The researchers in China have been doing extensive research on gene editing and are progressing rapidly in the field. Previously they had reported gene editing of human embryos. And now a team of Chinese scientists have set their eyes on bovine family and have developed the tuberculosis resistant cows through gene editing.
In developed countries such as Asia and Africa, tuberculosis disease has been quite prevalent among the cattle and has been a huge problem for the cattle farmers since long. So the scientists from Northwest A&F University in Shaanxi, China edited the genes by adopting CRISPR/Cas9 system and injected a protein in cows that help in fighting the tuberculosis-causing bacteria.
As a result of this, the cows did develop some resistance to tuberculosis. This is the first-ever research done related to gene editing to have tuberculosis-resistant cattle and thus comes as a major breakthrough.
CRISPR/Cas9 is the best genome editing tool present today. The scientists used a modified version of the Cas9n enzyme for this study. This enzyme cuts a single strand and helps in much detailed editing causing less harmful mutations so as to insert a gene which would provide resistance to infection.
The scientists had cut the tuberculosis resistance-conferring gene NRAMP1 from an array of mouse white blood cells and glued it into more than 1000 cow embryos and then transplanted them into more than 400 cows. This led to 20 genetically modified cows, 11 of which lived longer than 3 months.
Mycobacterium tuberculosis- the scanning electron micrograph of the bacteria causing tuberculosis
When researchers infected the cows with tuberculosis-causing bacteria Mycobacterium Bovis, their gene-edited cows demonstrated more resistance than the non-gene edited ones.
These cows may not be seen for long in the US because of the draft rules created by the United States Food and Drug Administration. The rules say that the gene-edited animals need to be tested for safety and efficacy just like new drugs. Although, the VP of genetic programs at Select Sires ‘Chuck Sattler’ told Newsweek that some cows already possess tuberculosis resistance-conferring gene.
The scientists originally published their research results on tuberculosis-resistant cows in the ‘Genome Biology’ journal.