Principles of Anti-Viral Chemotherapy Flashcards Preview

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Flashcards in Principles of Anti-Viral Chemotherapy Deck (30)
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1
Q

What are anti-viral agents mainly used for?

A

To control those viral infections with high morbidity and mortality

2
Q

What is the problem with anto-viral chemotherapy?

A

They are still developing, and some serious viruses still have no specific therapy

3
Q

What does the life cycle of a virus provide?

A

Numerous target steps for anti-viral drugs to act on to prevent the infection and spread of the virus

4
Q

What steps of the viral life cycle can be used as targets?

A
  • Adsorption onto the surface of the host cell via attachment
  • Penetration into the cell via fusion with the plasma membrane and then entry via the endosome
  • Uncoating of the viral DNA so that it can be made available for interaction with the host cell DNA
  • Viral proteins synthesis by host cell
  • New viruses are released from cell via lysis or budding
5
Q

Draw a diagram illustrating the viral life cycle

A
6
Q

What are the main classes of anti-viral drugs?

A
  • Nucleoside analouges
  • Amantadine
  • Highly active anti-retroviral therapy (HAART)
7
Q

How do nucleoside analogues work?

A

They are taken up into the cell and converted to a form of nucleoside that will prevent any further synthesis of viral proteins in the cell by inhibiting RNA polymerase

8
Q

Give two examples of nucleoside analogues

A
  • Aciclovir
  • Ganciclovir
9
Q

What is aciclovir used against?

A

HSV and VZV

10
Q

What is the mechanism of action of aciclovir?

A

It is converted to a monophosphate form upon entering the cell by the viral enzyme thymidine kinase. This is then converted to triphosphate form by the host which inhibits the action of RNA polymerase

11
Q

What is the advantage of aciclovirs mechanism of action?

A

It is only potent against virally infected cells

12
Q

What is the mechanism of action of ganciclovir?

A

It is coverted to a triphosphate form and the resulting guanosine triphosphate inhibits any further protein synthesis

13
Q

What is ganciclovir used for?

A

CMV infections, especially in immunocomprimised individuals

14
Q

How does amantadine work?

A

Prevents the uncoating and release of viral DNA

15
Q

What is the problem with amantadine?

A

Viral resistance is developing quickly

16
Q

What is the result in the rapid growth of viral resistance to amantadine?

A

Only short courses are used to prevent disease

17
Q

What is HAART used against?

A

HIV infections

18
Q

What has HAART been shown to do?

A

Decrease the viral load and maintain CD4+ levels for a significant period of tiem

19
Q

Give 3 examples of HAARTs

A
  • Nucleoside reverse transcriptase inhibitors (NRTIs)
  • Non-nucleotide reverse transcriptase inhibitors (NNRTIs)
  • Protease inhibitors
20
Q

What are NRTIs?

A

Nucleoside analogues that are converted to 5’-triphosphate derivatives in the cell

21
Q

How do NRTIs work?

A

Once incorporated into the viral DNA chain, they inhibit any further growth

22
Q

What is the main example of NRTIs?

A

Zibovudine

23
Q

What is zibovudine an analouge of?

A

Thymidine

24
Q

What do NNRTIs do?

A

Inhibit NRTIs

25
Q

What are the main examples of NNRTIs?

A
  • Nevirapine
  • Delaviridine
26
Q

What are the most effective anti-retroviral compounds?

A

Protease inhibitors

27
Q

How do protease inhibitors work?

A

By inhibiting the action of protease enzymes which are only found in virally infected cells, which will normally convert polyproteins (from mRNA) of the virally infected cells into viral proteins

28
Q

Give two examples of protease inhibitors

A
  • Atazanivir
  • Indinavir
29
Q

When does HAART work best?

A

When all the therapies are used concurrently

30
Q

What are the main limitations of antiviral therapy?

A
  • The narrow spectrum of activity
  • The low therapeutic values (before side effects set in)
  • Drug resistance may occur