Anti Virals Flashcards
Viral physiology: summarise how viruses use the host cell to replicate
Anti-viral drugs: summarise the mechanisms of action of anti-viral drugs used in the treatment of HIV, hepatitis, herpes and influenza
Distinguish between different types of virus and describe how they use the host cell to replicate
Summarise the mechanisms of action of antiretroviral drugs
Describe the actions of other antiviral drugs
-
Describe the general structure of the virus
- contains genetic material = RNA / DNA
- -> within a capsid
- which is then encapsulated by lipid envelope
- on lipid envelope layer, there are envelope proteins projecting out
Describe drugs used to treat Viral Hepatitis:
a) Tropism
b) Hep B
c) Hep C
–> only chronic infections require treatment
a) Tropism
b) Hep B
- Tenofovir
- -> Nucelotide analogue
- -> given sometimes with + peginterferon alfa
c) Hep C
- Ribavirin + peginterferon alfa
- -> Ribavirin = nucleoside analogue
- -> prevents viral RNA synthesis
- Boceprevir
- -> protease inhibitor
- -> Most effective against Hep C genotype 1
Describe the HIV life cycle
- Attachment & Entry
- -> Viral membrane proteins interact with leukocyte membrane receptors
- -> Viral capsid endocytosis
HIV Glycoprotein (GP)120 attaches to CD4 receptor
- GP120 also binds to either CCR5 or CXCR4
- GP41 penetrates host cell membrane & viral capsid enters
- Replication & Integration
- -> Within cytoplasm - reverse transciptase enzyme converts viral RNA –> DNA
- -> DNA transported into nucleus & integrated into host DNA
replication = Viral single-stranded RNA –> double stranded DNA by reverse transcriptase
Integration = Viral integrase inserts viral DNA into host DNA
- Assembly & Release
- -> Host cell’s ‘machinery’ utilised to produce viral RNA & essential proteins
- -> Virus is assembled within cell –> mature virion is released
Gag precursor –> encodes all viral structural proteins
HIV protease cleaves Gag precursor protein
For HIV Entry Inhibitors, how do antiretrovirals target the process of attachment and entry?
a) Enfuvirtide
- Binds to HIV GP41 transmembrane glycoprotein
(attachment inhibitor)
b) Maraviroc
- Blocks CCR5 chemokine receptor (core receptor of HIV)
For HIV replication inhibitors, how do retrovirals target the process of HIV replication ?
a) Nucleoside RT inhibitors
Activated by 3 step phosphorylation process
E.g. Zidovudine
b) Nucleotide RT inhibitors
Fewer phosphorylation steps required
E.g. Tenofovir
c) Non-nucleoside RT inhibitors
No phosphorylation required
Not incorporated into viral DNA
E.g. Efavirenz
For HIV integrase inhibitors, how do retrovirals target the process of HIV integration ?
a) Integrase inhibitors
e. g Raltegravir
For HIV protease inhibitors, how do retrovirals target the process of HIV Assembly + release ?
Protease inhibitors (PI) = e.g Saquinavir
–> Low dose Ritonavir reduces PI metabolism –> co-administered as ‘booster’
ADV = no transmission of HIV through unprotected sex
Describe the Herpes Simplex Virus
- double stranded DNA virus
- enclosed in a lipid bilayer
2 types
HSV 1 –> cold sore
HSV 2 –> genital herpes
Influenza
- single stranded RNA Virus
- envelope protein neuraminidase –> releases virus –> allows transmission
SUMMARY 1
Distinguish between different types of virus and describe how they use the host cell to replicate
a) HIV - Retrovirus, leukocytes
b) Hepatitis - DNA & RNA
viruses, hepatocytes
c) Herpes Simplex - DNA virus
d) Influenza - RNA virus
-
SUMMARY 2
Summarise the mechanisms of action of antiretroviral drugs
a) Entry inhibitors - Enfuvirtide & Maraviroc
b) RT inhibitors - Nucleoside analogues (Zidovudine), Non-nucleoside analogues (Efavirenz)
c) Integrase inhibitors - Raltegravir
d) Protease inhibitors - Saquinavir
-
What are the treatment methods of HSV ?
Nucleoside analogues –> Aciclovir
What are the treatment methods of Influenza ?
Neuraminidase inhibitor –> Oseltamivir
effective = VACCINE
