Auxotrophic Cells for Virus Production and Compositions and Methods of Making

A composition comprising:

• a) a first exogenous nucleic acid construct comprising:
• i) a first polynucleotide of interest;
• and
• ii) a sequence encoding an N-terminal fragment of a functional selectable protein fused in-frame to a sequence encoding an N-terminal fragment of an intein;
• and
• b) a second exogenous nucleic acid construct comprising:
• i) a second polynucleotide of interest;
• and
• ii) a sequence encoding a C-terminal fragment of the intein fused in-frame to a sequence encoding a C-terminal fragment of the functional selectable protein;
• wherein, when expressed, the N-terminal fragment of the functional selectable protein and the C-terminal fragment of the selectable protein are joined together to form the functional selectable protein by the N-terminal fragment of the intein and the C-terminal fragment of the intein,
• wherein the functional selectable protein is selected from the group consisting of glutamine synthetase (GS), phenylalanine hydroxylase (PAH), dihydrofolate reductase (DHFR), and thymidylate synthase (TYMS), and
• wherein the first and second nucleic acid constructs are exogenous to an eukaryotic host cell in which they are introduced.