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Prions are a type of protein that may cause disease in animals and humans by causing usually healthy proteins in the brain to fold abnormally.
- Prions have a totally different mechanism of action than bacteria and viruses since they are simply proteins with no genetic information.
- Once a misfolded prion enters a healthy individual, possibly through infected food, it changes correctly folded proteins into the disease-associated form.
- Stanley B. Prusiner coined the term 'prion' in 1982.
- They do not contain nucleic acids and are contagious, but smaller than viruses.
- They are rod-shaped proteins that are found in neurons.
- Prions cause alterations in typical folded proteins.
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Key Terms: Prions, Disease, Protein, Nucleic acids, Transmissible spongiform encephalopathies, Infections, Tissue, Virus, Germs, Creutzfeldt-Jakob Disease
What are Prions?
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Prions are infectious agents that have long challenged our basic biological assumptions. They have the appearance of other infectious creatures, yet they lack any of the most basic characteristics of organisms.
- They are genetically deficient in particular (DNA or RNA).
- Prions research has led to the conclusion that the "infectious agent" is a misfolded protein that causes a normal cellular protein to alter its shape and become misfolded.
- Prion diseases are extremely rare and difficult to spread as diseases.
- However, because they are progressive neurodegenerative illnesses with no cure or treatment, they are exceedingly frightening.
- Due to a lack of understanding of what prions are and how they act, they also have a mystique of being weird.
- Furthermore, the prion's action is unlike that of any germ or virus.
- The reason for this is that it is simply protein without any genetic material.
- When a misfolded protein enters the human body, it has an unfavorable effect on the correctly folded protein.
- Furthermore, Stanley B. Prusiner and his colleagues discovered the prions in the early 1980s.
- The term prion comes from the phrase "proteinaceous infectious particle."
- Infection allows this misfolded protein to enter a human or animal's brain.
- It can also be caused by a mutation in the gene that codes for protein.
- However, scientists have yet to fully comprehend the mechanism.
Prions
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What is a Prion Infection?
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Prion infection, often known as transmissible spongiform encephalopathies (TSE), is a type of neurodegenerative disease that affects a small number of people.
- It affects both people and animals' brains.
- TSEs are also caused by prions, which are the causal agents.
- This aberrant protein folding, in particular, can cause brain injury, which is usually deadly.
Structure of Prions
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Prions can be found all over the body, but those that cause sickness have a distinct structure. Few of them are even protease-resistant. The two prions isoforms are:
PrPc
These prion proteins reside on the cell membrane and are involved in cell signaling and cell adhesion. More research is being done to learn more about its functions.
PrPsc
This is the disease-causing prion, which is protease-resistant. It affects PrPc confirmation and modifies it.
- It's thought that they have more beta sheets than alpha-helices.
- It also produces amyloid filaments with a complex structure.
- Other free proteins bind to the ends of these fibers as well.
- Prions with comparable amino acids can only bind to each other.
- Cross-species binding is feasible, although it is extremely unusual.
Types of Prion Disease
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There are three types of Prion disease i.e. acquired, sporadic, or genetic.
Acquired Prion Disease
When a person is exposed to an infectious protein, they get prion diseases. Although frightening, these prions are rarely caught by humans. For example, in kuru diseases, prions were transferred to humans through cannibalism. Its primary source was New Guinea pigs.
Genetic Prion Disease
Familial prion diseases are caused by genetic transmissions. However, it is not always inherited from the ancestors. It may be caused by a mutation in certain DNA.
Sporadic Prion Disease
Prion disease is also thought to be sporadic. This signifies that the reason has not been identified. This type of prion disease is the most common to date.
Causes of Prion Disease
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The following are the causes of Prion disease
- Prion disease can be passed down through the generations. People who have a family history of the disease are more likely to develop the mutation.
- Prion disease affects older persons on a random basis.
- Furthermore, this disease can be transmitted by consuming contaminated animal products with an altered prion structure.
- Last but not least, it is disseminated due to the use of contaminated medical equipment.
- A medical operation involving contaminated tissue, such as a dura mater graft or cornea transplant, can also spread it.
Symptoms of Prion Disease
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Prion disease has a long, often years-long incubation phase. Symptoms, on the other hand, worsen over time and can be quite severe. The following are some of the most prevalent symptoms of this disease:
- Agitation, depression, and other personality changes are examples of personality changes.
- Dementia that is rapidly progressing
- Disorientation
- Uncontrollable muscle spasms
- Insomnia
- Coordination problems
- Hallucinations
- Fatigue
- Speaking difficulties
- Blindness
Transmission of Prion Disease
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Humans have been diagnosed with several prion disorders. Creutzfeldt-Jakob Disease, sometimes known as CJD, is the most frequent. It occurs once a million times every year, making it a rare but not unknown disease.
- It appears to be the result of a chance occurrence of the normal prion protein misfolding into the disease form.
