Antivirals Flashcards
(46 cards)
What is an incubation period?
The period between when someone is expsosed to the infection, to when they develop their first symptom
What is clinical latency?
When the patient is asympomatic and well, but the virus is present within their body
What is ‘atripla’?
Atripla is an antiviral medication that prevents the HIV virus reproducing within your body
What type of infection do RNA viruses tend to cause?
Acute infection
HOWEVER, Both HIV and Hep C are RNA viruses but are actually chronic.
What type of infection do DNA viruses tend to cause?
Chronic infection
3 examples of RNA virsuses:
Influenza
Measles
Mumps
Hep A
Does infleunza cause a chronic or acute infection and is it a RNA or DNA virus?
RNA
Acute
3 Examples of chronic infections:
HIV (but RNA virus)
Hep B
Hep C (but RNA virus)
Why is HIV unique?
HIV is unique because it uses reverse transcriptase step in its replication so the RNA goes to double stranded DNA and this then gets integrated into the hosts DNA.
Viruses will structurally have…
Contain nucleic acid either in the form of DNA or RNA
Have a protein coat
May have a lipid envelope
What does the non-structural genes within viruses code for?
They encode for proteins responsible for taking over the host. This genes code for the viral enzymes such as protease, reverse transcriptase, integrase etc.
How do viruses replicate?
They attach to the cell via a receptor
They then enter the cell without harming it
They make ‘early proteins’, such as non-structural proteins (like enzymes they need for replication so they can replicate the viral genome in order to take over the cell)
Replication occurs
Late transcription/Translation occurs (viral structural proteins are formed to make the virus)
The virus is released and occasionally the virus kills the cell
What are the 2 types of antivirals that tend to target polymerases?
Nucleoside reverse transcriptase inhibitors
OR
NON-nucleoside reverse transcriptase inhibitors
How do antivirals against polymerases work?
They tend to mimic the nucleotides which are used in the RNA/DNA.
How does Azidothymidine (AZT) work?
It targets polymerases.
It is a nucleoside reverse transcriptase inhibitor (NRTI)- so inhibits reverse transcriptase
It works by terminating the RNA/DNA chain by interfering with polymerase so that it can not keep building the genome chain.
It is now used as a HIV drug, as it inhibits HIV replication
Problem: resistance against AZT develops rapidly
Purine bases are:
Adenine
Guanidine
Pyramidine bases are:
Thymine
Cytosine
Zidovudine is a….
Thymidine analogue and can be used to treat HIV
Lamivudine is a….
Cystosine analogue and can be used to treat HIV
Can also work against the Hep B virus
However, M184V mutation in the reverse transcriptase results in complete resistant to Lamivudine
Abacavir and Tenofovir are…..
Purine (so adenine and guanidine) analogues and can be used to treat HIV
Note: tenofovir can also work against the Hep B virus
How do non-nucleoside reverse transcriptase inhibitors work?
they bind to different parts of the polymerase as NRTI do in order to inhibit it. However, they have the same result.
Why are protease good for antivirals to target?
- As part as their replication, viruses often encode for their own unique proteases. They need these because they run off very large polyprotein molecules from the RNA so they sometimes require extra proteases to cut these up and make these into enzymes.
- Since these types of proteases are unique to viruses, if we inhibit those then we do not get toxicity.
What is the common suffix for protease inhibitors?
-VIR
Examples: Atazanavir Darunavir Fospamprenavir Lopinavir Nelfinavir Ritonavir- this actually boosts the levels of other protease inhibitors by inhibiting the liver enzymes. For these reasons you use ritonavir alongside the other drugs. - Saquinavir
What does the integrase enzyme do?
It is a enzyme unique to HIV that allows the virus to integrate into the host genome.
