Gene-Edited Calf Shows Virus Resistance 

A gene-edited calf shows resistance to a common bovine virus. Bovine viral diarrhea virus (BVDV) causes gastrointestinal and respiratory symptoms as well as reproductive failure in cattle around the world.

Vaccines against the virus exist but the virus evolves quickly and vaccines are not always fully protective. Aspen Workman and colleagues used the CRISPR/Cas9 system to swap out just six amino acids in the bovine CD46 receptor in one calf.

The calf showed a dramatic reduction in susceptibility to the virus and displayed no obvious adverse effects. The CD46-edited calf and a control calf lived together with a calf persistently infected with BVDV.

After two days together, nasal swabs showed similar viral RNA loads in both the control calf and the CD46-edited calf, and both calves developed a fever—but only the control calf developed cough, rhinitis, and redness and chafing around the nostrils.

Bloodwork confirmed that while both calves developed antibodies to the virus, the CD46-edited calf did not have measurable infectious virus in its blood.

According to the authors, the healthy calf provides proof-of-concept for using intentional genome alterations in CD46 to reduce the burden of BVDV-associated diseases in cattle.