Evolutionary and functional connections between the typhoid toxins encoded by <i>S.</i> Typhi and <i>S. bongori</i>
Bibliographic record
Abstract
ABSTRACT The virulence properties of numerous important bacterial pathogens have been shaped by the horizontal acquisition of an AB5-type toxin. A major obstacle to the fruitful horizontal transfer of an AB5-type toxin amongst bacteria that infect divergent host species is that these toxins bind specific glycan receptors on target host cells to mediate toxin uptake, and glycosylation patterns vary substantially between different host species. In this study, we explore the evolutionary and functional connections between the related typhoid toxins that are encoded by S. enterica serovar Typhi, a human-adapted pathogen, and by S. bongori , which infects cold-blooded animals. We uncover genetic fingerprints that indicate S . Typhi’s typhoid toxin islet evolved from a larger virulence islet similar to S. bongori ’s, and show that S . Typhi’s glycan-binding PltB subunit is more similar to S. bongori PltB than it is to many diverse PltB sequence variants found in S. enterica . We further show that, surprisingly, S . Typhi strains that encode the S. bongori typhoid toxin islet intoxicate infected human epithelial cells with substantially greater potency than wild-type S . Typhi. The results of this study therefore suggest that the unexpected potency of the S. bongori typhoid toxin toward mammalian cells paved the way for sequence variants derived from this species to be acquired by - and effectively integrated into the virulence program of - the human-adapted pathogen S . Typhi.
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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 | 0.001 | 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".