- It's possible that something starts the sickness, but there's no evidence to support this theory so far.
- This "background" CJD, which appears to be spontaneous, is also referred to as "sporadic CJD," or sCJD.
- Prion disease has been observed to run in families in a small number of cases.
- The family possesses a mutant variant of the prion gene, according to modern research.
The mutation appears to increase the likelihood of the disease version of the prion developing. As a result, there are three major "causes" of prion disease:
- Obtaining a faulty prion from the outside
- Spontaneous or sporadic prion illness caused by one's prion protein
- Genetics: having a higher probability of developing the disease form of one's prion protein.
Diagnosis of Prions Disease
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Doctors utilize a variety of tests to diagnose Prion Disease, including:
- An MRI scan is used to examine the brain.
- Analyze brain waves with an electroencephalogram.
- Fluid samples from the spinal cord are collected.
- Tests on the blood
- Exams of the eyes and the nervous system are used to diagnose vision loss and nerve injury.
Treatment of Prion Disease
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The short answer is that there is no available medication or cure.
- As our understanding of the prion grows, researchers are working to develop agents that can interfere with the "bad" form's creation or function, or even "dissolve" preexisting prion material.
- There is some intriguing research, as well as some promising anecdotal evidence.
- However, no treatment has been verified by proper testing so far.
- It's extremely difficult to test an agent against prion disease in humans.
- For one thing, such illnesses are uncommon.
- Furthermore, much of the lab work shows that treatment would be most beneficial early in the course of the disease; yet, in humans, identification of prion diseases is frequently done after the disease has progressed.
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Things to Remember
- Prions are infectious agents lacking the characteristics of organisms.
- Prion infection is often known as transmissible spongiform encephalopathies (TSE).
- It is a type of neurodegenerative disease that rarely affects people.
- Some prions are even protease-resistant.
- Prions can be transmitted by consuming contaminated animal products with an altered prion structure.
- Prion disease has a long, often years-long incubation phase.
- There are three types of Prion disease i.e. acquired, sporadic, or genetic.
Sample Questions
Ques. How can we prevent prions? (2 Marks)
Ans. Cleaning and sanitizing medical equipment properly may help to prevent the disease from spreading. Don't donate organs or tissue, especially corneal tissue, if you have or suspect you have CJD. New laws governing the handling and feeding of cows may aid in the prevention of prion disease spread.
Ques. Has anyone survived prion disease? (2 Marks)
Ans. A Belfast man who died 10 years after contracting variant CJD, the human form of mad cow disease, has died. Doctors were perplexed when Jonathan Simms became one of the world's oldest survivors of the condition. Jonathan, a gifted footballer, became ill for the first time in May 2001.
Ques. What is a Prion? (2 Marks)
Ans. A prion is a rare type of normally innocuous protein that is found in the brain. This protein is linked to a variety of human and animal neurodegenerative disorders. It is not, however, a virus or bacterial infection, but rather a protein failure.
Ques. What is Prion Biology? (2 Marks)
Ans. Prion biology is the study of this highly complex disease, which has a long incubation time, spreads quickly, and has long-term consequences. Presently there is no cure for this condition. Medication can only be used to keep it under control.
Ques. What are the diseases that are caused by Prions? (2 Marks)
Ans. CJD, kuru, fatal insomnia, variably protease-sensitive prionopathy, and Gerstmann-Sträussler-Scheinker disease are just a few of the disorders caused by prions. This condition is sporadic and inherited, to be sure.
Ques. How is a prion contracted? (2 Marks)
Ans. CWD proteins (prions), according to scientists, are communicated between animals through body fluids like feces, saliva, blood, or urine, either directly or indirectly through soil, food, or water contamination.
Ques. How long can you live with prion disease? (1Mark)
Ans. The majority of patients die within 4 to 2 years. Electroencephalography, cerebrospinal fluid studies, and magnetic resonance imaging are frequently used to confirm the diagnosis.
Ques. What kills a prion? (1 Mark)
Ans. The most effective technique of disposal for prion-contaminated material is incineration. Although prion infectivity can be destroyed by burning at 1,000°C, low infectivity can be maintained following treatment at 600°C.
Ques. Can the body fight prions? (2 Marks)
Ans. Immune system cells enhance prion multiplication and/or facilitate neuroinvasion in healthy people. Immune manipulation methods aiming at inhibiting the spread of infectious pathogens to the central nervous system could be developed with a better understanding of these characteristics of prion disorders.
Ques. What are the early signs of CJD? (3 Marks)
Ans. Early neurological symptoms of sporadic CJD include:
- difficulties walking due to balance and coordination issues.
- speech that is slurred
- a feeling of numbness or pins and needles in many regions of the body
- dizziness.
- Double vision is an example of a visual problem.
- Hallucinations (seeing or hearing things that aren't actually there) are a type of hallucination.
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