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Epi ‐CHO, an episomal expression system for recombinant protein production in CHO cells
Author(s) -
Kunaparaju Rajkumar,
Liao Mimi,
Sunstrom NoelleAnne
Publication year - 2005
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20534
Subject(s) - chinese hamster ovary cell , transfection , microbiology and biotechnology , plasmid , biology , recombinant dna , expression vector , cell culture , reporter gene , green fluorescent protein , transgene , gene expression , gene , genetics
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 Ori P 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. © 2005 Wiley Periodicals, Inc.