8.14_Antivirals Flashcards
Targets of antivirals
penetration, uncoating, genome replication, RNA synthesis, protein synthesis, re-assembly, release from host
Common Herpes Rash
presents with a vesicular rash on an erthematous base
Acyclovir
treats HSV-1 and 2 well, is also drug of choice for VZV, is an analogue of deoxyguanosine and will be incorporated into genome as replication occurs therefore ending the replication,
it is activated in a cell with virus by a viral thymidine kinase that phosphorylates it, this is what makes it specific to viral cells
It also has greater affinity for viral polymerase
What is more toxic antibiotics or antivirals?
Antivirals are more toxic because virals use so much of host cell machinery that it is hard to differentiate or be specific in attack
Valacyclovir and Famciclovir
These are two modifications of acyclovir and are used for oral therapy. They have modification that makes them have a much higher bioavailability and be better absorbed in GI tract, these are considered a prodrug while acyclovir is not
Often used for prophylaxis and treatment but severe infections need acyclovir too
How to treat latent herpes viruses?
These cannot be treated with acyclovir or the others because there is nothing replicating. Latency means the virus is hanging out in a nerve cell and not doing anything so antivirals have no effect, must wait until prodromal phase reappears
Ganciclovir
Similar to ancyclovir, but phosphorylated by a cellular kinase so it is less specific. used in treatment of cytamegalovirus, also has a pro drug called valganciclovir
Resistance to Herpes virus Antivirals
Can occur due to mutations in the viral thymine kinase or the viral polymerase, but in regular immuno patients it is uncommon,
Adamantanes
group of antiinfluenze drugs, this group inhibits the M2 protein that is in charge of uncoating the virus when it enters a host, these are good for flu A but not flu B
Adamantanes examples
Amantadine and Rimantadine are both examples of an adamantane, they target the M2 and prevent uncoating and release of virus in a cell
Neuraminidase inhibitors
class of anti influenzas that target the enzyme neuraminidase which helps cleave the virus from the cyalic linkage to the host when it is trying to leave, so if inhibited you will get a collection of viruses attached to outside of host
Target flu A and B
Neuraminidase examples
Oseltamivir and Zanamivir Peramivir and Laninamivir
Resistance to Neuraminidases and side effects
very easy for cells to make new neuraminidases so they drugs do not work anymore, side effects often include some neuropsych issues
These also dont provide a great reduction in duration of disease only about 1.3 days and fever also down for only about 1 day
Ribavirin
Nucleoside analogue with antiviral activity, used to treat infants with RSV through aerosol treatment, can also treat some funky things like lassa fever, side effect is anemia
What does a retrovirus need to bring into a host?
A reverse transcriptase to make the DNA intermediate
A viral polymerase to transcribe
