Antivirals Flashcards
What surrounds the genetic material in viruses?
- Capsid (protein shell surrounding the genetic material)
- Lipid envelope and envelope proteins in larger viruses
What type of genetic material do the following viruses have:
1) Hepatitis B
2) Hepatits C
3) HIV
4) Herpes Simplex Virus
5) Influenza
1)
- Hepatitis B Hepadnavirus – it is a DNA virus that also involves reverse transcriptase in its replication
2)
- Hepatitis C - RNA virus
3)
- HIV - RNA - it’s a Retrovirus
4)
- Herpes Simplex Virus - DNA virus
5)
- Influenza - RNA virus
What is a virion?
- A completely formed virus that is active outside of a host cell
- Infective form with the RNA core and the capsid
Describe the relative curability of Hep B and Hep C
- Hep B – incurable
- Hep C – CURABLE
1) Define viral tropism
2) What is the tropism of Hepatitis A,B,C viruses?
1)
- Specificity of a virus for a particular host tissue, determined in part by the interaction of viral surface structures with host cell-surface receptors
2)
- Liver cells
At what point do you start treating someone who has recently got infected by Hep B or Hep C?
- When the infection becomes chronic
- The immune system, in some people, is able to clear Hep B and Hep C infections by itself
What is the treatment for Hep B? What type of drug is this? What is it often coadministered with?
- Tenofovir - Nucleotide reverse transcriptase inhibitor
- Peginterferon alpha (pegylated interferon)
What are the treatment options for Hep C? State the drug types
- Ribavirin (+ pegylated interferon)
- Ribavirin is a nucleoside analogue (purine analogue)
- Boceprivir – protease inhibitor (only works on Hep C genotype 1)
Describe the receptor interaction involved in HIV attachment and entry
- HIV GP120 binds to CD4 and CCR5 or CXCR4
- Then HIV GP41 penetrates the host cell membrane
- Viral capsid is endocytosed
State two drugs that interfere with HIV attachment and entry and state their targets
- Enfuvirtide – GP41
- Maraviroc – CCR5
Name 2 nucleoside reverse transcriptase inhibitors. How are they activated?
- Zidovudine
* Three step phosphorylation - Tenofovir
* Fewer activation steps
How do non-nucleoside reverse transcriptase inhibitors act? Give an example of an NNRTI
- Bind to the reverse transcriptase at an allosteric site and causes a change in shape of the enzyme so it blocks HIV replication
- Efavirenz
Give an example of an integrase inhibitor
- Raltegravir
1) What viral gene encodes all the viral structural proteins?
2) What must happen to the protein product of this gene, in order to produce fully functioning virus particles?
1)
- Gag gene
2)
- Gag gene encodes all viral structural proteins, starting with precursor proteins
- HIV protease cleaves Gag precursor proteins
- This allows the proteins to become functional
- Without this step, the virus would be ineffective
1) Name a drug that acts a protease inhibitor, the mode of action of protease inhibitors in treating HIV infection, and state one problem with its pharmacokinetics
2) What is it often coadministered with this Protease inhibitor drug and why?
1)
- Saquinavir
- It prevents the HIV protease enzymes which otherwise cleave the gag gene products which are precursors for viral structural proteins
- It has a low bioavailability
2)
- Ritonavir
- This decreases the metabolism of saquinavir
