acyclovir Flashcards
what does acyclovir treat
herpes
effectiveness of acyclovir for herpes
reduction in relapse from 44% to 2%
virus features
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
way to defend against viruses
stimulate body to produce own Ab by vaccination
members of herpes group
EBV herpes simplex cytomegalovirus varicellazoster virus human herpes virus 6
herpes virus
double stranded DNA virus
large genome
latency
latency
ability to induce life long infection in host cell
selective toxicity
preferential inhibition of virus metabolism over host met
why is there no chemo for virus
use host
intracellular
nucleoside analogues
largest gp of antivirals
acyclovir, ganciclovir, zidovudine
alternative med for virus
vaccine
specific immunoglobulins
interferons
classification of viruses
small and large
small = fewer nucleotides = fewer virus specific genes
bigger virus = more proteins differ from host = more targets for drugs
importance of knowing virus lifecycle
know the biochem processes that can be targeted eg infection into the cell incorporation into the genome DNA replication viral protein production and packaging
what enzymes are targeted by acyclovir in herpes virus
thymidine kinase
DNA polymerase
different form the host form
how does acyclovir work
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
steps after acyclovir
acyclovir doesn’t cure - just suppresses by reducing the viral load
immune system eradicate completely
when doesn’t the immune system work
immunosuppressed - HIV
immunosuppressed from drugs
antiviral treatment needed continually
other uses of acyclovir
as zovirax for herpes cold sores
as prescription for Varicellar zoster virus - chicken pox
virus life cycle
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
concerns for acyclovir treatment
virus mutate - frameshift/nucleotide sub
viral thymidine kinase and DNA pol not present
drug not activated/virus DNA p not have higher affinity
other ways to attack virus
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
interferons
tell other cell to heighten immune response
nucleoside
base and sugar
no phosphate
double stranded DNA
double helix H bond Watson and crick T and C pyrimidine A and G purine major and minor grooves - major has histone antiparallel
