METHODS OF HOST CELL MODIFICATION
Described herein are novel methods of inserting nucleic acid sequences into host cells. Also described herein are genetically stable host cells comprising inserted nucleic acid sequences and methods of using such host cells in the generation of proteins.
1 - 67 . (canceled)
68 . A host cell comprising a donor plasmid and a helper plasmid,
(a) wherein the helper plasmid comprises: (i) under control of a first promoter, an open reading frame encoding lambda red recombinase; and (ii) under control of a second promoter, an open reading frame encoding a restriction endonuclease that has a recognition sequence that is not present in the host cell genome; and
(b) wherein the donor plasmid comprises: (i) from 5′ to 3′: (1) the recognition sequence of the restriction endonuclease; (2) a first homology region of at least 0.5 kilobases (kb), (3) a heterologous insert DNA of at least 8 kb; and (4) a second homology region of at least 0.5 kb; and (ii) a counterselection marker.
69 . The host cell of claim 68 , wherein the heterologous insert DNA is at least 20 kb.
70 . The host cell claim 68 , further comprising an oligosaccharyl transferase.
71 . The host cell of claim 68 , further comprising at least one glycosyltransferase.
72 . The host cell of claim 68 , wherein one or more genes native to the host cell have been deleted or inactivated.
73 . The host cell of claim 68 , wherein said heterologous insert DNA comprises an rfb cluster of a prokaryotic organism.
74 . The host cell of claim 68 , wherein said host cell further comprises a nucleic acid encoding a carrier protein comprising a consensus sequence for N-glycosylation.
75 . A method of producing a glycoconjugate comprising a carrier protein and an antigen, wherein said method comprises culturing the host cell of claim 74 under conditions suitable for the production of proteins.
76 . A glycoconjugate produced by the method of claim 75 .
77 . An isolated host cell, wherein a heterologous gene that encodes an oligosaccharyl transferase has been inserted into the genome of the host cell.
78 . The isolated host cell of claim 77 , wherein said host cell is E. coll.
79 . The isolated host cell of claim 77 , wherein said gene is the C. jejuni pglB gene.
80 . The isolated host cell of claim 77 , wherein the copy number of the heterologous gene in the host cell is selected from the group consisting of 1, 2, 3, 4, and 5.
81 . The isolated host cell of claim 77 , wherein the copy number of the heterologous gene in the host cell is 1.
82 . The isolated host cell of claim 77 , wherein said host cell comprises a carrier protein comprising a consensus sequence Asn-X-Ser(Thr), wherein X can be any amino acid except Pro.
83 . A method of producing an N-glycosylated protein, wherein said method comprises culturing the host cell of claim 77 under conditions suitable for the production of proteins.