Non-human animals, methods and compositions for making and using the same, are provided, wherein said non-human animals comprise a mutant L-kynurenine hydrolase (or kynureninase) gene. Said non-human animals may be described, in some embodiments, as having a genetic modification in an endogenous kynureninase gene so that said non-human animals express a kynureninase polypeptide that includes an amino acid substitution that results in the elimination of an epitope in said kynureninase polypeptide that is present in the membrane proximal external region of human immunodeficiency virus- 1 gp41.
