Immunoglobulin display vectors

1. An expression vector comprising, in a 5′ to 3′ direction:

a promoter;

a first exon encoding an immunoglobulin heavy chain variable domain;

a second exon encoding an immunoglobulin CH1 domain;

a third exon encoding an immunoglobulin hinge domain;

a fourth exon encoding an immunoglobulin CH2 domain;

a fifth exon encoding a first immunoglobulin heavy chain CH3 domain and a cell surface tether domain;

a sixth exon encoding a second immunoglobulin heavy chain CH3 domain,

wherein the polynucleotide sequence encoding said second immunoglobulin CH3 domain is identical to the polynucleotide sequence encoding said first immunoglobulin heavy chain CH3 domain;

a CH2 splice donor site located adjacent to the 3′ end of said fourth exon encoding the immunoglobulin CH2;

a CH3-TM splice acceptor site located adjacent to the 5′ end of said fifth exon encoding the immunoglobulin heavy chain CH3 domain and a cell surface tether domain;

a CH3 splice acceptor site located adjacent to the 5′ end of said sixth exon encoding the second immunoglobulin heavy chain CH3 domain;

wherein said CH2 splice donor site splices alternatively to:

said CH3-TM splice acceptor site to form a first spliced transcript, for producing a membrane-bound immunoglobulin; or

said CH3 splice acceptor site to form a second spliced transcript, for producing a secreted immunoglobulin.

2. The expression vector of claim 1 , further comprising an IRES element and a polynucleotide encoding a heterologous marker protein.

3. The expression vector of claim 2 , wherein said IRES element and said polynucleotide encoding a heterologous marker protein are located downstream of said sixth exon.

4. The expression vector of claim 2 , wherein said polynucleotide encoding a heterologous marker protein and said IRES element are located upstream of said first exon and downstream of said promoter.

5. The expression vector of claim 1 , wherein said cell surface tether domain is selected from the group consisting of: platelet derived growth factor receptor (PDGF-R) transmembrane domain, B7-1 transmembrane domain, asialoglycoprotein receptor (ASGPR) transmembrane domain and glycosidylphosphatidylinositol (GPI) signal domain.

6. The expression vector of claim 1 , further comprising a second promoter operatively linked to a polynucleotide sequence encoding an immunoglobulin light chain variable domain and a polynucleotide sequence encoding an immunoglobulin light chain constant domain.

7. The expression vector of claim 6 , wherein said CH3-TM splice acceptor site comprises the sequence SBSBGBSSSBACAG (SEQ ID NO: 1), wherein B is either G, T, or C, and S is either G or C.

8. The expression vector of claim 6 , further comprising a first recombinase site located upstream of the polynucleotide sequences which encode the immunoglobulin heavy chain constant and variable domains and a second recombinase site located downstream of the immunoglobulin light chain constant and variable domains.

9. The expression vector of claim 1 , wherein said promoter is the cytomegalovirus (CMV) promoter.

10. The expression vector according to claim 1 , further comprising a replication origin which is an EBV OriP sequence.

11. The expression vector of claim 1 , further comprising a polynucleotide sequence encoding an EBNA-1 protein.

12. The expression vector of claim 1 , further comprising a drug resistance gene used for the selection of transfected eukaryotic cells.

13. The expression vector of claim 1 , further comprising a drug resistance gene selected from the group consisting of a puromycin resistance gene, a neomycin resistance gene, a hygromycin gene, a xanthine-guanine phosphoribosyltransferase gene (gpt), a zeocin resistance gene, and a blasticidin resistance gene.

14. The expression vector of claim 1 , further comprising a prokaryotic origin of replication.

15. An isolated eukaryotic host cell comprising a heterologous DNA sequence comprising, in a 5′ to 3′ direction:

a promoter;

a first exon encoding an immunoglobulin heavy chain variable domain;

a second exon encoding an immunoglobulin CH1 domain;

a third exon encoding an immunoglobulin hinge domain;

a fourth exon encoding an immunoglobulin CH2 domain;

a fifth exon encoding a first immunoglobulin heavy chain CH3 domain and a cell surface tether domain;

a sixth exon encoding a second immunoglobulin heavy chain CH3 domain, wherein the polynucleotide sequence encoding said second immunoglobulin CH3 domain is identical to the polynucleotide sequence encoding said first immunoglobulin heavy chain CH3 domain;

a CH2 splice donor site located adjacent to the 3′ end of said fourth exon encoding the immunoglobulin CH2;

a CH3-TM splice acceptor site located adjacent to the 5′ end of said fifth exon encoding the immunoglobulin heavy chain CH3 domain and a cell surface tether domain;

a CH3 splice acceptor site located adjacent to the 5′ end of said sixth exon encoding the second immunoglobulin heavy chain CH3 domain;

wherein said CH2 splice donor site splices alternatively to: said CH3-TM splice acceptor site to form a first spliced transcript, for producing a membrane-bound immunoglobulin; or said CH3 splice acceptor site to form a second spliced transcript, for producing a secreted immunoglobulin.

16. The host cell of claim 15 , wherein said heterologous DNA sequence is stably integrated in said host cell genomic DNA in one or more positions and, wherein said CH2 splice donor site splices to said CH3-TM splice acceptor site at a lower ratio than splicing of the CH2 splice donor site to said CH3 splice acceptor site.