10 Antiviral Vaccines And Chemotherapy Flashcards
What is the difference between passive and active immunisation?
Passive immunisation relies on administration of antibodies, occurs often after infection, with no production of an immune response on their own and being a short term solution.
Active immunisation however administers the antigen, prevents future infection, produces own antibodies and remembers and is a long term solution.
How are viruses attenuated?
A virus is attenuated by introducing it into a species with which it does not replicate well or by forcing it to replicate repeatedly in tissue culture which is a protocol called passaging.
Describe the actions of adjuvants, why are they used?
Adjuvant means ‘to help’ and is added to a vaccine to enhance immunogenicity. Some vaccines require adjuvants to stimulate innate response so that adaptive immunity can be initiated.
List and describe four vaccine types
Traditional vaccines ,, inactivated vaccines, destroy the ability to infect and keep antigenicity
Protein vaccines ,, subunit vaccines, isolate a protein or carbohydrate from organisms for vaccines
Gene based vaccines ,, viral vectors, adenovirus vector, a virus which is either harmless or made harmless or made harmless by genetic engineering to have a specific antigen, mRNA vaccines
What are the advantages of the mRNA and Adenovirus vaccines
They both elicit an immune response and neither need adjuvants
List and describe three points of action of antiviral drugs
- Binding to free viral particle
- Virucidal compounds destroy the virus and interfere with attachment
- Inhibition of virus coating
What are ‘prodrugs’ and what advantages do they have?
Antiviral prodrugs have a chemical side group attached to active antiviral molecule, they enhance absorption and tissue penetration. The hose enzymes cleave off the side group and release an active drug and thus a higher concentration of the active drug is achieved.
Aciclovir is active in cells infected by Herpes viruses and not in uninflected cells, why?
The higher concentration of the active triphosphate metabolite in infected cells plus the affinity for viral polymerases result in the low toxicity of acyclovir in non-infected host cells.
What are the current anti-HCV drugs directed against and how do they work?
Most are directed against NS5a/NS5b or NS3/4A
NS5 - RNA dependant RNA polymerase
NS3/4A protease
Human cells do not produce these enzymes and inhibits enzymes so they don’t function
Describe the action of Amantadine in influenza infections
M2 protein acts as ion channel across viral membrane and hydrogen ions enter the virus causing low pH which causes disassociation of core proteins to bind RNA. The RNA can then exit virus’ and into the cell nucleus to replicate and block the ion channel by binding M2 prevents hydrogen ions entering the virus so there is no reduction of pH and subsequent un-coating.
What is HAART?
Highly Active Antiretroviral Therapy
It is a recent strategy for HIV treatment to use combinations of drugs
Briefly explain the role of interferons as anti viral agents
Potent, glycoprotein cytokines associated with complex antiviral, immunodulating and anti-actions (response to infection)
Describe the action of AZT on HIV
Potent inhibitor of reverse transcription by binding the reverse transcriptase enzyme
Also prevents nuclear chain elongation by stopping nucleotide addition
Describe the actions of fomivirsen
- Single stranded DNA complementary to viral mRNA
- DNA and mRNA bind to each other and prevent translation
- Administered directly into the eye
