Christian Gortázar
Professor of Animal Health at the Institute for Research in Game Resources (IREC) and head of the Health and Biotechnology Research Group (SaBio) at the University of Castilla-La Mancha
The work is very interesting, methodologically sound, and innovative, with the only drawback being the very small sample size (n=4).
Animal genomes have already been edited to improve production traits, such as heat resistance or feed conversion into growth. There is also some precedent for gene editing, for example, to create pigs resistant to the porcine reproductive and respiratory syndrome virus (PRRS). This work proposes the same for an important virus, the pestivirus that causes classical swine fever (CSF) in pigs. The trial, despite including very few experimental animals, is very promising. The implications for CSF control could be significant. However, it is a disease that can be controlled through vaccines, biosecurity, and attention to the wild reservoir. It would be very interesting to achieve similar effects in more insidious diseases that do not yet have good approved vaccines, such as African swine fever.
[Regarding potential limitations] In the case of editing for CSF resistance, a relatively small and simple virus (positive RNA; 12.5 kilobases (kb) in length) has required only one or a few mutations. In complex viruses such as ASF [African swine fever] (DNA, 170-190 kb) or in bacteria with a much larger genome, pig genome editing may be considerably more complex.
On the other hand, this type of genetic editing is obviously only possible/acceptable in livestock, not in wildlife—including potential reservoirs of the pathogen—or in humans. And few countries still accept livestock genome editing in products for consumption and trade.