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Pharmacology 200 > 3 - antivirals > Flashcards

3 - antivirals Flashcards

1
Q

what are viruses

A

obligate intracellular parasites

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2
Q

what does it mean to be an obligate intracellular parasite

A

they rely on host biosynthetic machinery to reproduce

they dont make their own proteins

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3
Q

what is a virion

A

when viruses are not inside a cell, they are independent particles

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4
Q

what do virions consist of

A 
double or single stranded DNA
protein coat
lipid envelope(derived from host cell)
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5
Q

what is a capsid

A

protein coat to keep genetic material inside

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6
Q

what are the antigenic glycoproteins

A

important to determine which cells the viruses will affect

in the lipid envelope

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7
Q

what is viral range

A

the group of cell types that a virus can infect

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8
Q

what is a bacteriophage

A

virus that only infects bacteria

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9
Q

what are animal and plant viruses

A

viruses that infect animals and plants

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10
Q

why are animal viruses able to cross phyla

A

they cant, they often only infect closely related species (humans and primates)

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11
Q

what are the three shapes of viruses

A

helical
icosahedral
complex (bacteriophages)

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12
Q

what is pathogenicity

A

ability of virus to cause disease and replicate within host

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13
Q

what is virulence

A

degree of virulence (how sick host gets)

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14
Q

what is latency

A

the concept that some viruses can remain dormant in organisms for a long time
(ex: chicken pox)

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15
Q

what are carriers

A

people that chronically infected and serve as reservoirs of infectious virus

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16
Q

where does the chicken pox virus stay in the body

A

dorsal root ganglia

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17
Q

what are the 4 steps of lytic cycle of viral replication

A

absorption(into host cell), penetration(of genetic material into cytoplasm or host cell), replication(make DBA or RNA), release (virions released into environment)

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18
Q

what determines the host range of a virus and begins the infection process

A

the surface of viruses (proteins that bind to receptors proteins on host cell)

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19
Q

what are the classifications of viruses (not structure)

A

RNA, DNA, single stranded, double stranded

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20
Q

do DNA viruses come with their own DNA

A

yes

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21
Q

what happens once DNA viruses enter the host cell

A

their DNA is transcribed into mRNA by host cell polymerase, then translated into proteins

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22
Q

what makes poxviruses so special

A

they carry their own RNA polymerase and replicate in the host cell cytoplasm
but they use host cell to translate

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23
Q

how can RNA viruses replicate

A

either the mRNA can be transcribed from RNA to mRNA (using enzymes in virion)
or the viral RNA itself can act as mRNA

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24
Q

how do RNA viruses get RNA polymerase

A

they make it themselves (they use host machinery to make it from their own RNA)

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25
Q

where do most RNA viruses complete their replication

A

in the host cell cytoplasm

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26
Q

where do influenza viruses complete their replication

A

transcribed in the host cell nucleus

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27
Q

what are special about retroviruses

A

have RNA genome that directs the formation of a DNA molecule

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28
Q

how does RNA go to DNA with retroviruses

A

using reverse transcriptase (RNA dependent DNA polymerase)

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29
Q

what happens to the dsDNA made from retroviruses

A

it is integrated into the chromosomal DNA of host cell

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30
Q

how is retroviral DNA transcribed

A

by host machinery into RNA

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31
Q

how do most retroviruses kill their host cells

A

they dont kill their host cells initially, they infect them and create a lot of infected daughter

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32
Q

what can vaccines consist of

A

live attenuated or killed viruses

or viral proteins

33
Q

where can anti-viral drugs exert actions

A

viral entry
nucleic acid synthesis
protein synthesis and processing
viral packaging and release

34
Q

what does virustatic mean

A

it does not kill the virus, they just impede infection/ stop replication

35
Q

are antivirals virustatic or cidal

A

static

36
Q

what is acyclovir

A

nucleoside analog which viruses use for replication

37
Q

why does acyclovir result in DNA chain termination

A

it lacks OH group which is important for forming the backbone of the DNA molecule

38
Q

what infection is acyclovir used for

A

herpes

39
Q

what is thymidine kinase

A

made by herpes virus that phosphorylates acyclovir

40
Q

what must happen before acyclovir can be incorperated into DNA

A

it must be phosphorylated

41
Q

how is acyclovir phosphorylated

A

by thymidine kinase

42
Q

why does acyclovir mess up human DNA

A

because thymidine kinase has a affinity for acyclovir 200x than that of mammalian enzyme

