NASH: Diagnosis and Treatment
Bibliographic record
Abstract
Aim Inhibitors of NS5A are proving to have potent antiviral effects in clinical trials involving patients with chronic hepatitis C, but their mechanism of action remains obscure. To study the mechanism of action of NS5A inhibitors, we compared the kinetics of antiviral suppression with other classes of direct-acting antiviral (DAA) using the genotype 1a cell culture-infectious virus H77S.3. Methods Detailed kinetic analyses of antiviral suppression were performed following treatment with representative protease inhibitors, polymerase inhibitors or NS5A inhibitors. Viral RNA replication was measured by monitoring Gaussia luciferase (GLuc) activity in culture medium from Huh7 cells infected with H77S.3 expressing GLuc and also by quantitative RT-PCR. Infectious virus production from Huh7 cells infected with H77S.3 (both intracellular and extracellular infectivity) was measured by focus forming unit assay. Results Kinetics of antiviral suppression by NS5A inhibitors, measured by GLuc or qRT-PCR, were strikingly different to other classes of antiviral. Despite their high potency, NS5A inhibitors were slow to inhibit viral RNA replication compared to protease or polymerase inhibitors. At 1d after addition of inhibitor, little reduction of RNA replication was observed in GLuc assays (typically less than 50%), even at micromolar concentrations. In contrast inhibition of virus production by NS5A inhibitors was potent and rapid. Following treatment of HCV-infected cell cultures with NS5A inhibitors, maximum inhibition of virus production was observed as early as 12 hours whereas maximum inhibition of RNA replication was not achieved until 3 days. Accumulation of intracellular infectious virus was also rapidly inhibited by NS5A inhibitor treatment, indicating that the early effect on virus production occurs at a stage in the virus life cycle prior to egress but after viral RNA replication -most likely on assembly. Conclusions Our analyses of the kinetics of antiviral suppression of the gt 1a strain H77S.3 by NS5A inhibitors provide direct evidence for a two-pronged mechanism of action. First, NS5A inhibitors cause an extremely rapid drop in virus production by inhibiting virus assembly and release of infectious virus. This rapid effect is followed by a slower reduction in RNA replication.
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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".