Genetic engineering has been used to make pigs that are immune to a virus that is very common in farms.

I have a suspicion that factory farms are responsible for the prevalence of this virus.

I don't see any biological harm or danger in this genetic modification. It appears to have no effect, other than the pigs do not get sick and have healthier immune systems. That is all to the good.

However, the modification is likely to spread patent pollution that would harm farmers' rights in countries that permit patents on genes to apply to farming of animals.