Yes, building mice so they can infect them with CWD.
They are captive engineered lab mice that live their lives under strict bio security to ensure they aren’t exposed to any pathogens prior to study, and experiments are done in BSL-2 or BSL-3 labs. They may or may not be able to breed-depends on the genes that have been manipulated. They certainly are not kept in an environment where they have unrestricted contact with other mice or are just breeding willy-nilly. Regardless, there is absolutely no difference between these mice and how they’ll be handled vs any of the billions of other transgenic mice that have been used for decades in all types of biomedical research, including on far more dangerous diseases than CWD. Bio security procedures are well established at this point.