43
Q

what is the major excretion route of acyclovir

A

renal excretion

44
Q

how can acyclovir be administrated

A

topical, oral, intravaneous, butt

45
Q

what is the oral bioavailability of acyclovir

how does it change with dose

A

10-30% and decreases with increasing dose

46
Q

what is the half life of acyclovir

A

2.5h

47
Q

how does acyclovir resistance happen

A

impaired production of thymidine kinase or altered specificity

48
Q

what does amantadine do (broad)

A

inhibits viral uncoating (early step in replication)

49
Q

what virus does amantadine affect

A

influenza A

50
Q

what does amantidine do (specific)

A

blocks H+ transfer through M2, blocking acidification and initiation of transcription

51
Q

what is the M2 protein

A

a proton ion channel which allows acidification of the virus core (activates viral RNA transcriptase)

52
Q

what does RNA transcriptase require to be activated

A

acidification of the virus core

53
Q

what happens to the viral core at the onset of infection

A

it becomes acidic

54
Q

does amantidine protect against influenza A

A

yes

but there are resistant strains

55
Q

does amantidine protect against influenza B

A

no

56
Q

what is the alternative if someone is not able to get vaccine (immunocompromised)

A

seasonal prophylaxis using anti-virals

57
Q

what is zanamivir

A

anti influenza drug

58
Q

how does zanamivir work

A

inhibits neuroaminidases produced by influenza A and B (works after replication) to impede viral spread

59
Q

what do neuroaminidases do

A

cleave sialic acid residues from viral proteins which enables virus to be released from the host cell

60
Q

what kind of virus is HIV

A

lentivirus (retrovirus)

61
Q

what are special about lentiviruses

A

they lead to chronic persistent infection with gradual onset of clinical symptoms

62
Q

what kind of cells does HIV attack

A

CD4+ T cells

63
Q

what happens to the CD4+ T cells when infected to HIV

A

the levels decline below a critical level, leading to AIDS (lose cell mediated immunity)

64
Q

how does replication change after HIV infection

A

it doesnt, replication is constant

65
Q

what is HAART

A

highly active antiretroviral therapy

target multiple pathways alone the infection route

66
Q

what does maraviroc do

A

CCR5 receptor antagonist

blocks HIV from binding to the CD4 receptor on T cell

67
Q

how does HIV infection begin (what attaches)

A

attachment of HIV envelope proteins (gp120) to CD4 and CCR5 receptors on the surface of T cells

68
Q

what do HIV entry inhibitors intefere with

A

binding fusion and entry into cell

69
Q

how does HIV reverse transcriptase enzymes work

A

synthesize DNA from HIV RNA using nucleosides in the host T-cells (RNA dependent DNA pol)

70
Q

how do nucleoside reverse transcriptase inhibitors work

A

they are incorperated into the HIV DNA but lack 3’OH so it causes chain termination

71
Q

why dont nucleoside reverse transcriptase inhibitors work on human cells

A

mammalian RNA and DNA polymerases are sufficiently distinct to permit a selective inhibition of viral reverse transcriptase rather than host cells

72
Q

what are non nucleoside reverse transriptase inhibitors

A

drugs that block the transcription of viral DNA but they dont compete with nucleoside triphosphates

73
Q

how do non nucleoside reverse transriptase inhibitors work

A

they bind to a different site than NRTIs (they bind to reverse transcriptase) and inhibit the activity of reverse transcriptase

74
Q

what are integrase strand transfer inhibitors

A

blocks the integration of viral DNA into the host gene

75
Q

what is integrase

A

viral enzyme that inserts viral genome into the DNA of the host cell

76
Q

what is raltegravir

A

integrase strand transfer inhibitors

77
Q

what are protease inhibitors

A

at latest stage of viral transcription process, blocks final maturation and release of HIV virion into the enviro
blocks aspartate proteases so that virion particles never reach their mature form

78
Q

what is aspartate protease

A

a viral enzyme that cleaves precursor proteins to form the final structure proteins of the mature virion core

Pharmacology 200 (29 decks)

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