| Encephalopathy | - damage or disease that affects the brain
- causes altered mental state, confusions, and unusual actions |
| Transmissible Spongiform Encephalopathies (TSE) | - neurodegenerative diseases of the brain
- known for at least 12 different animal species |
| Scrapies | - neurodegenerative disease in sheep
- 20 different strains recognized |
| Bovine Spongiform Encephalopathy (BSE) | - transmissible neurodegenerative disease
- impacts cattle and humans (very similar to new variant of CJF)
- first described in the UK in 1986
- 172k UK cattle cases prior to 1998
- signs: behavioral changes (poor coordination, aggression), ataxia, dementia
- 3-5 year incubation period
- confirm diagnosis with post-mortem histopathology of the brain
- changes to brain: increased vacuolation of neurons, build up of protease-resistant protein (PrP), neurons may contain fibrils of PrP |
| Kuru and Creutzfeldt-Jakob disease (CJF) | - neurodegenerative disease
- impacts humans |
| Chronic wasting disease (CWD) | - neurodegenerative disease
- impacts deer, elk, and moose |
| 3 Hypotheses for BSE | - it is a virus of which PrP is a pathogenic by-product
- it is a virino, an agent made from PrP and associated with nucleic acid
- it is a prion, a protein only infectious agent, modified form of a normal proetin ** most popular and accepted hypothesis |
| BSE Transmission | . |
| Actions in the UK to limit BSE transmission | - suspected BSE animals reported to State Veterinary Service
- movement of diseased animal, handled separately from other animals, carcasses must be incinerated
- products from animal prohibited from use in food supply chain (animal feeds, human consumption) |
| What is Kuru? | Disease in humans that was present in Papua Guinea similar to CJD. Means "to tremble with fear". Present in mostly women and children as they ate the brain/organs of tribe members who had passed away and carried the disease |
| How did British cows contract BSE? | They were fed sheep bone meal that was infected with Scrapies, and it mutated through the species barrier. |
| How did domestic cats get BSE? | Pet food made from meat of animals carrying the disease |
| What characteristics can a disease agent develop when it crosses the species barrier? | It typically becomes more virulent, can impact more species, and has a smaller incubation period |
| BSE vs. scrapie | BSE affects cows, scrapie affects sheep. BSE has a weaker species barrier, meaning it can more easily infect other species. |
| What antimicrobial treatments is BSE resistant against? | Radiation, alcohol, chemical detergents, boiling, autoclaving, UV light, proteases |
| What important contribution did J.S. Griffith make to our present knowledge of BSE? | He was a mathematician that identified 3 ways that protein alone could replicate and cause disease. |
| Who won the Nobel Prize (1997) for research work on prions? | Stanley Prusiner |
| Protein-only (prion) Hypothesis | 2 types of PrP exist in the brain. The healthy protein can be transformed into the abnormal kind via conversion. |
| How is a prion different from a normal protein (PrP) in the brain | Prion: a type of protein that can trigger normal proteins in the brain to fold abnormally, has a different shape/structure that makes it resistant to heat and other treatments. |
| How does the infectious agent for bSE cause holes in the brain? | Abnormal PrP proteins create large chains, kill brain cells, and creates holes |
| Are the holes in a BSE diseased brain visible to the unaided eye? | No, a microscope is required |
| What is the new variant CJD (nvCJD)? | Younger people weren't contraction CJD, but they were being infected with this new variant. The holes damaging the brain also appear different. |
| What are differences between prions and microorganisms such as bacteria or viruses? | Prions: protein only, no DNA or nucleic acid, microbes usually infect a cell while prions do conversion, resistant to autoclaving and radiation. |
| What actually causes death of brain neurons in BSE-infected cows? | Damage caused to brain fibers based on the manipulation of proteins |
