Viruses Flashcards

1
Q

How small?

A

28nm-200nm

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2
Q

How many types of nucleic acid?

A

One

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3
Q

Types of nucleic acid available in viruses

A

ss DNA, ds DNA, ss RNA, ds RNA

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4
Q

DNA viruses have what nucleic acid type?

A

ssDNa or ds DNA

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5
Q

RNA viruses have what nucleic acid type?

A

ssRNA or dsRNA

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6
Q

Retroviruses have what type of nucleic acid?

A

ssRNA

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7
Q

Hepadnaviruses have what type of nucleic acid?

A

dsDNA

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8
Q

Describe the structure of a virus

A

Protein coat (Capsid) made up of capsomeres which are units of the icosahedron
Nucleic acid core - two geomatric forms - Icosadehral or helical
Can have envelopes
Can have tails

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9
Q

Envelopes on viruses can..

A

produce immune response

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10
Q

Describe icosohedral structure

A

20 triangular faces, 30 sides, 12 vertices
Capsomeres: pentons or hexons
Very efficient protein expression as little/no waste of space

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11
Q

What is a bacteriophage? What is their structure like? What are they used for?

A

Virus of bacteria - helical structure - used to study bacterial genetics

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12
Q

How to culture bacteriophage viruses?

A

1) pour mixture of molten top agar, bacterial cells and diluted phage suspension onto a solidified nutrient agar plate
2) Let it solidify
3) Sandwich of top agar and nutrient agar forms
4) Incubate
5) Should have phage plaques and a lawn of host cells

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13
Q

How do viruses replicate?

A

1) Attachment (adsorption)
2) Penetration (injection) but protein coat remains outside
3) Synthesis of nucleic acid and protein
4) Assembly and packaging
5) Release (lysis)
6) Virions produced

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14
Q

Viruses need host cells because..

A

They do not have their own cellular machinery, i.e. they can’t make proteins or ATP or metabolise by themselves and hence are not living organisms

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15
Q

In order, what is produced when viruses try to replicate?

A

Eclipse: Early enzymes, nucleic acid, protein coats
Maturation: Assembly and release then occurs

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16
Q

How are viruses transmitted? Give an example of a specific virus for each method of transmission.

A
Respiratory - influenza A
Faecal-oral - Enterovirus and Polio 
Blood-borne - Hepatitis B,C and HIV 
Sexual transmission - HIV
Animal or insect vectors - Rabies virus, Zeka virus
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17
Q

What is a virus tissue tropism?

A

Its favourite place to effect

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18
Q

Which specific type of immune system cells detect HIV?

A

CD4+ cells

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19
Q

What acts as the receptor for poliovirus?

A

CD155

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20
Q

List some in vivo disease processes caused by viruses

A
cell destruction
virus-induced changes to gene expression (eg HPV)
Immunopathogenic disease (eg HIV)
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21
Q

Acute virus infections are…

A

localised to a specific site of the body

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22
Q

What is viraemia?

A

When the virus is in the blood. This can cause widespread infection of tissues

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23
Q

Properties of Influenza A virus?

A
  • Myxovirus
  • Enveloped virus
  • Segmented RNA genome
  • Infects a wide range of animals other than humans (pigs, birds etc)
  • Undergoes extensive antigenic variation
  • Major cause of respiratory infections
24
Q

Describe an influenza A infection. How is it spread? Where does it infect?

A

Spread by respiratory route.
Virus infects cells of respiratory epithelium
Destruction of respiratory epithelium occurs, which may cause secondary bacterial infections
Altered cytokine expression leading to fever e.g. interleukin-1 and interferon

25
Q

Retrovirus

A

HIV

26
Q

Myxovirus

A

Influenza

27
Q

Rhinovirus

A

Common cold

28
Q

Reovirus

A

Various

29
Q

Picornavirus

A

Polio

30
Q

Herpesvirus

A

Varicell zoster and herpes

31
Q

Paramyxovirus

A

Measles, rubella

32
Q

Adenovirus

A

Tonsilitis

33
Q

Poxvirus

A

Smallpox

34
Q

List viruses controlled by current antiviral therapy

A
Cytomegalovirus (CMV)
Hepatitis viruses
Herpes viruses
HIV
Influenza viruses
Respiratory syncytial virus (RSV)
35
Q

Name some key characteristics of antiviral drugs

A
  • able to enter the cells infected with the virus
  • interfere with viral nucleic acid synthesis and/or its regulation
  • some drugs interfere with ability of virus to bind to cells
  • some drugs stimulate the body’s immune system
36
Q

Best responses to antiviral drugs are?

A

In patients with competent immune systems as this works synergistically with the drug to eliminate or supress viral activity

37
Q

Antiviral drugs treat

A

infections caused by viruses other than HIV

38
Q

Antiretroviral drugs treat

A

Infections caused by HIV

39
Q

HSV1 treats

A

Herpes Simplex Virus

Oral herpes

40
Q

HSV2 Treats

A

Herpes Simplex Virus

Genital herpes

41
Q

Medications for the varicella zoster virus treat

A

chickenpox and shingles

42
Q

Amantadine (Symmetrel) is active against

A

Influenza A

43
Q

Amantadine is used when?

A

Prophylatically when a vaccine is not available or cannot be given

44
Q

Amantadine can reduce recovery time. Give the CNS side effects.

A

insomnia, nervousness, lightheadedness

45
Q

Amantadine GI side effects?

A

anorexia, nausea etc

46
Q

What type of drug is Acyclovir (Zovirax)

A

Synthetic nucleoside analog

47
Q

Acyclovir suppresses the replication of which viruses?

A

HSV1, HSV2, VZV (Varicella)

48
Q

What formulations of Acyclovir are available?

A

Oral, topical and parenteral forms

49
Q

What are nonretroviral neuraminidase inhibitors (NNIs) used for?

A

Stopping the flu virus from replicating and to reduce the overall duration of illness.

50
Q

Oseltamivir is a NNI with what side effects?

A

nausea, vomiting

51
Q

Zanamivir is a NNI with what side effects?

A

diarrhoea, nausea, sinusitis

52
Q

When should NNI treatment occur?

A

within 2 days of influenza symptom onset

53
Q

What does HAART stand for? What is it?

A

Highly active antiretroviral therapy. It includes at least 3 medications and they work in different ways to reduce the viral load

54
Q

What is an RTI drug? How do they work?

A

Reverse transcriptase inhibitors. Block activity of the enzyme reverse transcriptase, preventing production of new viral DNA

55
Q

Give 3 types of RTI subclasses

A
Nucleoside RTIS (NRTIs)
Nonnucleoside RTIs (NNRTIs)
Nucelotide RTIs (NTRTIs)
56
Q

Give examples of RTIs

A
Abacavir
Didanosine
Stavudine
Delavirdine
Lamivudine
Tenofovir