KSHV Activates Unfolded Protein Response Sensors but Suppresses Downstream Transcriptional Responses to Support Lytic Replication
Bibliographic record
Abstract
Herpesviruses usurp host cell protein synthesis machinery to convert viral mRNAs into proteins, and the endoplasmic reticulum (ER) to ensure the proper folding, post-translational modification and trafficking of secreted and transmembrane viral proteins. Overloading the ER folding capacity activates the unfolded protein response (UPR), whereby sensor proteins, ATF6, PERK and IRE1, initiate a stress-mitigating transcription program that accelerates the catabolism of misfolded proteins, while increasing the ER folding capacity. Kaposi’s sarcoma-associated herpesvirus (KSHV) can be reactivated from latency through the chemical induction of ER stress, which causes an accumulation of the XBP1s transcription factor that transactivates the viral RTA lytic switch gene. The presence of XBP1s-responsive elements in the RTA promoter suggests that KSHV evolved a mechanism to respond to ER stress. Here, we report that ATF6, PERK and IRE1 were activated upon reactivation from latency and were required for efficient KSHV lytic replication. The genetic or pharmacologic inhibitions of each UPR sensor reduced virion production. Despite UPR sensor activation during KSHV lytic replication, downstream UPR transcriptional responses were restricted: (1) ATF6 was cleaved to activate the ATF6(N) transcription factor but ATF6(N)-responsive genes were not transcribed; (2) PERK phosphorylated eIF2, but ATF4 did not accumulate; (3) IRE1 caused XBP1–mRNA splicing, but the XBP1s protein did not accumulate and the XBP1s-responsive genes were not transcribed. The complementation of XBP1s deficiency during KSHV lytic replication inhibited virion production in a dose-dependent manner in epithelial cells. Taken together, these findings indicate that, while XBP1s plays an important role in reactivation from latency, it can inhibit virus replication at a later step, which the virus overcomes by preventing its synthesis. These findings suggest that KSHV hijacks UPR sensors to promote efficient viral replication while sustaining ER stress.
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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 | 0.000 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".