Targeted replacement of a gene without endogenous and selectable residual sequences

摘要

Transgenic mice that produce high levels of humanized antibodies are described. Targeted gene replacement exchanges constant regions of the mouse immunoglobulin heavy and light chain genes with human genes, either through conventional gene targeting, or by use of the bacteriophage-derived Cre-loxP recombination system. The transgenic animals undergo antibody affinity maturation, and a class switch from the native immunoglobulin to the humanized form.