Attachment & Entry

Question 1

What is the criteria to identify receptors for viruses?

Answer 1

Loss of function
- disruption of receptor gene blocks infection

Gain of function
- Receptor gene confers susceptible

Antibody specific to receptor blocks infection

Question 2

What is essential for coronavirus (MERS) infection?

Answer 2

Dipeptidyl peptidase 4 (DPP4)

Question 3

Where is DPP4 expressed?

Answer 3

Lung and kidney cells

Question 4

What are types of cleavage enzymes?

Answer 4

Growth factors, chemokines, neuropeptides, vasoactive peptides

Question 5

What is an “Natural” Plasmid?

Answer 5

Origin of Replication

Advantageous gene

Question 6

What is a “Artificial” Plasmid?

Answer 6

Origin of replication

Selectable marker

Cloning site
- insert gene of interest (GOI)

Question 7

Which plasmid is usually used for scientists?

Answer 7

“Artificial” plasmids

Question 8

What is a plasmid?

Answer 8

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

Question 9

Where are plasmids mainly found?

Answer 9

Bacteria

Question 10

What are plasmids also known as?

Answer 10

Vector

Construct (artificial plasmids)

Question 11

How do non-enveloped viruses interact with receptors?

Answer 11

Bind via projections

Protein-protein interaction

Question 12

How do enveloped viruses (HIV) interact with receptors?

Answer 12

Bind via transmembrane glycoproteins

protein-protein interaction (because both are proteins)

Question 13

How do enveloped viruses (Influenza) interact with receptors?

Answer 13

Bind via transmembrane glycoproteins

protein-carbohydrate interaction

Question 14

What is the reasoning for the name glycoproteins?

Answer 14

Lots of sugar and molecules in them

Question 15

What makes the influenza virus different from HIV?

Answer 15

the interaction

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

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

Question 16

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

Answer 16

Viral envelope protein HA (hemagglutinin)

Question 17

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

Answer 17

a(2,6) linkages for humans

a(2,4) linkages for birds

both linkages present in pigs

Question 18

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

Answer 18

For efficient viral entry and release

Question 19

What happens if HA binding affinity > NA activity?

Answer 19

Trapped binding

- blocked/inefficient entry/release

Question 20

What happens if NA activity > HA binding affinity?

Answer 20

Inefficient receptor binding

Question 21

How does HIV-1 enter the cell?

Answer 21

Fusion at the plasma membrane

Question 22

How is fusion regulated in HIV?

Answer 22

conformational changes

binding to receptor

Question 23

What is CD4?

Answer 23

HIV host receptor

Question 24

What is CCR5/CXCR4?

Answer 24

HIV coreceptor

Question 25

What is gp120 (trimer)?

Answer 25

Viral surface protein in HIV that interacts with CD4

Question 26

What is gp41 (trimer)?

Answer 26

Viral transmembrane protein in HIV that mediates fusion

Question 27

How does SARS-CoV-2 enter the cell?

Answer 27

Fusion at the plasma membrane

Question 28

How is fusion regulated in SARS-CoV-2?

Answer 28

Conformational changes Cleavage of viral glycoprotein By host protein

Question 29

How does dengue enter the cell?

Answer 29

Acid-catalyzed (Dengue) Enter by endocytosis - Clathrin-dependent endocytosis

Question 30

How is fusion regulated in Dengue?

Answer 30

low pH | - conformational changes expose fusion peptide

Question 31

How does Ebola enter the cell?

Answer 31

Membrane fusion - Endosomal fusion receptor Clathrin-dependent endocytosis

Question 32

How is fusion regulated in Ebola?

Answer 32

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) ```

Question 33

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

Answer 33

Disruption of endosomal membrane Forming a pore in the endosomal membrane

Question 34

How does Adenovirus enter cells?

Answer 34

Disruption of endosomal membrane Adenovirus is non-enveloped Clathrin-dependent endocytosis

Question 35

How is fusion regulated in Adenovirus?

Answer 35

Low pH - capsid destabilization, release of proteins - destabilize endosomal membrane

Question 36

How does Poliovirus enter cells?

Answer 36

Forming a pore in the endosomal membrane Poliovirus is non-enveloped Clathrin-dependent endocytosis

Question 37

How is fusion regulated in poliovirus?

Answer 37

Conformational rearrangements - VP1/VP4 = interior to exterior capsid surface - Formation of pore

Question 38

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

Answer 38

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