Genome editing made it possible to obtain calves resistant to bovine diarrhea virus (BVDV). This has been reported by the US Department of Agriculture.
This disease develops reproductive failure as well as gastrointestinal and respiratory symptoms in cows worldwide. There are vaccines against this virus, but it mutates quickly and therefore it is not always possible to prevent the disease. Aspen Workman and colleagues used the CRISPR/Cas9 genome editing system to replace six amino acids in the bovine CD46 receptor in a calf.
As a result, the calf sharply decreased susceptibility to the virus and no side effects were detected. During the trial, one CD46-modified calf and one control lived with a BVDV-infected calf. Two days later, nasal swabs showed the same amount of viral RNA in both a normal calf and a genome-edited calf. Both calves developed fever, but only control calves developed cough, rhinitis, redness and irritation around the nostrils.
Blood testing confirmed that although both calves developed antibodies to the virus, the CD46-regulated calf did not have a significant viral load after symptom resolution. The authors hope their discovery will allow the breeding of disease-resistant animals.
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