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Flashcards in Antiviral therapy Deck (63)
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1

Where can anti-viral drugs intervene in the life-cycle of a virus?

- Docking on
- Membrane fusion, escape from the vacuole, uncoating
- Replication of DNA/RNA
- Integration of DNA into the genome
- Translation of viral RNA to protein
- Assembly and maturation of virions
- Escape from the host cell
ALSO can work by enhancing immune response

2

What kind of viruses do not integrate their genetic code into the genome of the cell?

Pox viruses

3

What is the enzyme called that encorporates the virus' genetic code into the host cell's genome?

Integrase

4

What viruses is Aciclovir (and valaciclovir) effective against?

- Herpes Simplex Virus 1
- Herpes Simplex Virus 2
- Herpes Zoster virus

5

What are aciclovir and valaciclovir analogues of?

Guanosine (it is acyclo-guanosine)

6

What is aciclovir converted into?

- Converted by the viral thymidine kinase to monophosphate acyclo-GMP
- Human enzyme converts it to a triphosphate
- Then used by DNA polymerase
- Viral DNA polymerase used far more readily than the human and causes chain terminations

7

How can aciclovir and valaciclovir be administered?

- Topically (e.g cold sores or to the eye)
- Orally
- IV

8

What are some side-effects of aciclovir and valaciclovir?

- Cotard's syndrome (belief that one is already dead)
- Overdose may lead to lethargy, confusion and myoclonus

9

What has greater oral bioavailability aciclovir or valaciclovir?

Valaciclovir

10

How does resistance occur to aciclovir or valaciclovir?

Via mutation of the viral thymidine kinase and/or DNA polymerase

11

What is idoxuridine used for?

Herpes keratitis (too toxic for systemic use)

12

What was the original treatment for Hep C?

- Ribavirin (now only occasionally used, cheaper)
- Pegylated interferon (interferon alpha or beta)

13

What drugs are active against CMV?

- Ganciclovir
- Valganciclovir

14

What are side-effects of ganciclovir and valganciclovir? (anti-CMV drugs)

Bone marrow suppression

15

How does ganciclovir function?

- Synthetic analogue of deoxyguanosine
- It is phosphorylated to the monophosphate by a CMV thymide kinase and then to the triphosphate by cellular kinases
- It inhibits viral DNA polymerase more than cellular DNA polymerase, by being incorporated and acting as a chain terminator

16

What is the difference between valganciclovir and Ganciclovir?

- Valganciclovir is a valine ester of ganciclovir
- Valganciclovir has greater oral bioavailability

17

What specific enzyme do retroviruses contain?

Reverse transcriptase

18

How do nucleoside and nucleotide analogues (NRTIs) function?

They inhibit reverse transcriptase by being incorporated into the growing DNA chain and then being unable to link to the subsequent base

19

What is an example of a nucleoside analogue?

Lamivudine

20

How many phosphorylations do nucleoside analogues (such as lamivudine) require for incorporation?

3

21

What viruses can lamivudine be used to treat?

Hep B and HIV

22

What is lamivudine an analogue of?

Cytidine

23

What are some adverse effects of lamivudine?

- Nausea
- Diarrhoea
- Fatigue
- Headaches
- Cough
- Pro-inflammatory response
- Autoimmunity

24

How many phosphorylations are required for nucleotide analogues (e.g Tenofovir) to become incorporated?

2

25

Give an example of a nucleotide analogue that is used in the treatment of Hep B

Tenofovir

26

What is tenofovir an analogue of?

Adenosine monophosphate

27

What are adverse effects of tenofovir?

- Renal insufficiency
- Fanconi syndrome

28

How do non-nucleoside/nucleotide reverse transcriptase inhibitors (NNRTIs) function? (e.g Efavirenz)

They bind to reverse transcriptase enzyme but not at the active site - this hampers its activity by distortion etc.

29

Give an example of a non-nucleoside/nucleotide reverse transcriptase inhibitor? (NNRTIs)

Efavirenz

30

How do protease inhibitors (e.g darunavir, ritonavir) function?

They act by binding viral protease that cuts viral precursor proteins into the components of virion structure