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Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep
Published on: January 19, 2014
Isolation of two distinct prion strains from a scrapie-affected sheep
Kentaro Masujin1, Yujing Shu, Hiroyuki Okada
1Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
Abstract:
We performed a transmission study using mice to clarify the characteristics of the most recent case of scrapie in Japan. The mice that were inoculated with the brain homogenate from a scrapie-affected sheep developed progressive neurological disease, and one of the scrapie-affected mice showed unique clinical signs during primary transmission. This mouse developed obesity, polydipsia, and polyuria. In contrast, the other affected mice exhibited weight loss and hypokinesia. In subsequent passages, the mice showed distinct characteristic scrapie phenotypes. This finding may prove that different prion strains coexist in a naturally affected sheep with scrapie.
Insights
This study used mice to investigate a recent Japanese scrapie case. Unique clinical signs in one mouse suggest the potential coexistence of distinct prion strains within a single sheep.
Area of Science:
- Veterinary Neurology
- Prion Diseases
- Animal Models
Background:
- Scrapie is a fatal neurodegenerative disease affecting sheep and goats.
- Understanding prion strain diversity is crucial for disease control and pathogenesis research.
- The most recent Japanese scrapie case provided an opportunity for detailed investigation.
Purpose of the Study:
- To characterize the transmissibility and phenotypic diversity of a recent Japanese scrapie isolate.
- To investigate the potential for co-circulating prion strains within a single affected sheep.
- To establish a mouse model for studying scrapie pathogenesis and strain variation.
Main Methods:
- Transmission of brain homogenate from a scrapie-affected sheep to mice.
- Monitoring of clinical signs, including neurological symptoms and metabolic changes.
- Serial passage of the agent in mice to observe phenotypic stability and evolution.
- Detailed clinical and pathological assessment of affected mice.
Main Results:
- Primary transmission to mice resulted in progressive neurological disease.
- One mouse exhibited unusual obesity, polydipsia, and polyuria, distinct from other affected mice showing weight loss and hypokinesia.
- Subsequent passages revealed distinct scrapie phenotypes, correlating with the initial observations.
- The varied phenotypes suggest the presence of multiple prion strains in the original inoculum.
Conclusions:
- The findings support the hypothesis that different prion strains can coexist within a single naturally infected sheep.
- This study provides evidence for phenotypic diversity in scrapie isolates.
- The mouse model is valuable for dissecting prion strain characteristics and their impact on disease presentation.
