Extended gene expression for Gag VLP production achieved at bioreactor scale
Bibliographic record
Abstract
Abstract BACKGROUND Transient gene expression has been widely used for virus‐like particles (VLP) production in both small‐ and large‐scale systems. The extended gene expression (EGE) technique is based on repeated medium exchanges and retransfections of cell culture to prolong the production phase. The aim of this study was to demonstrate scalability of the approach by operating EGE continuously in a controlled bioreactor to obtain similar results to those achieved with shake flask EGE for VLP production. A standard batch cultivation was also carried out in shake flask. RESULTS For EGE in shake flasks and in a bioreactor, cell viability was comparable; however, the bioreactor enabled much higher cell densities and specific growth rates than the shake flasks. Owing to this increased cell growth in the bioreactor, the percentage of GFP‐positive cells was considerably lower at the end than in the shake flasks. GagGFP VLP titers were similar in both shake flasks and bioreactor. Nanoparticle tracking analysis revealed that the ratio of VLPs/total particles (VLPs and cell vesicles) was higher in the shake flasks than in the bioreactor, possibly due to higher cell densities achieved in the bioreactor. CONCLUSIONS In this study, EGE methodology was carried out in a bioreactor system for the first time while maintaining GagGFP production titers. Overall, our findings call for further optimization and implementation of common downstream processing steps to improve yield and VLP quality. © 2018 Society of Chemical Industry
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 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".