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MODA Questions > Antiviral drugs > Flashcards

Antiviral drugs Flashcards

1
Q

What are the features of the influenza genome?

A
  1. Eight segments
  2. ssRNA
  3. Negative sense
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2
Q

What is the function of the influenza M2 ion channel?

A

Triggers uncoating of genome when virus is exposed to low pH

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3
Q

What surrounds the influenza nucleocapsid?

A

Lipid bilayer envelope

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4
Q

Which two spike proteins are located in influenza envelope?

A
  1. Haemagglutinin

2. Neuraminidase

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5
Q

What is the function of haemagglutinin?

A

Mediates initial attachment of virus to host cell

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6
Q

How is the influenza nucleocapsid released from its envelope?

A

Haemagglutinin undergoes structural rearrangement following attachment, endocytosis and acidification

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7
Q

What is the function of neuraminidase?

A
  1. Prevents viral aggregation
  2. Facilitates release from host cells
  3. Possible role as virulence factor
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8
Q

What is responsible for antigenic drift and shift in influenza?

A

Variations and mutations in neuraminidase and haemagglutinin

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9
Q

What do anti-herpes agents target?

A

Virally-encoded DNA polymerases

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10
Q

How do viral DNA polymerases act?

A

In the same manner as eukaryotic DNA polymerases

Join 5’-OH of base being added to 3’-OH of sugar in polymerised strand of DNA

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11
Q

What is the distinguishing feature of purine analogues?

A

All lack cyclic sugar of 2’-deoxyguanosine

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12
Q

Why is aciclovir selective for virus-infected cells?

A
  1. Only virus-infected cells have thymidine kinase required to monophosphorylate drug
  2. Drug preferentially binds to viral DNA polymerase
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13
Q

Why do ganciclovir and penciclovir permit chain extension?

A

They have 3’OH moieties

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14
Q

What is contained in an HIV virion?

A
  1. Two copies of ssRNA genome
  2. Reverse transcriptase
  3. Aspartic protease
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15
Q

What is the role of HIV reverse transcriptase?

A

Converts ssRNA to dsDNA

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16
Q

How is HIV DNA integrated into the human genome?

A

Integrase enzyme

17
Q

What are the properties of the HIV reverse transcriptase?

A
  1. Poor fidelity
  2. Many frequent transcription errors
  3. High degree of sequence variation among viral genome copies that are produced
18
Q

What is the role of the HIV aspartic protease?

A

Cleaves polyprotein allowing maturation of HIV proteins and capsid formation

19
Q

How do non-nucleoside reverse transcriptase inhibitors work?

A

Bind to enzyme near catalytic site and denature it

20
Q

How do nucleoside reverse transcriptase inhibitors work?

A

Bind to target enzyme by mimicking naturally occurring nucleosides and terminate DNA chains once they are incorporated because they lack a 3’OH moiety

21
Q

How are nucleoside reverse transcriptase inhibitors activated?

A

Phosphorylated by host cell enzymes

22
Q

What is often co-administered with pyrimidine analogues?

A

Hydroxyurea

23
Q

What is the role of hydroxyurea?

A

Inhibit ribonucleotide reductase

24
Q

What is the effect of inhibiting ribonucleotide reductase?

A

Decreases intracellular pool of pyrimidine nucleotides

25
Q

What is the mRNA transcribed from the HIV provirus translated to?

A

Gag proteins

26
Q

What are gag proteins?

A

Biochemically inert polypeptides

27
Q

How are gag polypeptides converted to functional proteins?

A

Cleaved by HIV protease at the appropriate positions as virus is budding from the cell membrane or shortly after

28
Q

What does HIV protease have in its active site?

A

Two aspartyl residues

29
Q

What are interferons?

A

Potent immunoregulatory cytokines synthesised in response to viral infection, causing biochemical changes that inhibit viral propagation

30
Q

Which interferons have antiviral activity?

A

IFN-α and IFN-β

31
Q

Which interferon has antitumour activity?

A

IFN-α

32
Q

How do interferons work?

A
  1. Bind to specific ganglioside receptors on host cell membranes
  2. Promote production of enzymes that inhibit transcription of viral mRNA in host cell ribosomes
33
Q

What is IFN-α-2a used to treat?

A
  1. Hepatitis B infections

2. AIDS related Kaposi’s sarcoma

34
Q

What is IFN-α-2b used to treat?

A

Hepatitis C

MODA Questions (7 decks)

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