TB-resistant cattle are a reality

A new technique has produced live animals with 
increased resistance to this dangerous disease

Researchers say they’ve found a high-tech way to produce cattle with genetic resistance to bovine tuberculosis.

Writing in the open-access journal Genome Biology, Chinese researchers from the Northwest A&F University in Shaanxi, China say CRISPR gene-editing technology allowed the breakthrough.

Dr. Yong Zhang, lead author of the research, said: “We used a novel version of the CRISPR system called CRISPR/Cas9n to successfully insert a tuberculosis-resistance gene, called NRAMP1, into the cow genome. We were then able to successfully develop live cows carrying increased resistance to tuberculosis.”

CRISPR technology has become widely used in the laboratory in recent years as it is an accurate and relatively easy way to modify the genetic code. However, sometimes unintentional changes to the genetic code occur. Zhang says the new technique has shown no such effects.

“We employed a meticulous and methodological approach to identify the best-suited region for gene insertion, which we show has no detectable off-target effects on the bovine genome,” Zhang said.

A total of 11 calves with new genes inserted using CRISPR were able to be assessed for resistance to tuberculosis and any off-target genetic effects.

When the calves were exposed to M. bovis, the bacterium that causes bovine tuberculosis, the researchers found that transgenic animals showed an increased resistance to the bacteria measured by standard markers of infection in a blood sample. They also found that white blood cells taken from the calves were much more resistant to exposure in laboratory tests.

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