CP3 - Antivirals Flashcards
what are the two types of viruses?
RNA virus and DNa virus
which viruses cause which types of infections?
RNA -acute
DNA - Chronic
(as a general rule)
why is there a distinction in timespan of infections caused by RNA and DNA viruses?
this is due to the lifespan of DNA and RNA
examples of acute infections caused by viruses
- influenza
- measles
- mumps
- hep A
when do antivirals need to be administered if they are to be effective?
for acute infections, if they are given soon after symptoms develop
examples of chronic latent viral infections
- herpes simplex virus
2. cytomegalovirus
examples of chronic persistent infections
- HIV
- Hep B
- Hep C
what are the cell constituents of viruses?
- nucleic acid (DNA/RNA)
- protein coat
- enzymes
- may to may not have a lipid envelope
what are the types of genes found in viruses?
- structural genes - for the functioning of the virus
2. non structural genes - take over the cell
what is the mechanism of replication of viruses?
- virus enters the body
- finds the cell
- attaches to a receptor and enters the cell
- uncoating of the virus
- viral enzymes produced using host machinery
- replication of enzymes
- transcription and translation of structural proteins
- assembly of new virus
- virus release
what do antivirals target and why?
viral proteins because these are unique to viruses and important for their infectivity and replication
why are DNA viruses slightly difficult to tackle?
their polymerases are likely to be the same as those in eukaryotic cells
(RNA to RNA polymerases are not found in our body)
what are the constituents of a nucleotide?
nitrogen base + ribose sugar +phosphate group
why may antivirals not be completely effective against viruses?
enzymes that facilitate viral replication are not highly accurate, and are therefore prone to mutations
what type of antiviral is azidothymidine?
nucleoside reverse transcriptase inhibitor
what are the 2 types of NRTIs?
purine analogues
pyrimidine analogues
name examples of purine analogues
analogues for adenine and guanidine - abacavir, tenofovir (end in vir)
name examples of pyrimidine analogues
thymidine analogue- zidovudine
cytosine analogue - lamivudine
(end in vudine)
which are the newer HIV drugs?
- fusion inhibitor
- integrase inhibitor
- chemokine receptor antagonists
why are some NRTIs effective against Hep B?
the virus contains a reverse transcriptase enzyme
what are NNRTIs?
non nucleoside reverse trascriptase inhibitors
how do NNRTIs work?
bind directly to the reverse transcriptase and work by non competitive inhibition
name examples of NNRTIs
efavirenz
nevirapine
what are the aims of HAART?
Highly active antiretroviral therapy aims to switch off viral replication. lifelong treatment
what substances are used to treat Hep C?
interferons and ribavirin are used, depending on virus genotype
what are interferons?
proteins released by animal cells in response to the entry of a virus, to inhibit its replication
what is aciclovir used against?
herpes simplex virus and varicella zoster
what type of drug is aciclovir?
nucleoside analogue
what is ganciclovir used against?
cytomegalovirus
what are oseltamivir and zanamavir used against? what type of antivirals are they?
influenza
neuraminidase inhibitors
what is ribavirin used against?
Hep C
Respiratory Syncytial Virus (RSV)
what are interferons used against?
Hep B
Hep C
