Viruses Flashcards

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1
Q

what are the general properties of viruses

A

they are of a small size, and their genome can be composed of either RNA or DNA. they are metabolically inert and do not possess ribosomes. some have enzymes. not able to carry out protein synthesis on their own.

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2
Q

why are viruses important clinically

A

in relation to disease obviously but also when considering taking samples as we have to use different types of swabs and cells to grow the viruses rather than agar because they can’t grow on their own

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3
Q

which microbes can be grown on agar plates

A

bacteria and fungi

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4
Q

are all viruses the same size

A

no there are variations

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5
Q

what is a virion

A

a complete virus particles

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6
Q

what do virions compose of

A

substructures, such as lipid membranes and capsids

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7
Q

what are capsids

A

protein shell in the centre of viruses

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8
Q

how does herpes simplex virus appear on electron micrographs

A

fried egg

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9
Q

why are viral capsids important structures

A

they protect the nucleic acid genome which can be RNA or DNA

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10
Q

what are the stages to viral replication

A
  • attachment
  • penetration
  • uncoating
  • synthesis of viral components
  • assembly
  • release
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11
Q

what are the different effects that viruses can have on cells

A

cytopathic
transformation
latent infection

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12
Q

what is cytopathic infection

A

this is when the virus causes the cell to die

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13
Q

what is an example of a virus causing a cytopathic effect in its target cell

A

herpes simplex one and its effect on oral mucosa epithelial cells

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14
Q

what is transformation as an effect of viruses on cells

A

the cell has not been killed but has been changed to a cancerous cell

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15
Q

what is an example of cell transformation as a result of viral infection

A

papilloma virus and oral cancer

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16
Q

what is latent infection

A

this is where the virus or elements of the viral nucleic acid remain in the cell with no obvious effects on cell function

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17
Q

what are some viruses that cause latent infection

A

recurrent herpes labialis and herpes simplex

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18
Q

what are some diseases that viruses are responsible for

A

AIDS and the flu

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19
Q

how do viruses produce proteins

A

they take over the operation of cells to manufacture new viruses

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20
Q

what must the virus first do in order to produce proteins in the host cell

A

the virus must gain access and convince the machinery to make multiple copies of it

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21
Q

are viruses specific

A

yes

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22
Q

how is the specifity of viruses achieved

A

through the receptors on the membrane of the cell which the viruses use to target their specific cells for infection

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23
Q

why can viral DNA be described as simple

A

only contains the genetic information to manufacture new virus parts

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24
Q

what happens once the virus has entered the cell and released its DNA into the nucleus

A

transcribed to RNA and the protein machinery of the host will translate the instructions into new components of a virus. these parts are assembled in the host cell and emerge when ready. this usually kills the cell.

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25
Q

what can some viruses retain following replication within the host cell.

A

parts of the host cell membrane to form an envelope to protect from the immune system of the host organism.

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26
Q

what do anti viral drugs target

A

specific points in the viral life cycle to prevent it from replicating

27
Q

what are the different modes of transmission for viruses

A

inhalation
ingestion
inoculation
congenital
sexual transmission

28
Q

what is the inhalation mode of transmission

A

infection via the respiratory tract

29
Q

what is an example of a virus that relies on inhalation

A

coronavirus

30
Q

how does ingestion work as a mode of transmission

A

via the gastrointestinal tract

31
Q

what is example of a virus that requires ingestion

A

norovirus

32
Q

what is inoculation as a mode of transmission

A

this can be subdivided as entry via skin abrasions, mucous membranes, blood transfusions, injection, organ transplants and bites

33
Q

what is an example of a virus that is transmitted via inoculation

A

hepatatis B transmission

34
Q

what is congenital mode of transmission

A

from the mother to the fetus

35
Q

what is an example of a virus that relies on congenital modes of transmission

A

rubella viral infection

36
Q

what is an example of a virus that is sexually transmitted

A

HIV

37
Q

what disease can affect the nervous system

A

rabies

38
Q

which disease can affect the respiratory tract

A

adenovirus

39
Q

what is an example of a localised disease of the skin and mucous membranes

A

herpes simplex infection

40
Q

what is an example of a virus affecting the eye

A

adenovirus

41
Q

what is an example of a virus affecting the liver

A

hepatitis C

42
Q

what is an example of a virus affecting the salivary glands

A

mumps

43
Q

what is an example of a virus affecting the gastrointestinal tract

A

norovirus

44
Q

what is an example of a virus affecting the reproductive system

A

HIV

45
Q

what is hepatitis

A

inflammation of the liver that can be caused by excessive alcohol consumption or through viral infection

46
Q

what is hepatitis A

A

actute infection, transmitted through contaminated food and water, or through unprotected sex and sharing syringes

47
Q

what is hepatitis C

A

chronic and long lasting, blood borne. children can get it from their mother if she had it while carrying. caused by sharing needles, nail clippers, tooth brushes or razors.

48
Q

does hepatitis C have symptoms

A

no

49
Q

what is hepatitis B

A

can be acute or chronic depending on age when transmitted. unprotected sex and sharing needles

50
Q

why is it important to use viral diagnostics

A

diagnosis can lead to treatment

51
Q

when is anti viral drug susceptibiliy important to consider

A

when managing conditions like HIV

52
Q

which fields are coronavirus and influenza viral diagnostics important to consider

A

epidemiology and surveillance

53
Q

what are the clinical primers for viral diagnostics

A
  • clinical history and examination
  • use a systems based approach
  • surgical seive to consider what the diagnosis could be
  • make a provisional diagnosis
  • plan special investigations
  • wide range of specimens to take
54
Q

how often can virology lab manuals change

A

every six months

55
Q

what are the different specimens to take

A
  • swabs
  • faeces
  • aspirates
  • plasma
  • CSF
  • vesicle fluids
  • urine
56
Q

what is an example of a virus where nucleic acid detection would be used

A

herpes simplex virus

57
Q

what can plasma be used for

A

monitoring polymerase chain reaction like HIV load

58
Q

what can serum be used for

A

serological diagnosis for hepatitis B where you are looking for antibody titres

59
Q

what is the test for influenza based on

A

RNA - take small amounts of nucleic acid and multiply it into large amounts to enable that to quantified and more readily detected

60
Q

what kind of virus is influenza

A

RNA

61
Q

why is it important to consider influenza being an RNA virus

A

must be reverse transcribed before carrying out the polymerase chain reaction

62
Q

how is antigen detection carried out

A

from blood serum, the surface antigen is detected

63
Q

what can be used to distinguish the time course of a viral infection

A

the first class of antibody produced during acute phasing of an infection is IgM and two weeks later there is a change in class to IgG which can be used to distinguish the time course of a viral infection

64
Q
A