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Biology 416 VIROLOGY > Attachment & Entry > Flashcards

Attachment & Entry Flashcards

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1
Q

What is the criteria to identify receptors for viruses?

A

Loss of function
- disruption of receptor gene blocks infection

Gain of function
- Receptor gene confers susceptible

Antibody specific to receptor blocks infection

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2
Q

What is essential for coronavirus (MERS) infection?

A

Dipeptidyl peptidase 4 (DPP4)

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3
Q

Where is DPP4 expressed?

A

Lung and kidney cells

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4
Q

What are types of cleavage enzymes?

A

Growth factors, chemokines, neuropeptides, vasoactive peptides

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5
Q

What is an “Natural” Plasmid?

A

Origin of Replication

Advantageous gene

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6
Q

What is a “Artificial” Plasmid?

A

Origin of replication

Selectable marker

Cloning site
- insert gene of interest (GOI)

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7
Q

Which plasmid is usually used for scientists?

A

“Artificial” plasmids

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8
Q

What is a plasmid?

A

Small circular piece of DNA that replicates independently from the host’s chromosomal DNA

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9
Q

Where are plasmids mainly found?

A

Bacteria

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10
Q

What are plasmids also known as?

A

Vector

Construct (artificial plasmids)

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11
Q

How do non-enveloped viruses interact with receptors?

A

Bind via projections

Protein-protein interaction

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12
Q

How do enveloped viruses (HIV) interact with receptors?

A

Bind via transmembrane glycoproteins

protein-protein interaction (because both are proteins)

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13
Q

How do enveloped viruses (Influenza) interact with receptors?

A

Bind via transmembrane glycoproteins

protein-carbohydrate interaction

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14
Q

What is the reasoning for the name glycoproteins?

A

Lots of sugar and molecules in them

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15
Q

What makes the influenza virus different from HIV?

A

the interaction

  • protein-protein (HIV)
  • protein-carbohydrate (Flu)

Influenza has a HA (hemagglutinin) trimer and NA (neuraminidase) tetramer

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16
Q

What recognizes the bondage of the terminal sialic acid and galactose in the host cell?

A

Viral envelope protein HA (hemagglutinin)

17
Q

What type of linkages bond the terminal sialic acid and galactose?

A

a(2,6) linkages for humans

a(2,4) linkages for birds

both linkages present in pigs

18
Q

Why does HA binding affinity and NA activity need to be balanced?

A

For efficient viral entry and release

19
Q

What happens if HA binding affinity > NA activity?

A

Trapped binding

- blocked/inefficient entry/release

20
Q

What happens if NA activity > HA binding affinity?

A

Inefficient receptor binding

21
Q

How does HIV-1 enter the cell?

A

Fusion at the plasma membrane

22
Q

How is fusion regulated in HIV?

A

conformational changes

binding to receptor

23
Q

What is CD4?

A

HIV host receptor

24
Q

What is CCR5/CXCR4?

A

HIV coreceptor

25
Q

What is gp120 (trimer)?

A

Viral surface protein in HIV that interacts with CD4

26
Q

What is gp41 (trimer)?

A

Viral transmembrane protein in HIV that mediates fusion

27
Q

How does SARS-CoV-2 enter the cell?

A

Fusion at the plasma membrane

28
Q

How is fusion regulated in SARS-CoV-2?

A

Conformational changes

Cleavage of viral glycoprotein

By host protein

29
Q

How does dengue enter the cell?

A

Acid-catalyzed (Dengue)

Enter by endocytosis
- Clathrin-dependent endocytosis

30
Q

How is fusion regulated in Dengue?

A

low pH

- conformational changes expose fusion peptide

31
Q

How does Ebola enter the cell?

A

Membrane fusion
- Endosomal fusion receptor

Clathrin-dependent endocytosis

32
Q

How is fusion regulated in Ebola?

A

Low pH
- GP cleavage

GP binds to fusion receptor
- Niemann-Pick C1 protein
- Niemann-Pick type C1 disease
        - Patient cells resistant to Ebola virus infection 
          (mutation in cell)
33
Q

How do non-enveloped viruses enter and move within cells?

A

Disruption of endosomal membrane

Forming a pore in the endosomal membrane

34
Q

How does Adenovirus enter cells?

A

Disruption of endosomal membrane

Adenovirus is non-enveloped

Clathrin-dependent endocytosis

35
Q

How is fusion regulated in Adenovirus?

A

Low pH

  • capsid destabilization, release of proteins
  • destabilize endosomal membrane
36
Q

How does Poliovirus enter cells?

A

Forming a pore in the endosomal membrane

Poliovirus is non-enveloped

Clathrin-dependent endocytosis

37
Q

How is fusion regulated in poliovirus?

A

Conformational rearrangements

  • VP1/VP4 = interior to exterior capsid surface
  • Formation of pore
38
Q

What are the big changes between enveloped viruses and non-enveloped viruses?

A

???

Biology 416 VIROLOGY (7 decks)

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