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PMCOL 200 Final > Antiviral Medication > Flashcards

Antiviral Medication Flashcards

1
Q

What are obligate intracellular parasites? Provide an example.

A
  • rely on host biosynthetic machinery to reproduce

- virus

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2
Q

Are viruses alive? If not, explain why.

A

viruses are alive and not alive because they cannot reproduce independently

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3
Q

When not inside an infected cell, what are viruses called?

A

virions

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4
Q

select all that apply…virions consist of:

a) dsDNA
b) ssDNA
c) dsRNA
d) ssRNA

A

virions consist of all 4 options (dsDNA, ssDNA, dsRNA, ssRNA)

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5
Q

In a virion, what is a capsid?

A

a protein coat

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6
Q

In virions, what is a LIFE capsid?

A

lipid envelope derived from the host cell; may contain antigenic glycoproteins

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7
Q

How many proteins do the SIMPLEST viruses encode? How many do most viruses encode? How many do humans encode?

A

simplest –> 4 proteins
most –> 100-200 proteins
humans –> 20,000 proteins

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8
Q

Define viral range.

A

viral range = group of cell types (or species) that a virus can infect

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9
Q

What is a bacteriophage?

A

bacteriophage = a virus that only infects bacteria

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10
Q

What is an animal virus?

A

animal virus = a virus that only infects animals

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11
Q

TRUE or FALSE: most animal viruses are not specific to one species

A

FALSE - most animal viruses cannot cross phyla, and some can only infect closely related species

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12
Q

What is plant virus?

A

plant virus = a virus that only infects plants

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13
Q

What are the 3 virus shapes?

A

1) helical
2) icosahedral
3) complex

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14
Q

What is pathogenicity?

A

pathogenicity = the ABILITY of a virus to cause diseases

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15
Q

What is virulence?

A

virulence = the DEGREE of pathogenicity

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16
Q

what does latency mean, in terms of viral infection?

A

some viruses can remain dormant in organisms and then be triggered at a later time

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17
Q

Define the term “carriers”.

A

carriers = people who are chronically infected, and serve as reservoirs of infectious virus

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18
Q

What are the 4 steps of the viral replication cycle? Summarize each step in one word.

A

1) Absorption
2) Penetration
3) Replication
4) Release

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19
Q

What occurs during “absorption” in the viral replication cycle?

A
  • the surface of the virus has proteins which bind to the receptors on the host cell
  • this interaction determines VIRAL RANGE
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20
Q

What occurs during “penetration” in the viral replication cycle?

A

viral DNA/RNA crosses plasma membrane to cytoplasm or nucleus

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21
Q

What occurs during “replication” of the viral replication cycle?

A

viral DNA/RNA interacts with host transcription and translation

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22
Q

What occurs during “release” in the viral replication cycle?

A

newly synthesized virion particles are released to continue infection cycle

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23
Q

Which step of the viral replication cycle determines viral range in the host cell?

a) replication
b) absorption
c) penetration
d) release

A

b) absorption

24
Q

Most DNA viruses enter the host cell:

a) nucleus
b) cytoplasm

A

a) nucleus

25
Q

Most RNA viruses enter the host cell:

a) nucleus
b) cytoplasm

A

b) cytoplasm

26
Q

TRUE or FALSE: Retroviruses have DNA genome.

A

FALSE - retroviruses have RNA genome

27
Q

Explain the steps that occur during a DNA virus infection.

A

1) DNA virus enters host cell nucleus
2) viral DNA integrated into host DNA
3) this integrated DNA is transcribed into mRNA by HOST DNA-dependent RNA polymerase
4) the mRNA is translated into viral proteins
5) viral genome is replicated by DNA-dependent DNA polymerase (from host or virus)

(DNA –> mRNA –> protein)

28
Q

Explain the steps that occur during a RNA virus infection.

A

1) dsRNA virus enters cytoplasm of the host cell
2) RNA-DEPENDENT RNA POLYMERASE (made by the virus) acts as a TRANSCRIPTASE (to transcribe/make mRNA)
3) RNA-DEPENDENT RNA POLYMERASE acts as a REPLICASE (to replicate the dsRNA viral genome)
4) translation of the mRNA makes viral proteins

(dsRNA –> dsRNA + mRNA –> protein from mRNA)

29
Q

What is a retrovirus?

A

a virus that has RNA genome that directs formation of DNA

30
Q

Explain the steps that occur during a retrovirus infection.

A

1) viral REVERSE TRANSCRIPTASE (RNA-dependent DNA polymerase) copies viral RNA into viral DNA
2) viral DNA is integrated into host DNA
3) host DNA is transcribed into mRNA
4) mRNA is transcribed into viral protein

(RNA –> DNA –> mRNA –> protein)

31
Q

What 4 forms can vaccinations come in?

A

1) live-attenuated
2) killed virus (inactivated)
3) viral proteins
4) mRNA (antigens)

32
Q

What are 2 forms of virus prevention/therapy?

A

1) vaccination

2) anti-virals

33
Q

Anti-virals are virustatic. What does virustatic mean?

A

virustatic = only effective against replicating viruses (i.e. do not affect latent viruses)

34
Q

What can combination therapy achieve that most other therapies cannot?

