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level: L16 Bovine Spongiform Encephalopathy (BSE)

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level questions: L16 Bovine Spongiform Encephalopathy (BSE)

QuestionAnswer
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. scrapieBSE 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) Hypothesis2 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 brainPrion: 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