System for antibody expression and assembly
The present invention provides methods and compositions for expression and production of recombinant antibodies in a host cell system, such as prokaryotic and eukaryotic expression systems. Particularly contemplated are recombinant systems for temporally separated expression of light chain and heavy chain of antibodies. The antibody products including antibody fragments can be used in various aspects of biological research, diagnosis and medical treatment.
1. A process for producing a functional antibody or fragment thereof in a host cell transformed with two separate translational units respectively encoding the light and heavy chains of said antibody or fragment thereof, comprising the steps of: a) culturing the host cell and expressing the light chain for a period of time before the heavy chain is expressed, thereby temporally separating the production of the light and heavy chains; and b) allowing the assembly of the light and heavy chains to form the functional antibody or fragment thereof, wherein the antibody fragment is selected from the group consisting of Fab, Fab′, F(ab′) 2 , F(ab′) 2 -leucine zipper, Fv and dsFv.
2. The process of claim 1 wherein the host cell is prokaryotic, each translational unit further comprising a nucleotide sequence encoding for a prokaryotic secretion signal operably linked to the N′-terminal of the light or heavy chain.
3. The process of claim 2 , wherein the two separate translational units are controlled by different promoters.
4. The process of claim 3 , wherein the two translational units are located on a single recombinant vector.
5. The process of claim 2 , wherein the secretion signal is selected from the group consisting of STII, OmpA, PhoE, LamB, MBP and PhoA.
6. The process of claim 5 , wherein the secretion signal is STII.
7. The process of claim 3 , wherein the promoter for the translational unit encoding the light chain is selected from the group consisting of phoA and trp, and wherein the promoter for the translational unit encoding the heavy chain is selected from the group consisting of trc, TacI, TacII, lpp, lac-lpp, lac, ara, and T7.
8. The process of claim 7 , wherein the promoter for the translational unit encoding the light chain is the phoA promoter and the promoter for the translational unit encoding the heavy chain is the TacII promoter.
9. The process of claim 1 , wherein the antibody is specific to an antigen selected from the group consisting of VEGF, IgE, CD11, CD18 and tissue factor (TF).
10. The process of claim 9 , wherein the antibody is an anti-CD18 antibody or an anti-TF antibody.
11. The process of claim 1 , wherein the antibody is a chimeric antibody.
12. The process of claim 1 , wherein the antibody is a humanized antibody.
13. The process of claim 1 , wherein the antibody is a human antibody.
14. The process of claim 1 , wherein the host cell is a prokaryotic cell from an E. coli strain.
15. The process of claim 14 , wherein the E. coli strain is genetically engineered to over-express at least one chaperone protein selected from the group consisting of DsbA, DsbC, DsbG and FkpA.
16. The process of claim 14 , wherein the E. coli strain is deficient for endogenous protease activities.
17. The process of claim 14 , wherein the genotype of the E. coli strain contains Δprc prc-suppressor.
18. The process of claim 1 , wherein the heavy chain of the antibody is full length.