A Prion Protein Gene Polymorphism at Codon 138 Modulates Chronic Wasting Disease Pathogenesis
Bibliographic record
Abstract
Prion diseases are fatal and infectious neurodegenerative diseases caused by prions. Chronic wasting disease (CWD) is a prion disease of cervids found in North America (NA), Scandinavia and South Korea. Although there are no reports of CWD in caribou (Rangifer tarandus spp.) in NA so far, previous findings show that reindeer (R. t. tarandus) are susceptible to CWD. Single amino acid substitutions (SAAS) within the cervid prion protein (PrP) sequence have been shown to prolong survival times and produce incomplete attack rates upon CWD infection. Prion protein SAAS have been found in caribou populations in NA, including a serine to asparagine substitution at codon 138 (S138N). Previous studies reported that animals harboring the N variant at this codon were either resistant or less susceptible to natural CWD prion exposure. Based on these reports, we hypothesized that the S138N PrP amino acid substitution modulates CWD pathogenesis. We report that the 138N allele frequency is rare among caribou in areas with high risk of contact with CWD-infected species, particularly in woodland caribou (R. t. caribou) herds in Saskatchewan and Alberta. We also report that the barren-ground caribou (R. t. groenlandicus) herds have higher frequencies of the 138N allele. We found that the S138N SAAS did not alter endogenous PrP properties, but rather impairs the prion conversion process. Transgenic knock-in (KI) mice expressing the 138NN PrP genotype did not develop clinical disease up to 700 days post-inoculation (dpi), whilst their wild-type deer (138SS) counter parts succumbed to CWD between ~450-580 dpi. The 138NN KI mice did, however, harbor prions capable of inducing conversion in an in vitro prion conversion assay. Remarkably, even upon intracerebral prion inoculation, seeding activity was first detected in the spleens of these KI mice. Our findings provide new insights into the role of PrP genotype in tissue tropism of prion replication. Caribou in NA are a Threatened species and an essential resource for Indigenous people. Thus, determining the mechanisms by which the 138N allele modulates CWD pathogenesis is important for future CWD management strategies, especially in areas where caribou are at a high risk of contracting the disease.
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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".