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PHA4107 > Antiviral drugs > Flashcards

Antiviral drugs Flashcards

1
Q

What is a virus?

A

An infectious, obligate intracellular molecule comprising of genetic material (DNA or RNA) surrounded by a protein coat and sometimes a membrane

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2
Q

Virus infectious cycle (n=5 steps)

A
  1. Attachment and entry
  2. Production of viral mRNA and protein synthesis
  3. Genome replication
  4. Assembly and release of viral particles
  5. Maturation
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3
Q

Productive infection requires ___________ and _________: these are all potential antiviral targets

A

Viral and host proteins

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4
Q

All viral genomes must be copied to produce _________ that can be read by host ribosomes

A

mRNA

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5
Q

Baltimore system of classification (n=7)

A 
I.   dsDNA
II.   ssDNA
III.  dsRNA
IV. + ssRNA
V.  - ssRNA
VI. + ssRNA with dsDNA intermediate
VII. Gapped dsDNA
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6
Q

Challenges of antiviral development:

Safety: described in terms of ________ index (for cells) and ___________ index (for host)

Potency: even modest reproduction in presence of ____________ provides the opportunity for appearance of ____________ mutants

A

Cytotoxic; therapeutic

Inhibitors; resistant mutants

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7
Q

Drugs for Herpesvirus infection (n=2)

A
  • Nucleoside and nucleotide analogues (Ribvarin, Acyclovir, AZT)
  • Foscarnet
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8
Q

Nucleoside and nucleotide analogues
- Ribvarin: synthetic ______________ analogue. Active against multiple ________ and ________ viruses in vitro. Approved for treatment of ____________ and _______

  • Acyclovir: specific ____________ drug. Effective against ____________ virus. Nucleoside analogue related to ______________ and contains _____________ groups.
  • AZT: first drug licensed for treatment of ______ infection. An analogue of _______________.
A
  • Guanosine; DNA and RNA; RSV and HCV
  • Non-toxic; Herpes simplex; guanosine; acyclic
  • HIV; thymidine
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9
Q

Nucleoside drugs activation and mechanism of action:

  • Conversion to the ____________ form requires sequential activities of _________ and/or ________ kinases to produce a triphosphate derivative.
  • Requirement for viral _________ for activation of the drug provides _____________ to infected cells
  • Most agents work by mediating _______________ of DNA synthesis
A
  • Active; viral and/or host
  • Kinases; specificity
  • Chain termination
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10
Q

Acyclovir and Valacyclovir

  • Treatment for __________ and __________
  • Not sufficiently active against ________
  • Valacylovir is a ______________ with enhanced oral _________________ and is converted to acyclovir by ____________ and _____________ enzymes
A
  • HSV and VZV
  • CMV
  • Prodrug; bioavailability; intestinal and hepatic
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11
Q

Herpesvirus resistance to Acyclovir and other nucleoside analogue drugs

Cause of resistance: loss of thymidine _________ or any other _________ protein(s)

A
  • Kinase; viral
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12
Q

Foscarnet

  • The only non _________ /____________ antiviral against _____________ infection
  • Noncompetitive _________ that binds directly to pyrophosphate binding site of catalytic centre of Herpesvirus ________ polymerase
  • Doesn’t require activation by _________ or _______ proteins
  • Active against: _______ , _________, __________
  • Mostly used to treat ________ in patients w/ AIDS, ______________ HSV infections and ____________
A
  • Nucleoside/nucleotide; herpesvirus
  • Inhibitor; DNA
  • Viral or host
  • HSV, VZV, CMV
  • CMV; acyclovir-resistant; shingles
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13
Q

Drugs for HIV infection:

  • Inhibitors of viral protease:
  • Inhibitors of strand transfer:
  • Entry inhibitors:
A
  • Squinavir and Darunavir
  • Raltegravir and Dolutegravir
  • Maraviroc and Enfuvirtide
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14
Q

Saquinavir and Darunavir

  • Inhibitory peptide __________-
  • Darunavir is a second generation ____________________ for which many mutations in the virus are required to develop ___________
A
  • Mimic

- Peptidase inhibitor; resistance

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15
Q

Raltegravir and Dolutegravir

- Prevents DNA strand ___________ (integration) by binding divalent cations in catalytic core of _________

A
  • Transfer; integrase
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16
Q

Maraviroc and Enfuvirtide

  • _____________ inhibitors
  • Mechanism:
    1. Virus enters via fusion ________
    2. Maraviroc binds to ____________
    3. Doesn’t bind to viral glycoproteins but targets host proteins
    4. Maraviroc is only active against ______________ HIV
A
  • Entry
  1. Proteins
  2. Co-receptor
  3. CCR5-tropic
17
Q

Mutations in DNA and RNA viruses

RNA viruses:

  • Lack of _______________ activity in RdRP
  • Average error frequency: in a 10 kb genome, ___ mutation per genome

DNA viruses:

  • ______________ activity
  • Don’t make as many ___________ as RNA viruses
  • Most DNA viruses generate less __________ and evolve ____________ than RNA viruses
A
  • Proofreading
  • 1
  • Proofreading
  • Mistakes/mutations
  • Diversity; slower
18
Q

Combination therapy

Highly active antiretroviral therapy (HAART): multi drug treatment which ___________ viral loads and improves ____________ in HIV-positive individuals

  • Combining ___ or more drugs w/ distinct target __________ chance of ___________ virus : genome must carry multiple ___________ to confer resistance
  • Mutations appear only when viral genome is ___________. If replication is blocked by an inhibitor, no new drug resistant mutants can __________
A
  • Reduces; survival
  • 2; reduces; resistant; mutations
  • Replicated; arise
19
Q

Drugs for Hepatitis C virus (HCV)

A
  • Direct-acting antiviral drugs (DAAs)
  • HCV RNA polymerase inhibitor (Sofosbuvir)
  • Sofosbuvir can effectively treat genotype 1 to 4 of HCV
  • Velpatasvir can effectively treat all 6 genotypes of HCV
20
Q

HCV infectious cycle and antiviral drugs:

  • Due to high ______________ rate of HCV RNA polymerase, the use of _______________ therapy is required
  • Combined use of DAAs cures about _____ of patients
A
  • Mutation; combination

- >90%

21
Q

Drugs for influenza

A
  • Amantadine

- Zanamivir and Oseltamivir: neuraminidase inhibitors

22
Q

Amantadine:

  • Targets influenza A virus _____ protein which forms tetramer that creates ___________________ ion channel that transports protons
  • Amantadine binding to outside of tetramer is thought to ___________ entry of __________ allosterically
  • Emergence of resistance strain has rendered Amantadine highly _________________
A
  • M2; transmembrane
  • Block; protons
  • Ineffective
23
Q

Zanamivir and Oseltamivir

  • Block ______________________ which is important for virus _____________ from host cell
  • Highly _____________ so given as a last resort
A
  • Neuraminidase; release

- Toxic

24
Q

Biologics

A
  • Palivizumab

- Interferons

25
Q

Palivizumab

  • Prevents and treats _____
  • Humanized monoclonal __________ that inactivates _________ proteins of RSV
A
  • RSV

- Antibody; fusion

26
Q

Interferons and pegylated interferons

  • Group of glycoprotein _____________ normally secreted during __________ to induce antiviral state
  • For therapeutic use, they’re produce by recombinant ______ technology
  • Pegylated derivatives are now available: have increased _________ and administered _____ a week instead of 3 times a week for non-pegylated form
A
  • Cytokines; infection
  • DNA
  • Half-life; once

PHA4107 (4 decks)

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