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A prion / ˈ p r iː ɒ n / ⓘ is a misfolded protein that induces misfolding in normal variants of the same protein, leading to cellular death.Prions are responsible for prion diseases, known as transmissible spongiform encephalopathy (TSEs), which are fatal and transmissible neurodegenerative diseases affecting both humans and animals.
Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, [1] are a group of progressive, incurable, and fatal conditions that are associated with the prion hypothesis and affect the brain and nervous system of many animals, including humans, cattle, and sheep.
A human pathogen is a pathogen (microbe or microorganism such as a virus, bacterium, prion, or fungus) that causes disease in humans. The human physiological defense against common pathogens (such as Pneumocystis ) is mainly the responsibility of the immune system with help by some of the body's normal microbiota .
Diseases in humans that are caused by infectious agents are known as pathogenic diseases. Not all diseases are caused by pathogens, such as black lung from exposure to the pollutant coal dust , genetic disorders like sickle cell disease , and autoimmune diseases like lupus .
Creutzfeldt–Jakob disease (CJD), also known as subacute spongiform encephalopathy or neurocognitive disorder due to prion disease, is a fatal neurodegenerative disease. [ 4 ] [ 1 ] Early symptoms include memory problems, behavioral changes, poor coordination, and visual disturbances. [ 4 ]
Others insert additional amino acids into the protein or cause an abnormally short protein to be made. These mutations cause the cell to make prion proteins with an abnormal structure. The abnormal protein PrP Sc accumulates in the brain and destroys nerve cells, which leads to the mental and behavioral features of prion diseases. [citation needed]
Factors which have been identified as impeding the identification of pathogens include the following: 1. Lack of animal models: Experimental infection in animals has been used as a criterion to demonstrate a disease-causing ability, but for some pathogens (such as Vibrio cholerae, which causes disease only in humans), animal models do not exist.
[30] [31] In this way, the disease state can be brought about in a susceptible host by the introduction of diseased tissue extract from an affected donor. The best known forms of inducible proteopathy are prion diseases, [32] which can be transmitted by exposure of a host organism to purified prion protein in a disease-causing conformation. [33 ...