Production of proteins in eggs
Methods for preparing recombinant proteins, such as antibodies, in eggs are described. The method offers advantages over existing systems for preparing recombinant proteins including high yield, low cost and compatibility with animal protection regulations. In addition, since eggs are edible food sources the recombinant protein does not have to be isolated from the egg.
1. An egg-laying chicken whose somatic cells contain an expression system comprising (i) a first DNA sequence encoding a human gamma isotype immunglobulin constant region having a CH2-CH3 region in an Fc domain of the constant region; (ii) a second DNA sequence encoding a human immunoglobulin variable region; (iii) a third DNA sequence comprising an immunoglobulin-gene derived promoter sufficient for expression of the human immunoglobulin constant region in the chicken; wherein the egg-laying chicken produces eggs whose yolk contains human gamma isotype immunoglobulin having a constant region encoded by the first DNA sequence and a variable region encoded by the second DNA sequence.
2. A method of producing a human immunoglobulin protein in an egg of an egg-laying-chicken comprising:
constructing a vector comprising an expression system comprising: (i) a first DNA sequence encoding a human gamma isotype immunoglobulin constant region having a CH2-CH3 region in an Fc domain of the constant region (ii) a second DNA sequence encoding a human immunoglobulin variable region, and (iii) a third DNA sequence comprising an immunoglobulin-gene derived promoter sufficient for expression of the human immunoglobulin constant region in the chicken, and
incorporating the vector into a pluripotent chicken cell line,
injecting the cell line into a chicken embryo, hatching an egg-laying chicken that produces an egg whose yolk contains human gamma isotype immunoglobulin having a constant region encoded by the first DNA sequence and a variable region encoded by the second DNA sequence.
3. A method according to claim 2 wherein the vector is further comprised of a negative selection marker.
4. A method according to claim 3 further comprising the step of isolating the human immunoglobulin from the egg.
5. A method according to claim 4 further comprising the step of conjugating the immunoglobulin to a toxin.
6. A method according to claim 4 further comprising the step of formulating the human immunoglobulin in a pharmaceutical formulation.
7. The chicken of claim 1 wherein the egg contains at least 3.46 ng of human gamma isotype immunoglobulin per ml of egg yolk.
8. The chicken of claim 1 wherein the expression system is further comprised of an enhancer.
9. The chicken of claim 1 wherein the second DNA sequence encodes a human immunoglobulin variable region that is specific for an antigen.
10. The chicken of claim 9 wherein the antigen is a pathogen.