Antiviral Drugs

Question 1

List the 6 stages in the life cycle of viruses.

Answer 1

1. Attachment
2. Penetration into host cell
3. Uncoating and targeting
4. Gene expression
5. Virion assembly/maturation
6. Release of new infectious viruses

Question 2

List 2 ways in which viruses penetrate the host cell.

Answer 2

Endocytosis

Direct membrane fusion

Question 3

List 2 ways in which viruses can be released from the host cell.

Answer 3

Host cell lysis

Budding (NOTE: doesn’t necessarily kill the host cell)

Question 4

What are the 3 main targets in the life cycle of a virus which are targeted by antiviral drugs?

Answer 4

Attachment/entry into host cells
Breakdown of the virion within the cell
Virus release from host cells

Question 5

When would we use antiviral drugs? Consider:

a) Acute/relapsing infections (3)
b) Chronic active infections (2)

Answer 5

ACUTE:
Influenza
Herpes virus (herpes simplex, varicella zoster, cytomegalovirus)
Respiratory syncytial virus (RSV)

CHRONIC:
HIV
Hepatitis virus (B, C)

Question 6

List the 2 main classes of antiviral drugs.

NOTE: there are many more than this - but most of these are specialist drugs, so you don’t need to know about them at this level!

Answer 6

Aciclovir

Neuraminidase inhibitors

Question 7

List 3 examples of neuraminidase inhibitors.

Answer 7

Oseltamivir
Peramivir
Zanamivir

Question 8

Which 2 viruses is aciclovir used for?

Answer 8

Herpes simplex virus (types 1 and 2)

Varicella zoster virus

Question 9

Describe the mechanism of action of aciclovir. (3)

Answer 9

1. Viral thymidine kinase converts aciclovir into aciclovir monophosphate
2. Cellular guanylate kinase converts this into aciclovir diphosphate
3. Pyruvate kinase converts this into aciclovir triphosphate
   a. This inhibits viral DNA polymerase
   b. This inhibits viral DNA replication

Question 10

List the adverse effects of aciclovir. Consider adverse effects at:

a) Low dose (1)
b) High dose (2)

Answer 10

LOW DOSE:
Generally well tolerated

HIGH DOSE:
Renal tubular crystalosis
Seizures

Question 11

Give 1 example of when high dose aciclovir is used.

Answer 11

Encephalitis

Question 12

Describe the mechanism of action of neuraminidase inhibitors. (2)

Answer 12

1. Inhibits neuraminidase, which cleaves sialic acid groups from glycoproteins
2. This inhibits viral budding and viral replication

Question 13

Which virus is affected by neuraminidase inhibitors?

Answer 13

Influenza

Question 14

List 2 adverse effects of neuraminidase inhibitors.

Answer 14

GI toxicity

Neuropsychiatric symptoms

Question 15

List 9 broad categories of types of antivirals.

Answer 15

1. Nucleoside reverse transcriptase inhibitors
2. Non-nucleoside reverse transcriptase inhibitors
3. Protease inhibitors
4. Viral DNA polymerase inhibitors
5. Inhibitors of HIV fusion with host cells
6. Neuraminidase inhibitors
7. Integrase inhibitors
8. Chemokine receptor antagonist
9. Biopharmaceuticals