Proteinacious infectious particle

VOCABULARY LIST TO TEXT A

abnormally folded (protein)	[æb'nɔːm(ə)lɪfəuldɪd]	(белок) с аномальной третичной структурой
bodilyadj	['bɔdɪlɪ]	телесный
cannibalismn	['kænɪb(ə)lɪz(əm]	каннибализм, людоедство
cellularadj	['seljulə]	клеточный
deficiencyn	[dɪ'fɪʃ(ə)n(t)sɪ]	здесь: недостаточность
encephalopathy n	[еnˌsеfəˈlɒpəθɪ]	энцефалопатия
faultyadj	['fɔːltɪ]	поврежденный
inheritedadj	[ɪn'herɪtɪd]	наследственный
ionizingadj	['aɪənaɪzɪŋ]	ионизирующий
neurodegenerativeadj	[njuərɔdɪ'ʤen(ə)rətɪv]	нейродегенеративный
particlen	['pɑːtɪkl]	частица
prion n	['praɪən]	прион
proteinaceous adj	['prəutiːnеɪ'ʃəs]	белковый
replicatev	['replɪkeɪt]	воспроизводиться
spongiform adj	['spʌnʤɪˌfɔːm]	губчатый
templaten	['templeɪt]	образец, шаблон
triben	[traɪb]	племя
triggerv	['trɪgə]	здесь: запускать
ultravioletadj	[ˌʌltrə'vaɪələt]	ультрафиолетовый
vacuolen	['vækjuəul]	вакуоль

The term “prion” is derived from proteinacious infectious particle and refers to the pathogen that causes transmissible spongiformencephalopathies (TSEs).

This small infectious particle is a disease-causing form of a protein called cellular prion protein (PrPc). PrPc is mainly found on the surface of cells in the central nervous system, but it is also located in other bodily tissues. Although the specific role of PrPc is not clear, studies suggest that this protein plays a protective role in cells and helps them respond to oxygen deficiency.

A prion is composed of abnormally folded protein that causes progressive neurodegenerative conditions, with two of the most notable being Bovine spongiform encephalopathy (BSE or mad cow disease) seen in cattle and livestock and Creutzfeldt-Jakob disease (CJD) seen in humans. The faulty prions replicate and convert other proteins, in a chain reaction. The abnormal prions have a different shape compared to the normal protein; this makes it more difficult for the body to break them down, so they accumulate in the brain.There they affect the brain structure by acting as a template, inducing proteins with normal folding to convert to the abnormal prion form.The nerve cells of the brain are eventually damaged and lost, which causes tiny vacuoles to form in the brain. These give the brain a sponge-like appearance under the microscope, hence the term spongiform disease.

There are different types of prion diseases. Some can be inherited, while others occur by chance through a genetic mutation, and others are passed on to other individuals during medical procedures using contaminated equipment or body parts, or through eating contaminated food. The disease can take years to develop.

Prions are so small that they are even smaller than viruses and can only be seen through an electron microscope when they have aggregated and formed a cluster. Prions are also unique in that they do not contain nucleic acid, unlike bacteria, fungi, viruses and other pathogens. Prions are therefore resistant to procedures that destroy pathogens by breaking down nucleic acid. Furthermore, these particles are an abnormal version of a normal protein that is already coded for in the body, they do not trigger a host immune response, as other pathogens do. Cellular enzymes referred to as proteases can break down the normal protein, but prion proteins are resistant to this and subsequently accumulate in the brain tissue as they replicate.

The prion diseases were originally discovered by Dr Gajdusek. The first disease discovered was Kuru, which was affecting native tribes in the Papua New Guinea highlands in the 1950s. The prions in Kuru were actually transmissible and had probably been transmitted as a result of the cannibalism rituals the tribes used to perform.

In the late1960's, research showed that the agent causing sheep TSE or scrapie was highly resistant to being deactivated by ultraviolet and ionizing radiation therapies that would usually destroy any pathogens that contained nucleic acid. However, the nature of these particles was still unclear and scientists made various suggestions including proteins, membrane fragments, small DNA viruses and polysaccharides.

Some researchers decided that whatever the nature of the agent was, it did not depend on nucleic acid to reproduce. In 1982, StanleyPrusiner from the University of California in San Francisco published an article in “Science”, demonstrating isolation of scrapie agent, which he called “prion” (term derived from “protaneiceous infectious particle”).In 1997,Prusiner was awarded the Nobel Prize for his prion research.

Notes

Creutzfeldt&Jakob disease ['krutsfeld n 'ʤeɪkəbdɪ'ziːz] – болезньКрейтцфельдаиЯкоба;

Hans Creutzfeldt [hænz'krutsfeld] –ГансКрейтцфельдт;

AlfonsJakob [ælfons'ʤeɪkəb] –АльфонсЯкоб;

Carleton Gajdusek ['kʌrltən 'gaɪdəʃek] – КарлтонГайдузек;

Stanley Prusiner['stænlɪ'pruzɪner] – СтенлиПрузинер.

Exerise 1. Trace the development of prion study, make up a short talk.

Exerise 2. a) Make up collocations using words from both columns.

chain	mutation
genetic	encephalopathies
ionizing	reaction
spongiform	enzymes
cellular	radiation

b) Fill in the gaps with the collocations from above.

1.The term “prion” is derived from proteinacious infectious particle and refers to the pathogen that causes transmissible … (TSEs).

2. The faulty prions replicate and convert other proteins, in a… .

3. Some can be inherited, while others occur by chance through a … , and others are passed on to other individuals during medical procedures using contaminated equipment or body parts, or through eating contaminated food.

4. … referred to as proteases can break down the normal protein, but prion proteins are resistant to this and subsequently accumulate in the brain tissue as they replicate.

5. In the late1960's, research showed that the agent causing sheep TSE or scrapie was highly resistant to being deactivated by ultravioletand … therapies that would usually destroy any pathogens that contained nucleic acid.