MuirfField's medical experiments in clued cross-species DNA which is essentially two sets of DNA within a single body. Given time the genetically modified DNA will change the person's physiology which will result in hybrid physiology a human animal physiology. MuirfField used what I call the Beast serum. This serum was created by MuirfFeild scientist, who were then instructed by the u.s. government to inject it into their soldiers (how many is currently unknown), in a bid to create genetically enhanced super-soldiers. The serum was administered through an injection in the side of each subjects neck.
The serum is in itself was based on the DNA from Proto Beast that was obtained by MuirfField.
Cure: The effect of the serum can be undone if a beast temporarily dies and is resuscitated afterwards.
Gene-Splicing:
Gene-splicing is the act of taking adaptations from one or more species and applying them to another. If successful that the result is cross- species genetics, which will if given time will lead to a change in physiology, most notably human-animal physiology.
Catherine Chandler and Vincent Keller