Researchers from the College of Veterinary Medicine, Northwest A&F University in Shaanxi, China claim they have successfully genetically modified cows to be resistant to bovine tuberculosis.
What Is Bovine Tuberculosis?
Bovine tuberculosis is an infectious disease caused by the Mycobacterium bovis bacteria. It can also spread to and affect other mammals, including deer, goats, pigs, cats, dogs, and humans.
In cattle, bovine tuberculosis has the characteristics of a respiratory disease, causing weight loss, cough, and fever in severe cases. It is mostly asymptomatic, although evidence of infection can be seen in the lymph glands, throat, or lungs of the animal.
Bovine TB can spread from cattle to cattle through exposure to breath or discharges from the infected animal's mouth or nose, consumption of infected milk, before birth through the placenta, and indirectly via environmental contamination.
CRISPR-Cas9 System
Using an advanced technique called clustered regularly interspaced short palindromic repeats (CRISPR, pronounced crisper), or more specifically, the CRISPR-Cas9 system, a genome editing tool, the scientists inserted a gene linked to tuberculosis resistance into 20 cattle.
Results show that 11 of the genetically modified cows lived beyond the age of 3 months and were more resistant to the disease compared to their non-genetically modified counterparts. The researchers didn't note any side effects in the animals as a consequence of genetic modification.
The full study was published online on Jan. 31 in the journal Genome Biology.
Is This The End Of Bovine TB And Antibiotic Use In Livestock?
With this new development and the use of the CRISPR/Cas9 system, the authors are hopeful that their study will be valuable for agricultural applications.
Many developing countries have resorted to slaughtering thousands of infected cattle annually to put an end to bovine TB, but to no avail. More than 26,000 cattle were reportedly slaughtered in the UK back in 2013, costing taxpayers at least £100 million or more than $120 million.
"I think this is a very neat study that demonstrates the feasibility of introducing a desired gene of interest via a potentially safer way," Suk See De Ravin, a researcher with the Laboratory of Host Defenses, under the U.S. National Institutes of Allergy and Infectious Diseases, remarked.
De Ravin, who is not part of the study, also noted that this new information may be the key to raising animals with a robust resistance against diseases and may potentially pave the way to reducing or even eliminating the excessive use of antibiotics in livestock, which has its negative effects on human health, too.
However, some experts think otherwise.
"Although it is a thorough and novel paper on using gene technology in transgenic cattle at this stage I doubt if the research will have any application to prevention of TB in cattle using transgenic technology," Ian McConnell, emeritus professor of veterinary science at the University of Cambridge, told the BBC, adding that TB in cattle is more complicated than we can imagine.
