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MCD Tutorials > acyclovir > Flashcards

acyclovir Flashcards

1
Q

what does acyclovir treat

A

herpes

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2
Q

effectiveness of acyclovir for herpes

A

reduction in relapse from 44% to 2%

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3
Q

virus features

A

no functional ribososmes or organelles
some genetic material RNA instead of DNA
may be double/single stranded
large variation in genomes
smaller than bacteria
obligate intracellular agents
hijack metabolic process of host cell - make treatment difficult w/o harming the host

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4
Q

way to defend against viruses

A

stimulate body to produce own Ab by vaccination

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5
Q

members of herpes group

A 
EBV 
herpes simplex
cytomegalovirus 
varicellazoster virus 
human herpes virus 6
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6
Q

herpes virus

A

double stranded DNA virus
large genome
latency

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7
Q

latency

A

ability to induce life long infection in host cell

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8
Q

selective toxicity

A

preferential inhibition of virus metabolism over host met

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9
Q

why is there no chemo for virus

A

use host

intracellular

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10
Q

nucleoside analogues

A

largest gp of antivirals

acyclovir, ganciclovir, zidovudine

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11
Q

alternative med for virus

A

vaccine
specific immunoglobulins
interferons

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12
Q

classification of viruses

A

small and large
small = fewer nucleotides = fewer virus specific genes
bigger virus = more proteins differ from host = more targets for drugs

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13
Q

importance of knowing virus lifecycle

A 
know the biochem processes that can be targeted 
eg infection into the cell
incorporation into the genome 
DNA replication 
viral protein production and packaging
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14
Q

what enzymes are targeted by acyclovir in herpes virus

A

thymidine kinase
DNA polymerase
different form the host form

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15
Q

how does acyclovir work

A

viral thymidine kinase high affinity to acyclovir
converts it to acycloGMP
and then acycloGTP by other cellular kinases
acycloGTP substrate for viral DNA polymerase
incorporated into DNA chain
3’ OH not available for phosphate bond = termination of the chain
a generation of new virus is prevented
acycloGTP poor substrate for cell DNA pol - host spared from potent effects

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16
Q

steps after acyclovir

A

acyclovir doesn’t cure - just suppresses by reducing the viral load
immune system eradicate completely

17
Q

when doesn’t the immune system work

A

immunosuppressed - HIV
immunosuppressed from drugs
antiviral treatment needed continually

18
Q

other uses of acyclovir

A

as zovirax for herpes cold sores

as prescription for Varicellar zoster virus - chicken pox

19
Q

virus life cycle

A 
virus attach - specific tropism 
cap seed protein and membrane of host cell 
penetrate cell
conf change 
fusion between phospholipid mem and mem of cell 
cap seed in cell 
DNA in cap seed 
uncoating 
DNA released 
hijack cell DNA 
replication
protein produced 
released outside
20
Q

concerns for acyclovir treatment

A

virus mutate - frameshift/nucleotide sub
viral thymidine kinase and DNA pol not present
drug not activated/virus DNA p not have higher affinity

21
Q

other ways to attack virus

A

conf change of membrane bilayer - no receptor
inhibit protein capsule breaking
enz break proteins made by virus
break protein coat - so virus cant attach to cell

22
Q

interferons

A

tell other cell to heighten immune response

23
Q

nucleoside

A

base and sugar

no phosphate

24
Q

double stranded DNA

A 
double helix 
H bond 
Watson and crick 
T and C pyrimidine 
A and G purine
major and minor grooves - major has histone 
antiparallel
25
Q

DNA replication

A 
DNA helicase unzips DNA - break H bond 
origin of replication 
dna pol works 5'-3' add nucleotide to 3'
leading strand cont
lagging - okazaki fragments until they meet each other 
DNA primase make RNA primer - need start point and temporary strand 
slider keeps DNA pol on chain 
nucleotides joined by ligase 
exonuclease break primer 
single stranded DNA binding protein 
semiconservative
26
Q

structure of acyclovir

A

base is guanine
nucleosides have nitrogenous base
acyclovir no sugar - not nucleoside - no OH to allow replication

27
Q

active compound of acyclovir

A

OH
thymidine kinase activates it
join to 3’ of DNA

28
Q

mode of action of acyclovir

A

competitively bind to viral DNA 3’ carbon

terminate replication

MCD Tutorials (9 decks)

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