Tx, Prevention, Control of Viral Disease Flashcards
(35 cards)
Why are there fewer antivirals available than antibiotics?
Viruses are very dependent on the host cell and most agents that interfere with virus replication are toxic to the cell too
Which virus is Acyclovir typically used for?
Herpesvirus
Strucurally, Acyclovir is an analog of…
deoxyguanosine (guanine) but with no deoxyribose sugar
T/F. Acyclovir is administered as an active drug.
False. Inactive pro-drug –> requires enzymes in infected host cell to convert it to the active form
What is the mechanism of Acyclovir?
- It is incorporated into the growing DNA strand by viral DNA polymerase as if it were a G base and STOPS the growing of the viral DNA chain (b/c there is no attachment point for the insertion new nucleotides
- Causes competitive inhibition of viral DNA polymerase (by competing with dGTPs for viral DNA polymerase)
T/F. Acyclovir is toxic for uninfected host cell.
False. Nontoxic because needs viral enzymes to be incorporated into the host DNA
What converts the prodrug to acyclovir monophosphate?
virus induced thymidine kinase
How does Amantadine inhibit viral replication? Typically which virus?
Blocks viral uncoating
Influenza A
What is the mechanism of action of Amantadine?
Clogs the M2 ion channel!
-Causes viral RNA to remain bound to M1 –> virus cannot enter the nucleus –> viral replication is inhibited.
List 4 examples of Neuraminidase Inhibitors
Oseltamivir (Tamiflu)
Laninamivir
Zanamivir
Peramivir
T/F. NA and HA are major membrane glycoproteins in the nuclear membrane of influenza virus.
False.
Major membrane glycoproteins on the surface of influenza virus.
What is the normal action of neuraminidase in viral replication?
NA cleaves scialic acid and releases hemagglutinin so that the virus is freed from the infected cell
-allows virus to spread cell to cell
Mechanism of action of NA inhibitors?
Drugs block NA function and HA remains bound to scialic acid –> virus infection cannot spread
-inhibiting NA slows viral spread and allows the immune system to catch up and mediate the viral clearance
4 Targets for Anti-Retroviral Therapy
Inhibit…
1) protease
2) fusion
3) reverse transcriptase
4) integrase
What does NRTI stand for? What are 2 examples?
Nucleoside Analog Reverse Transcriptase Inhibitors
1) ZDV/AZT
2) ddI
Which drug is an analogue of Thymine?
ZDV/AZT
What is the mechanism of action of ZDV/AZT?
- competes with thymine for reverse transcriptase
- insertion of AZT-MP into cDNA blocks growth of cDNA transcribed from viral RNA by RT
What does ZDV have instead of an OH on its pentose sugar?
an azide (N3) group
Where does reverse transcription of viral genome happen and why?
- cytoplasm
- because RNA dependent DNA polymerase of virus (in cytoplasm) is 100x more sensitive to AZT/ZDV than celluar DNA polymerase (in the nucleus)
How to protease inhibitors work?
- by inhibiting proteases
- bind to active site of HIV protease and prevent the enzyme from cleaving the HIV polyproteins into functional proteins
- HIV can’t mature and noninfectious viruses are produced
4 Ws of Prevention
WHERE - endemic
WHO - population at risk
WHEN - if season, just before; outbreak in non endemic areas
WHY - loss caused by dz > cost of vax
What is attenuation?
When the viral antigenicity is maintained, but the virulence is destroyed. Therefore, the virus is handicapped and cannot cause disease but can cause antibody production.
Which species was used for serial passage of the Rinderpest virus to produce an attenuated virus?
Rabbits
What is a cold-adapted mutant?
A virus that replicates at lower temperatures (i.e. - 33C and NOT 37C) - they are safer
-Typically intra-nasal: may cause mild nasal infection, but antibodies are made against the more severe lower respiratory disease as well
