About making a CHO production cell line “research-friendly” by genetic engineering
Bibliographic record
Abstract
The use of Chinese Hamster Ovary (CHO) cells for transient gene expression is gaining importance steadily, as it has been shown that both quality and quantity of proteins derived from CHO cells differs from and can even be superior to material derived from Human Embryonic Kidney (HEK293) cells [1][2][3][4].In order to augment yields HEK cell lines have been genetically modified, by e.g.stable integration of an expression cassette coding for the Epstein-Barr Virus Nuclear Antigen 1 (EBNA1) in conjunction with expression plasmid vectors containing the EBNA1 interaction site oriP.Here we describe the generation of a CHO cell line stably expressing the EBNA1 gene to enhance yields after large scale transient transfection with polyethylenimine (PEI).An expression plasmid featuring the EBNA1 gene was transfected into an in-house available CHO wild type cell line by nucleofection and several stable pools were established by antibiotic selection.In a first approach, 133 clones were then isolated by limiting dilution cloning and subsequently expanded for further analysis.The approach aimed at identifying clones showing both the presence of EBNA1 protein and enhanced yields after PEI-mediated transient expression of a reporter protein at the same time.Cell lysates or nuclear and cytoplasmic protein extracts from these clones were tested for presence of EBNA1 protein by Western Blot.An in-licensed cell line, CHO EBNALT85 (Icosagen AS, Tartu, Estonia) expressing the full length EBNA1 gene, and the HEK293-6E cell line (from the group of Y. Durocher, NRC, Canada) expressing a truncated EBNA1 gene served as positive controls.A number of commercially available anti-EBNA1 antibodies were tested in Western blotting, but most antibodies failed to detect the EBNA1 protein produced by these positive control cells.Only
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".