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Molecules to Cells - Genetics and Virology > Lecture 34. Virus Replication Cycle 1 > Flashcards

Lecture 34. Virus Replication Cycle 1 Flashcards

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1
Q

What is the cytopathic effect ?

A

Cell to cell spread of virus resulting in plaque formation

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2
Q

How can the cytopathic effect be useful to scientists ?

A

A way to count viruses - plaque assay

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3
Q

What is the assumption of counting the cytopathic effect ?

A

Each plaque begins with 1 virus particle

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4
Q

How does the cytopathic effect contribute to HIV ?

A
  1. Infects CD4+ T-cells

2. Constant destruction of T-cells

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5
Q

How does the cytopathic effect contribute to poliovirus ?

A
  1. Leads to gut and central nervous system infection

2. Muscle weakness

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6
Q

What is a susceptible cell ?

A

A cell which has a functional receptor for a given virus, allowing the virus to enter the cell (the cell may or may not be able to support virus replication)

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7
Q

What is a resistant cell ?

A

Has no receptor (the cell may or may not be able to support virus replication)

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8
Q

What is a permissive cell ?

A

Has the capacity to support virus replication (may or may not be susceptible)

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9
Q

Where can a virus enter and replicate ?

A

In a cell that is both susceptible and permissive

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10
Q

What are initial collisions between virions and cells governed by ?

A

Chance

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11
Q

Do virions have powers of locomotion ?

A

No, they are inanimate

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12
Q

How is virus movement driven ?

A

Brownian motion, diffusion, electrostatic interactions

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13
Q

What are the two steps of attachment ?

A
  1. Adherence to cell surface

2. Attachment to specific receptor molecules on the cell surface

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14
Q

How do virions attach to the cell surface ?

A
  1. Electrostatic interactions

2. Non-specific interactions

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15
Q

What type of interactions occur between virions and receptors on cell surface ?

A

Specific and specialised

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16
Q

How many receptors can be involved in virions attaching to receptors on cell surface ?

A

More than one

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17
Q

Can different virus bind to the same receptor ?

A

Yes

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18
Q

Can virus bind to more than one type of receptor ?

A

Yes

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19
Q

What is the poliovirus receptor ?

A

CD155

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20
Q

What is CD155 ?

A

Cellular adhesion protein

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21
Q

What superfamily is CD155 from ?

A

Immunoglobulin

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22
Q

Where is CD155 expressed ?

A
  1. Endothelial cells

2. Immune cells

23
Q

How does CD155 interact with poliovirus ?

A

By the viral capsid

24
Q

What is the influenza virus receptor ?

A

Sialic acid

25
Q

What is sialic acid ?

A

Small sugar modification attached to the many different proteins on the cell surface

26
Q

Where is sialic acid expressed ?

A

Respiratory endothelium

27
Q

How does sialic acid interact with the influenza virus ?

A

Viral Hemagglutinin Protein (Ha)

28
Q

What is the HIV receptor ?

A

CD4

29
Q

What is the HIV receptor superfamily ?

A

Immunoglobulin

30
Q

What is CD4’s co-receptor ?

A

CCR5 or CXCR4

31
Q

Where is CD4 expressed ?

A

CD4 positive T-cells

32
Q

Where doe the HIV virus interact with the virus ?

A

Viral gp120 and gp41 proteins

33
Q

What is varicella zoster virus receptor ?

A

Heparin sulfate proteoglycans

34
Q

What is varicella zoster virus cellular tropism ?

A
  1. Mucosal epithelia - upper respiratory tract
  2. Lymphoid tissue
  3. Skin
  4. Latent infection - ganglionic neurons
35
Q

Where does varicella zoster virus receptor interact with virus ?

A

Viral gB protein

36
Q

What is SARS-CoV-2 receptor ?

A

Angiotensin converting enzyme (ACE2)

37
Q

Where is the ACE2 receptor expressed ?

A

Broad distribution- epithelial respiratory cells

38
Q

Where does ACE2 receptor interact with the virus ?

A

Viral spike protein

39
Q

What does receptor specificity determine ?

A

Susceptibility of cells

40
Q

How do cells internalise things from outside the cell ?

A
  1. Phagocytosis

2. Endocytosis

41
Q

How does HIV enter the cells ?

A

Fusion at the plasma membrane

42
Q

What are the 4 ways viruses enter cells ?

A
  1. Clathrin dependent endocytosis
  2. Clathrin/caveolin independent endocytosis
  3. Caveolin dependent endocytosis
  4. Fusion at the plasma membrane
43
Q

What is the HIV entry to the cell process?

A

A pH independent process

44
Q

What does interaction between viral proteins and cellular receptors trigger in HIV ?

A

Conformational change in viral proteins

45
Q

What are the two conformational changes in viral proteins in HIV ?

A
  1. Change in gp120 promotes binding to chemokine receptor

2. Change in gp41 exposes fusion peptide, which inserts into T-cell membrane

46
Q

What does the conformation change mediate ?

A

Membrane fusion

47
Q

How does influenza enter the cells ?

A

Low pH dependent receptor mediated endocytosis

48
Q

What triggers conformational change in Hemagglutinin (HA) viral protein in influenza entry ?

A

Acidification of endosomes

49
Q

How do non-enveloped viruses (poliovirsu) enter cells

A

Receptor dependent conformational change of virion creates a pore in endosomal membrane

50
Q

What forms the pore in the endosomal membrane in poliovirus ?

A

VP1

51
Q

What is the model of genome uncoating ?

A
  1. Virion binds to receptor
  2. Conformational change - VP1 inserted into plasma membrane
  3. A pore is formed in the membrane by VP1, the RNA genome is released into cytosol
52
Q

How does SARS-CoV-2 enter the cell ?

A

Receptor mediated endocytosis

53
Q

What cuts the viral spike protein in SARS-CoV-2 in specific places ?

A

TMPRSS2

54
Q

What does the conformational change in the spike protein in SARS-CoV-2 result in ?

A

The spike protein becoming embedded in the endosomal vesicle membrane

Molecules to Cells - Genetics and Virology (16 decks)

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