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Introduction – Prions

by Vincent Racaniello, PhD
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    00:01 Hello and welcome to Prions. After hearing this lecture, not only will you not want to eat meat any longer, but more importantly you should know the history of prion discovery.

    00:14 You should understand what prions are and what diseases they cause. You'll know that there are three different types of prion diseases and you'll begin to understand the threat of mad cow disease and chronic wasting disease to the food supply.

    00:33 The diseases caused by prions are called transmissible spongiform encephalopathies. Let's take that word apart, because it's quite long. An encephalopathy is a disease of the brain, and as you'll see in a moment, spongiform reflects the kind of changes caused in the brain and transmissible means that they can be infectious. So transmissible spongiform encephalopathies or TSEs; these are fatal neurodegenerative disorders of animals. They're uniformly fatal and they cause changes to your neurological system. Thousands of human are diagnosed with TSCs each year and about 1% of them arise by infection. We will talk about how the others are acquired as well. And as an example of a TSC, by 2002, 120 humans had contracted Creutzfeldt-Jacob disease from eating contaminated meat from animals with BSE, which stands for bovine spongiform encephalopathy. The TSC diseases affect many different animal species, we recognize TSEs of animals, so for example, bovine spongiform encephalopathy or BSC, mad cow disease, affects cows. Chronic wasting disease or CWD is a prion disease of deer, elk and moose.

    02:06 Exotic ungulate encephalopathy affects wild game like nyala and greater kudu, and there are also diseases of cats, feline spongiform encephalopathy. We also recognize human TSC diseases, for example Creutzfeldt-Jacob disease, fatal familial insomnia, Gerstmann-Straussler syndrome, Kuru and Variant CJD, all of these animal and human TSEs are caused by prions.

    02:42 Why are these so serious? Why do we give an entire lecture to prion diseases? Well they are uniformly undetectable before symptoms develop, we have no diagnostic tests yet that can tell if you are infected with a prion. They can't be treated, so once you have symptoms, you are going to die, because we can't make you feel better and we can’t prevent your death and they're invariably fatal. They involve an incubation period and symptoms which involve neurological problems, and they all lead to death. So they're rare, but they are very serious diseases.

    03:22 Part of the name TSE contains spongiform, so let's explore that. Spongiform comes from the fact that the infected brain has holes throughout it. This is a section of brain from a sheep with a TSE with a prion disease and you can see little holes in the brain and that's why it's called spongiform. All of these diseases are associated in human with severe psychomotor dysfunction, and the exact symptom depends on which part of the brain is damaged, it can be different for the different prion diseases. Each disease in fact, Creutzfeldt-Jacob, Gerstmann Straussler, etc. has a distinct symptom pattern and pathology associated with it, but of course they all involve the brain and spinal cord.


    About the Lecture

    The lecture Introduction – Prions by Vincent Racaniello, PhD is from the course Microbiology: Introduction.


    Included Quiz Questions

    1. Kuru
    2. Chronic wasting disease
    3. Exotic ungulate encephalopathy
    4. Feline spongiform encephalopathy
    1. 3
    2. 1
    3. 2
    4. 4
    5. 5
    1. Brain
    2. Lungs
    3. Liver
    4. Intestine
    5. Heart
    1. At first symptom appearance
    2. Once symptoms resolve
    3. At first exposure
    4. During secondary infections
    5. At the time of initial infection

    Author of lecture Introduction – Prions

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD


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