A

prevent/delay emergence of RESISTANCE to the anti-viral treatment

35
Q

What antiviral is used to treat herpes simplex?

36
Q

Describe the mechanism that acyclovir uses to fight the herpes simplex virus. (hint: consider the structure of acyclovir) Which stage of the viral replication cycle is this drug involved in?

A
  • acyclovir is a nucleoside analog which viruses incorporate into their genomes during replication (i.e. fake DNA binding block)
  • acyclovir has no OH (OH is necessary to form the DNA backbone) –> DNA CHAIN TERMINATION

stage: replication
(i. e. acyclovir deactivates newly synthesized viral DNA)

37
Q

which base does acyclovir use?

a) adenosine
b) thymine
c) guanine
d) cytosine
e) uracil

A

c) guanine

38
Q

If both the virus and host use guanine in DNA replication, why doesn’t acyclovir deactivate the host DNA? (hint: which enzyme is involved?)

A
  • acyclovir must be phosphorylated by herpes THYMIDINE KINASE to be incorporated into viral DNA
39
Q

TRUE or FALSE: thymidine kinase is MORE efficient than the mammalian equivalent enzyme

40
Q

What are 3 ways in which herpes simplex can develop resistance to acyclovir?

A

1) impaired production of viral thymidine kinase
2) altered thymidine kinase substrate specificity (i.e. only phosphorylate thymine and not acyclovir)
3) altered viral DNA polymerase

41
Q

herpes simplex virus is a:

a) DNA virus
b) RNA virus
c) lentivirus

A

a) DNA virus

42
Q

What does HIV stand for?

A

human immunodeficiency virus

43
Q

HIV is a:

a) DNA virus
b) RNA virus
c) lentivirus

A

c) lentivirus (more specifically, a retrovirus)

44
Q

Explain the infection mechanism of HIV.

A

in general:

1) infect human immune cells (CD4+ T cells)
2) cell-mediated immunity lost
3) replication is constant after the infection

step 1 in detail:
HIV envelope proteins called gp120 attach to CD4 and CCR5 receptors on T cell surface

45
Q

What does HAART stand for? Explain it’s relevance. What virus is it used to treat?

A

HAART = highly active antiretroviral therapy

  • use combination of drugs to slow/reverse increases in viral RNA
  • treat retroviruses like HIV
46
Q

Name the 4 TYPES (classified by mechanism) of antivirals that can be used to treat HIV.

A

1) entry inhibitors
2) reverse transcriptase inhibitors
3) integrase strand transfer inhibitors (ISTIs)
4) protease inhibitors

47
Q

What is maraviroc used to treat? What is its mechanism? Which stage of the viral replication cycle is this drug involved in?

A
  • treat HIV
  • CCR5 receptor antagonist (interfere with HIV binding to T cell)
  • stage: absorption????
48
Q

What are NRTIs? What virus do they treat? What is the mechanism? Which stage of the viral replication cycle is this drug involved in?

A
  • small molecule drugs that are similar to host cell nucleosides
  • treat HIV
  • (viral) reverse transcriptase inhibitor –> nucleoside analogue –> lack OH –> CHAIN TERMINATION (i.e. similar to acyclovir mechanism)
  • stage: replication
49
Q

How are NRTIs similar to acyclovir?

A

both use chain termination

50
Q

What is an integrase?

A

integrase = inserts viral DNA into host DNA

51
Q

What is raltegravir? What virus does it treat? What is its mechanism? Which stage of the viral replication cycle is this drug involved in?

A
  • treat HIV
  • integrase strand transfer inhibitor (prevents integrase from allowing HIV proliferation)
  • stage: replication
52
Q

What is an aspartate protease?

A

viral enzyme that cleaves precursor proteins to form mature viral proteins

53
Q

What is the mechanism of a protease inhibitor? What virus can it treat? What other type of antiviral is it used in combination with? Which stage of the viral replication cycle is this drug involved in?

A
  • mechanism: inhibit aspartate proteases (which make mature viral protein)
  • virus: HIV
  • used in combination with reverse transcriptase inhibitors
  • stage: replication
54
Q

What is amantadine (i.e. what is the mechanism)? What is it used to treat? Which stage of the viral replication cycle is this drug involved in?

A

type of drug: anti-influenza A drug

mechanism in general: inhibit viral uncoating of influenza A virus

mechanism in detail:

  • M2 proton ion channel required for acidification of virus core to activate viral RNA transcriptase
  • amantadine blocks the channel

stage: replication????

55
Q

TRUE or FALSE: Amantadine is prophylactic (preventative) against both influenza A and B.

A

FALSE - amantadine is only prophylactic against influenza A

56
Q

What is zanamavir (i.e. what is its mechanism)? What virus does it treat? Which stage of the viral replication cycle is this drug involved in?

A

type of drug: anti-influenza A and B drug

mechanism in general: impede viral spread

mechanism in detail:

  • neuraminidase cleaves sialic acid from viral proteins, which enables virus to be released from host cell
  • zanamavir is an inhibitor of neuraminidase which is produced by both influenza A and B

stage: release

PMCOL 200 Final (11 decks)

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