called a fibroblast, taken from a cow foetus.
Some people are voicing their opposition to the gene-editing technology. Earth Open Source, a European NGO funded by the Maharishi cult, recently attacked the claim that CRISPR was more accurate than previous genetic engineering tools.
However, the claim has since been disputed by Genetic Literacy Project, who said that ‘the cult’s description has little to do with the use of the technology in plants.’
David Stern, a plant biologist and president of the Boyce Thompson Institute for Plant Research, recently warned in a statement that people might perceive gene editing as ‘playing God.’ This edited nucleus was then transferred to the egg cell of a cow. The eggs were nurtured in the laboratory, and then fertilised in the lab, to form embryos. These were then inserted into the cow and developed and were born as normal.
A total of 11 calves with new genes inserted using CRISPR were assessed for resistance to tuberculosis and any adverse genetic effects. The authors said that when exposed to bovine TB bacteria the researchers found the transgenic animals showed an increased resistance.
*Adapted from DailyMailUK Online