Nipah virus matrix protein utilizes cortical actin to stabilize the virus assembly sites and promote budding
Bibliographic record
Abstract
Abstract Several families of enveloped viruses assemble and bud from the host cell plasma membranes (PM), including paramyxoviruses. Nipah virus (NiV) is a deadly zoonotic paramyxovirus causing yearly outbreaks in Southeast Asia with >75% mortality. NiV encodes matrix proteins (M) that drive assembly and budding. NiV-M forms dimers and interacts with membrane lipids in the host cell’s PM for budding. Using single-molecule localization microscopy and single-particle tracking, we show that the host F-actin maintains the nanoscale organization of NiV assembly sites at the PM. This F-actin-dependent integrity of NiV assembly sites is observed at the membrane retention stage after the assembly process is complete, rather than during the recruitment of NiV-M molecules to these sites. NiV-M interacts with actin via its C-terminal domain. We also show that the actin-branching factor, Arp2/3 complex, promotes virus-like-particle production. Meanwhile, inhibiting Arp2/3 disfavors the PM retention of NiV assembly sites and NiV-M-mediated generation of membrane protrusions, but does not affect the assembly rate. This suggests that Arp2/3-nucleated actin polymerization and branching are critical for maintaining NiV-M assembly sites at the PM, allowing it to facilitate membrane protrusion generation for virus budding. Our findings support the following model: NiV-M interacts with F-actin through its C-terminus to remain at the host PM after assembly completion. This F-actin-dependent retention is promoted by the Arp2/3-driven actin branching and polymerization, which also drives the formation of NiV-M-induced membrane protrusions necessary for virus budding. Significance Nipah virus (NiV) is a deadly paramyxovirus capable of animal-animal and animal-human transmissions. To produce a NiV particle, the NiV matrix protein (M) must create an assembly site by binding to the surface of an infected cell and pushing the cell membrane outward for virus budding. To do so, the NiV matrix protein must co-opt or overcome an actin network underneath the cell membrane. We provide single-molecule evidence that M interacts with the actin cytoskeleton for membrane retention but not recruitment of M to existing assembly sites. This process is promoted by the Arp2/3-driven actin branching and polymerization. Our findings suggest the role of actin remodeling in NiV budding and identify a druggable site at the C-terminus of NiV-M.
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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 | 0.000 |
| 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".