title: Epi-CHO, an episomal expression system for recombinant protein production in CHO cells.
abstract: This study describes the development of a transient expression system for CHO cells based on autonomous replication and retention of transfected plasmid DNA. A transient expression system that allows extrachromosomal amplification of plasmids permits more plasmid copies to persist in the transfected cell throughout the production phase leading to a significant increase in transgene expression. The expression system, named Epi-CHO comprises (1) a CHO-K1 cell line stably transfected with the Polyomavirus (Py) large T (LT) antigen gene (PyLT) and (2) a DNA expression vector, pPyEBV encoding the Py origin (PyOri) for autonomous plasmid amplification and encoding Epstein-Barr Virus (EBV) nuclear antigen-1 (EBNA-1) and OriP for plasmid retention. The CHO-K1 cell line expressing PyLT, named CHO-T was adapted to suspension growth in serum-free media to facilitate large-scale transient transfection and recombinant gene expression. Enhanced green fluorescent protein (EGFP) and human growth hormone (hGH) were used as reporter proteins to demonstrate transgene expression and productivity. Transfection of suspension-growing CHO-T cells with the vector pPyEBV encoding hGH resulted in a final concentration of 75 mg L(-1) of hGH in culture supernatants 11 days following transfection.
authors.affiliation: School of Biotechnology & Biomolecular Sciences, University of New South Wales, Sydney NSW, Australia.
authors.forename: Rajkumar
authors.initials: R
authors.lastname: Kunaparaju
authors.forename: Mimi
authors.initials: M
authors.lastname: Liao
authors.forename: Noelle-Anne
authors.initials: NA
authors.lastname: Sunstrom
mesh_terms: D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D016895:Culture Media, Serum-Free; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics; D005786:Gene Expression Regulation; D005822:Genetic Vectors / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D019382:Human Growth Hormone / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics*; D015202:Protein Engineering / Q000379:methods; D011994:Recombinant Proteins / Q000235:genetics* / Q000378:metabolism; D018741:Replication Origin / Q000235:genetics; D014162:Transfection
chemical_list: D000952:Antigens, Polyomavirus Transforming; D016895:Culture Media, Serum-Free; D019309:Epstein-Barr Virus Nuclear Antigens; D011994:Recombinant Proteins; D019382:Human Growth Hormone; D049452:Green Fluorescent Proteins; C417029:EBV-encoded nuclear antigen 1