Evolution of<i>Bordetella pertussis</i>and<i>Bordetella parapertussis</i>as Deduced from Comparative Genome Analyses
Bibliographic record
Abstract
The genus Bordetella contains three widely studied species: Bordetella pertussis, B. parapertussis, and B. bronchiseptica. These gram-negative coccobacilli cause respiratory disease in humans and other mammals. The significance of insertion sequence (IS) elements to the evolution of B. pertussis and B. parapertussis is discussed. The bordetellae provide an opportunity to propose hypotheses to answer questions about speciation, host restriction, and differences in genotype that could account for virulence phenotypes. This was the rationale behind the Bordetella genome sequence project in which the genome sequences of representative strains of B. bronchiseptica, B. pertussis, and B. parapertussis were generated and analyzed. The evolution of any bacterium is shaped by the selection pressures faced by the organism. The evolution of species toward causing highly contagious infections, but with a low infectivity period, from a progenitor that is much less contagious but with a very prolonged infectious period is a recurrent theme in the evolution of human pathogens. A number of putative mutations are predicted to increase the level of expression of the pertussis toxin (PT) genes in B. pertussis compared to B. bronchiseptica or B. parapertussis, and this might have contributed to the change from chronic to acute infections during B. pertussis evolution. Analysis of B. parapertussis reveals that it appears to have evolved in the face of selection pressure against the expression of factors that might be recognized by existing host immunity, but in this case directed against B. pertussis.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".