Expression of a Toxoneuron nigriceps polydnavirus-encoded protein causes apoptosis-like programmed cell death in lepidopteran insect cells
Bibliographic record
Abstract
The polydnavirus Toxoneuron nigriceps bracovirus (TnBV) is an obligate symbiont associated with the braconid wasp T. nigriceps, a parasitoid of Heliothis virescens larvae. Previously, to identify polydnavirus genes that allow parasitization by altering the host immune and endocrine systems, expression patterns of TnBV genes from parasitized H. virescens larvae were analysed and cDNAs were obtained. To study the function of the protein from one such cDNA, TnBV1, overexpression of the protein was attempted by using the baculovirus Autographa californica multicapsid nucleopolyhedrovirus. Recovery of stable recombinant virus was unsuccessful, with the exception of recombinants with deletions/mutations within the TnBV1 gene. It was hypothesized that TnBV1 expression was cytotoxic to the Spodoptera frugiperda (Sf21) insect cells that were used to produce the recombinants. Therefore, the Bac-to-Bac system was used to create recombinant baculoviruses maintained in Escherichia coli expressing either TnBV1 (Ac-TnBV1) or an initiator-methionine mutant [Ac-TnBV1(ATG-)]. Microscopy revealed substantial cell death of Sf21 and High Five cells from 48 h post-infection with Ac-TnBV1, but not with the Ac-TnBV1(ATG-) recombinant virus. Ac-TnBV1-infected Sf21 cells, but not those with parental virus infection, showed an increased caspase-3-like protease activity, as well as increased terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling (TUNEL) for breaks in host genomic DNA. Although indicative of apoptosis, blebbing and apoptotic bodies were not observed in infected cells. Transiently expressing TnBV1 alone caused TUNEL staining in High Five cells. These data suggest that TnBV1 expression alone can induce apoptosis-like programmed cell death in two insect cell lines. Injection of Ac-TnBV1 budded virus, compared with parental virus, did not result in an alteration of virulence in H. virescens larvae.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".