The present invention provides non-human animal, its preparation and application and compositions, wherein the non-human animal includes saltant type L- kynurenine hydrolases (or kynureninase) gene. In some embodiments, the non-human animal can be described as having the genetic modification in endogenous kynurenin enzyme gene, so that non-human animals expression includes the kynurenin enzyme polypeptide of amino acid replacement, the amino acid replacement causes the epitope in the kynurenin enzyme polypeptide being present in the nearly film end outside area of human immunodeficiency virus-1 gp41 to be eliminated.
