Evidence that the RNAseH activity of the duck hepatitis B virus is unable to act on exogenous substrates
Bibliographic record
Abstract
BACKGROUND: The hepadnaviral reverse transcriptase can synthesize DNA on its native RNA template within viral cores but it is usually unable to synthesize DNA employing exogenous nucleic acids as a template. The mechanism of this template commitment is unknown. Here we provide evidence that the RNAseH activity of duck hepatitis B virus reverse transcriptase may also be unable to act on exogenous substrates. RESULTS: RNAseH assays were performed under a wide variety of conditions employing substrate RNAs of Duck Hepatitis B Virus sequence annealed to complementary DNA oligonucleotides and permeabilized intracellular viral core particles. Temperature, pH, cation type, salt concentration, substrate concentration, and the sequences of the cleavage sites were varied, and the effects of ATP and dNTPs on RNAseH activity were examined. duck hepatitis B virus RNAseH activity was not detected under any of these conditions, although E. coli or Avian Myeloblastosis Virus RNAseH activity could be detected under all conditions. Access of the RNA substrate to the enzyme within the viral cores was confirmed. CONCLUSIONS: These results imply that the RNAseH activity of the DHBV reverse transcriptase may not be able to degrade exogenous RNA:DNA heteroduplexes, although it can degrade heteroduplexes of the same sequence generated during reverse transcription of the endogenous RNA template. Therefore, the RNAseH activity appears to be "substrate committed" in a manner similar to the template commitment observed for the DNA polymerase activity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".