Microbio Chapter 13- Viruses Flashcards

1
Q

What is a virus?

A

Obligate parasites

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2
Q

What is a virion?

A

Fully developed, infective form of a virus outside a host cell

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3
Q

A virion contains?

A

A genome
A capsid
An envelope
Spikes

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4
Q

How can virus parasites be transmitted?

A

Birds, bats, humans, swine
-They act as mixing vessels for genes

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5
Q

What genome does a virion have?

A

DNA or RNA

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6
Q

What is a capsid?

A

A protein coat
Made from subunits called Capsomeres

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7
Q

What are the functions of a capsid?

A
  1. Used for identification (Gives cell a unique shape)
  2. Used for transmission to the hosts
  3. Used for attachment + protection
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8
Q

What covers the capsid?

A

The envelop

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9
Q

Do all viruses have an envelop?

A

No some can be non-enveloped

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10
Q

What is the envelop made of?

A

A phospholipid bilayer, proteins and crabohydrates

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11
Q

What is the envelop’s function?

A

Protection

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12
Q

What are a viruses spikes made from?

A

Protein and carbohydrates

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13
Q

What are the types of spikes?

A

Hemagglutination spike (HA)
Neuraminidase spike (NA)

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14
Q

What shape is a Hemagglutination spike?

A

Cone (triangular)

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15
Q

What shape is a Neuraminidase spike?

A

Bulb (circular)

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16
Q

What is the function of HA spikes?

A

Kills blood cells and penetrate the cell
-Can also be used to recognise the virus

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17
Q

What is the function of NA spikes?

A

Separate the virion from the host cell after infection

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18
Q

What part of the virus do some vaccines target?

A

The spike protein
e.g; Covid-19 mRNA vaccine

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19
Q

What do the letters and numbers in H1N1 mean?

A

H- Hemagglutionation
N- Neuraminidase
The numbers represent how many mutations each protein spike has undergone

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20
Q

What happens to a virus the more it mutates?

A

It gets more infectious

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21
Q

What does HIV stand for?

A

Human Immunodeficiency Virus

22
Q

What does HIV target?

A

T- helper cells and CD4 receptors

23
Q

What genome does an HIV virion have?

A

RNA
-Single stranded

24
Q

What does an HIV virion have?

A

Genome
Capsid
Envelope
Glycoprotein spike

25
Q

What kind of virus is HIV?

A

Retrovirus

26
Q

What is a retrovirus?

A

A virus with Enzyme Reverse Transcriptase

27
Q

What does enzyme reverse transcriptase do?

A

Typically during transcription DNA is copied to RNA, this enzyme reverses this process and converts RNA to single stranded DNA.
SS DNA is recopied using the enzyme to become DS DNA and becomes a parasite

28
Q

What is the viral double stranded DNA called?

(That is inserted into the huam DNA)

A

Provirus stage of infection

29
Q

What is a provirus capable of producing?

A

New viral particles

(Virions)

30
Q

What is the name of the provirus stage when it is in hiding?

A

Latent stage
-When it emerges the cycle continues

31
Q

What is the end stage of HIV?

A

AIDS

32
Q

What is Kaposi’s sarcoma?

A

Cancerous tumours caused by T-helper cells turned into cancer cells by HIV/AIDS

33
Q

What are the stages of AIDS created by CDC?

A

Stage A
Stage B
Stage C

34
Q

What is Stage A?

A

-T-helper cell count falls to 500/mm3
-leads to Lymphademopathy (swollen lymph nodes)

35
Q

What is the normal T helper cell count in a healthy person?

A

1500-3000/mm3
-1000 or higher

36
Q

What is Stage B?

A

T-helper cell count is 200-499/mm3

37
Q

What is Stage C?

A

Less than 200 t-helper cells

38
Q

What does Stage C signify?

A

Clinical AIDS

39
Q

How is AIDS transmitted?

A

mostly Blood and semen
also vaginal secretions, breast milk and Saliva

40
Q

How many AIDS virions are transmitted through blood?

A

1000-10000 virions IP/mm3

41
Q

How many AIDS virions are transmitted through semen?

A

10-1000 virions IP/mL

42
Q

How many AIDS virions are transmitted through saliva?

A

1 IP/mL
-Very rare source

43
Q

What therapy treats AIDS?

A

Highly Anti Retroviral Therapy

44
Q

What are examples of Antiretroviral drugs (NRTI’s) used to treat AIDS?

A
  1. Zidovudine® (AZT)
  2. Lamivudine ® (3-TC)
45
Q

Why is it difficult to develop a vaccine for AIDS/HIV?

A

It is highly mutated and most patients have multiple strains when infected

46
Q

What are Cytopathic effects?

A

Consequences of viral infections

47
Q

What are 4 main types of Cytopathic effects?

A
  1. Lytic/Acute infection
  2. Persistent infection
  3. Latent infection
  4. Cancer
48
Q

What is a Lytic/Acute infection?

A

Causes lysis of cells
e.g Cold virus, Influenza

49
Q

What is a persistent infection?

A

Infection for months-years until death
-No virus cell death, it remains in host
e.g, Measles, SSPE (neurological degeneration –> death)

50
Q

What is a Latent infection?

A

Virus hides in cells and then emerges
- happens over years or months
e.g Herpes-1 aka Cold sores
Herpes-3 aka Shingles
Herpes-4 aka Mono

51
Q

Example of a virus turning a host cell to cancer?

A

EB virus (Herpes-4) converts cells in jaw into a tumour called Burkitt’s lymphoma
-Targets B cells
-Leads to nasopharyngeal cancer