The <i>Campylobacter jejuni</i> helical to coccoid transition involves changes to peptidoglycan and the ability to elicit an immune response
Bibliographic record
Abstract
Campylobacter jejuni is a prevalent enteric pathogen that changes morphology from helical to coccoid under unfavorable conditions. Bacterial peptidoglycan maintains cell shape. As C. jejuni transformed from helical to coccoid, peptidoglycan dipeptides increased and tri- and tetrapeptides decreased. The DL-carboxypeptidase Pgp1 important for C. jejuni helical morphology and putative N-acetylmuramoyl-L-alanyl amidase AmiA were both involved in the coccoid transition. Mutants in pgp1 and amiA showed reduced coccoid formation, with ∆pgp1∆amiA producing minimal coccoids. Both ∆amiA and ∆amiA∆pgp1 lacked flagella and formed unseparated chains of cells consistent with a role for AmiA in cell separation. All strains accumulated peptidoglycan dipeptides over time, but only strains capable of becoming coccoid displayed tripeptide changes. C. jejuni helical shape and corresponding peptidoglycan structure are important for pathogenesis-related attributes. Concomitantly, changing to a coccoid morphology resulted in differences in pathogenic properties; coccoid C. jejuni were non-motile and non-infectious, with minimal adherence and invasion of epithelial cells and an inability to stimulate IL-8. Coccoid peptidoglycan exhibited reduced activation of innate immune receptors Nod1 and Nod2 versus helical peptidoglycan. C. jejuni also transitioned to coccoid within epithelial cells, so the inability of the immune system to detect coccoid C. jejuni may be significant in its pathogenesis.
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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".