Pathogenic characteristics of an unencapsulated Streptococcus suis serotype 31 strain isolated from a patient in Thailand
Bibliographic record
Abstract
Streptococcus suis is a zoonotic pathogen that causes invasive infections in individuals who are in close contact with infected pigs or contaminated pork-derived products. An unencapsulated S. suis serotype 31 strain 43640 (sequence type 221) was first isolated from a human in Thailand in 2015; however, the mechanisms underlying host-cell interactions and virulence in animal models of this serotype are still limited. This study aimed to determine the virulence of the human unencapsulated S. suis serotype 31 strain 43640 using in vitro (A549 epithelial cells) and in vivo (C57BL/6 mouse) models. The adhesion rate of the unencapsulated strain 43640 to A549 cells was significantly lower than that of the highly pathogenic S. suis serotype 2 strain P1/7 after infection at multiplicity of infection (MOI) 1 (p < 0.01) and MOI 10 (p < 0.05). The invasion of epithelial cells by S. suis serotype 31 strain 43640 was significantly higher than that of serotype 2 strain P1/7 and the reference strain 92-4172 4 h after infection. S. suis serotypes 31 and 2 significantly induced cytotoxicity in epithelial cells by more than 50% and 90%, respectively, after 4 h and 18 h of infection. S. suis serotype 31 strain 43640 induced apoptosis in A549 cells via a caspase 9-dependent pathway. Using an in vivo mouse model, we demonstrated that S. suis serotype 31 strain 43640 induced 13.33% and 46.67% mortality due to septicemia after 24 h and 48 h, respectively. Bacterial counts in the blood of mice infected with strain 43640 were significantly lower than those in mice infected with the reference strain 12 h and 24 h after infection (p < 0.05). This study provides information on serotype 31-ST221 virulence in in vitro and in vivo models and proves that ST221 (CC221/234), an emerging human S. suis clone in Thailand, is potentially virulent.
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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".