Researchers at China’s Northwest Agriculture and Forestry University devised a CRISPR/Cas 9 technique to give cloned dairy cows a leg up against the bacteria behind bovine tuberculosis (Mycobacterium bovis). Last year, another group used TALENs, an older gene-editing technology, to create two cows without horns, but this is the first time CRISPR has been reported to insert a gene in cattle.
The team cut and pasted a bovine gene for NRAMP1, a protein linked to resistance against TB and other bacterial infections, into fetal dairy cow genomes. When scientists use CRISPR/Cas 9 to insert genes, there could be unintended effects or mutations in other parts of the genome. In this case, researchers strategically selected an area of DNA to reduce those effects.
Through cloning, mother cows gave birth to 20 calves with the NRAMP1 gene. Of the 11 calves that survived past three months, six were tested for TB resistance and showed heightened TB-fighting abilities in lab tests, the team reports January 31 in Genome Biology.
Editor’s note: This post was updated on February 9, 2017, to correct the spelling of the gene added in the CRISPR process. On February 13, it was amended to clarify that six of the surviving calves were tested for TB resistance.