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Updated: Aug 23, 2026
Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep
Published on: January 19, 2014
Linking chronic wasting disease to scrapie by comparison of Spiroplasma mirum ribosomal DNA sequences
Frank O Bastian1, Srikanta Dash, Robert F Garry
1Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA. fbastian@tulane.edu
Abstract:
Transmissible spongiform encephalopathies (TSE) are fatal neurodegenerative diseases of man and animals and are transmitted by a filterable pathogen whose identity is currently unresolved. Our data indicates that Spiroplasma, a wall-less bacterium, is involved in the pathogenesis of TSE. We searched for Spiroplasma ribosomal gene sequences in 10 scrapie-infected sheep brains and 10 normal sheep brains, 7 cervid samples infected with chronic wasting disease (CWD), and 7 normal cervid brains. DNA was extracted from these tissue samples and amplified by polymerase chain reaction (PCR) using primers specific for Spiroplasma-specific 16S rDNA. Specificity of the amplicon was determined by Southern blotting and DNA sequence analyses. Spiroplasma 16S rDNA was found in 8 of 10 scrapie-infected sheep brains and 6 of 7 CWD-infected tissue samples. All normal animal brain samples were negative. Spiroplasma 16S rDNA was also found in two human Creutzfeldt-Jakob diseased (CJD) brains but not in two age-matched normal human brains. DNA sequence analyses of the amplified PCR products from human and animal TSE cases revealed greater than 99% nucleotide sequence homology with Spiroplasma mirum. The presence of Spiroplasma DNA in TSE-infected tissues supports our hypothesis that Spiroplasma may be involved in the pathogenesis of these diseases.
Insights
Spiroplasma bacteria DNA was detected in animal and human transmissible spongiform encephalopathies (TSE) cases, suggesting its involvement in these fatal neurodegenerative diseases. This finding offers a new perspective on the cause of TSE, including scrapie, chronic wasting disease, and Creutzfeldt-Jakob disease.
Area of Science:
- Neuroscience
- Microbiology
- Pathogen Discovery
Background:
- Transmissible spongiform encephalopathies (TSE) are fatal neurodegenerative diseases affecting humans and animals.
- The causative agent of TSE remains unidentified, though it is known to be filterable.
Purpose of the Study:
- To investigate the potential role of Spiroplasma, a wall-less bacterium, in the pathogenesis of TSE.
- To detect Spiroplasma ribosomal gene sequences in animal and human TSE-affected tissues.
Main Methods:
- DNA extraction from sheep (scrapie) and cervid (chronic wasting disease - CWD) brain samples, as well as human (Creutzfeldt-Jakob disease - CJD) brain samples.
- Polymerase chain reaction (PCR) amplification using Spiroplasma-specific 16S rDNA primers.
- Southern blotting and DNA sequence analysis to confirm amplicon specificity and homology.
Main Results:
- Spiroplasma 16S rDNA was detected in 80% of scrapie-infected sheep brains and 86% of CWD-infected cervid samples.
- Spiroplasma 16S rDNA was also identified in 2 out of 2 human CJD brains, but not in any normal control tissues.
- Sequence analysis showed >99% homology between the detected Spiroplasma DNA and Spiroplasma mirum.
Conclusions:
- The presence of Spiroplasma DNA in TSE-infected tissues supports the hypothesis that Spiroplasma is involved in the pathogenesis of these diseases.
- This study provides evidence for a potential bacterial etiology in TSE, challenging the traditional prion-only hypothesis.
