QMCF Technology is a stable episomal expression system that uses specific mammalian cells and appropriate vectors for production of secretable and intracellular recombinant proteins, antibodies, virus-like particles; and for expression of intracellular proteins at physiologically relevant level for development of cell-based assays for screening purposes.
The features of transient
and stable expression are successfully combined in QMCF Technology: expression
stays episomal, without integration into the host cell chromosome, however, under selective conditions the expresison lasts up to several weeks and months and
allows generation of cell banks.
QMCF cell lines express two viral proteins: Epstein-Barr Virus (EBV) EBNA-1 protein and mouse polyomavirus (Py) Large T antigen to support stable maintenance and replication of QMCF plasmids. QMCF plasmids carry hybrid replicons comprised of mouse polyomavirus enhancerless core replication origin in combination with Epstein-Barr virus EBNA-1 protein binding sites (FR – Family of Repeats) as nuclear retention element. These proteins ensure stable replication and maintenance of QMCF expression vectors in QMCF cells. Similar system has been engineered where FR has been replaced with Bovine Papillomavirus type 1 E2 protein multimeric binding sites and in cell lines BPV1 E2 protein expression cassette has been added to the genome of QMCF cells.
QMCF cell lines are stable cell lines expressing EBV EBNA-1 protein and PyV Large T antigen. CHO based QMCF cell line has named CHOEBNALT85. Other QMCF cell lines are derived from HEK293, U2OS or Cop5.
pQMCF expression plasmids comprise mouse polyomavirus (PyV) core origin and FR element of EBV, and an expression cassette with multicloning sites (MCS) for expression of gene of interest (GOI)
|Southern blot analysis of pQMCF plasmid expressing human IgG1 in CHOEBNALT85 cells 2-16 days after transfection|
QMCF Technology highlights
- the plasmids stably replicate in QMCF cells and maintain their copy number during cell division in several weeks
- scale-up from a small initial transfection volume (20 ml) to several litres (>20L) of final production volume is feasible
- generation of production cell banks within 10 days after transfection is feasible
- easy manipulation combined with stable expression enable quick, robust and cost-effecitive method for protein production
- Silla, et al, Episomal Maintenance of Plasmids with Hybrid Origins in Mouse Cells; Journal of Virology, Dec 2005: 15277-15288. Read the paper here
- European/EPO Patent No: EP1851319
- USPTO Patent No: 7.790.446
- USPTO Patent No: 8.377.653
- Australian Patent No 2006212393
- Canadian Patent No 2.594.834
- Japanese Patent 2007-554514
- USPTO Patent Application No: 13.748.017