Anti-virals Flashcards
Describe the generic structure of a virus
Genetic material (RNA and DNA)
Surrounded by capsid (protein shell surrounding the genetic material of the virus)
Lipid envelope with envelope proteins embedded
What is the tropism of viral hepatitis
Liver hepatocytes
What is the treatment of hepatitis B
Only chronic infection required treatment
Tenofovir - nucleotide analogue, given sometimes with Peginterferon alfa
What is the treatment of Hepatitis C
Only chronic infection required treatment
Ribavirin + Peginterferon alfa
Ribavirin - nucleoside analogue prevents viral RNA synthesis (purine analogue)
Boceprevir - protease inhibitor
Most effective against Hep C genotype 1
What is the goal of hepatitis C treatment and what does the combination of drugs depend on
Cure the virus
HCV genotype (genetic structure of the virus)
viral load
past treatment experience
degree of liver damage
ability to tolerate the prescribed treatment
need for liver transplant
Describe the life cycle of HIV
- Viral membrane proteins interact with leukocyte membrane receptors
- Viral capsid endocytosis
- Within cytoplasm - reverse transciptase enzyme converts viral RNA to DNA
- DNA transported into nucleus and integrated into host DNA using integrate
- Host cell’s ‘machinery’ utilised to produce viral RNA and essential proteins
- Virus is assembled within cell 7. mature virion is released
Which receptors are invoked in attachment and entry of HIV viral particles
HIV Glycoprotein (GP)120 attaches to CD4 receptor
GP120 also binds to either CCR5 or CXCR4
GP41 penetrates host cell membrane and viral capsid enters
Give examples of antivirals that target the attachment and entry of HIV viral particles and state their specific targets
Enfuvirtide
Binds to HIV GP41 transmembrane glycoprotein
Maraviroc
Blocks CCR5 chemokine receptor
What types of drugs target the replication of HIV in the host cell
Nucleoside RT inhibitors
Nucleotide RT inhibitors
Non-nucleoside RT inhibitors
Describe Nucleoside RT inhibitors and give an example of one
Activated by 3 step phosphorylation process
E.g. Zidovudine
Describe Nucleotide RT inhibitors and give an example of one
Fewer phosphorylation steps required
E.g. Tenofovir
Describe non-Nucleoside RT inhibitors and give an example of one
No phosphorylation required
Not incorporated into viral DNA
E.g. Efavirenz
Give an example of an integrate inhibitor
Raltegravir
Which precursor encodes all viral structural proteins
Gag precursor
HIV protease cleaves Gag precursor protein
Giv an example of a protease inhibitor
Saquinavir - 1st generation PI
Low dose Ritonavir reduces PI metabolism - co-administered as ‘booster’
What are the targets in the HIV replication cycle for anti-virals
HIV entry
HIV replication
HIV integrase
HIV protease
Describe the virology of herpes simplex
Double-stranded DNA
Surrounded by tegument and enclosed in a lipid bilayer
Describe the tropism of herpes simplex
Herpes Simplex Virus (HSV)-1 - cold-sores
HSV-2 - genital herpes
What is used to treat herpes simplex
Nucleoside analogues - Aciclovir
Describe the virology of influenza
Multipartite single stranded RNA virus
Envelope protein neuraminidase - release
What is the tropism of influenza
Nose, throat and bronchi
What is used to treat influenza
Neuraminidase inhibitor e.g. Oseltamivir (tamiflu)
Distinguish between different types of virus and describe how they use the host cell to replicate
HIV - Retrovirus, leukocytes
Hepatitis - DNA + RNA viruses, hepatocytes
Herpes Simplex - DNA virus
Influenza - RNA virus
Summarise the mechanisms of action of antiretroviral drugs + examples
Entry inhibitors - Enfuvirtide + Maraviroc
RT inhibitors - Nucleoside analogues (Zidovudine), Non-nucleoside analogues (Efavirenz)
Integrase inhibitors - Raltegravir
Protease inhibitors - Saquinavir
