Antiviral Drugs

Question 1

What are the 3 main types of antiviral drugs

Answer 1

Drugs that target viral enzymes (rational drug design - development of small molecules which block specific enzyme from working)
Nucleoside analogues - chemically altered nucleoside which is inserted into the viral genome and interferes with viral replication
Directly acting antivirals - target specific viral factors

Question 2

Whta is Acyclovir

Answer 2

Is a nucleoside analogue: has no 3 prime hydroxyl group, preventing phosphodiester bond formation
given in unphosphorylated form. Requires viral thymidine kinase to phosphorylate it (needs to be phosphorylated to be entered into virus DNA)
This kinase can only be found in Herpes virus infected cell –>: specificity of acyclovir activation and action

Question 3

What is Remdesivir

Answer 3

Analogue of adenosine, causes chain termination 3 nucleotides downstream of incorporation -n twists the shape of the molecule so nucleosides cannot be added
effective against SARS CoV2

Question 4

What is Amantadine

Answer 4

Antiviral for Influenza
Sits in the M2 ion channel in the virus wall
Normal function of M2 ion channel: when virus is in endosome, channel allow protons from acidic environment of endosome to enter in the virus particle. This disrupts the disrupts interactions between matrix protein and nuclear protein holding virus together so virus is “uncoated” and releases its genome into the host cell.
Amantadine sits in M2 channel blocking the entry of protons

Question 5

What are neuraminidase inhibitors

Answer 5

Antivirals for Influenza
Enzyme inhibitor
Neuraminidase stop newly formed virion binding to host receptor via H.A. Inhibitor stops cleaving of sialic acid so virion is not released
NAI’s : Oseltamivir (Tamiflu) and Zanamivir (Relenza)

Question 6

what is the mutation that causes influenza to be resistant to Oseltamivir

Answer 6

Histamine to Tyrosine change at position 274

Question 7

What is Baloxavir

Answer 7

Antiviral for Influenza
Enzyme inhibitor
Embeds into PA endonuclease (subunit of viral polymerase)

Question 8

Why are people taking HIV antivirals not cured

Answer 8

HIV is a retrovirus so it integrates its genomic sequnce material into the DNA of the host cell so even when the viral load is controlled. by antivirals, there is still a HIV resevoir/ new HIV virions can still be produced

Question 9

How should infection be treated differently early vs later?

Answer 9

Early = control virus and virion production
Later = control damage the virus has stimulated (damage is largely done by our own immune system)

Question 10

What are Biologics

Answer 10

Passive immunotherapy- antibodies taken from recovered individuals, or produced from immortalized B cells.
eg Palivizumab against RSV for infants – a humanized monoclonal antibody against the F protein