Abstract: The invention relates to transgenic non-human animals capable of producing heterologous antibodies and transgenic non-human animals having inactivated endogenous immunoglobulin genes. In one aspect of the invention, endogenous immunoglobulin genes are suppressed by antisense polynucleotides and/or by antiserum directed against endogenous immunoglobulins. Heterologous antibodies are encoded by immunoglobulin genes not normally found in the genome of that species of non-human animal. In one aspect of the invention, one or more transgenes containing sequences of unrearranged heterologous human immunoglobulin heavy chains are introduced into a non-human animal thereby forming a transgenic animal capable of functionally rearranging transgenic immunoglobulin sequences and producing a repertoire of antibodies of various isotypes encoded by human immunoglobulin genes. Such heterologous human antibodies are produced in B-cells which are thereafter immortalized, e.g.

Abstract: This invention relates to the production of recombinant proteins in mammals' milk. Particularly, this invention relates to an expression system comprising the mammal's casein promoter which when transgenically incorporated into a mammal permits the female species of that mammal to produce the desired recombinant protein in or along with its milk. This invention also relates to the transgenic mammal that produces the desired recombinant product in its milk.