Antivirals Notes

Question 1

1) All antivirals are ……

2) No antivirals are ……

Answer 1

1) All are virustatic

2) None are virucidal

Question 2

What type of intracellular parasites are viruses?

Answer 2

obligate intracellular parasites

Question 3

Finish the sentence: As viruses utilise host cell enzymes to replicate……

Answer 3

….there are limited viral proteins that are targets for drugs

Question 4

What is a common side effect to host cells?

Answer 4

toxicity to host cell

Question 5

Are antivirals used in a) a minority or b) a majority of viral infections?

Answer 5

MINORITY

Question 6

Antivirals a) DO b) DO NOT

eradicate virus from latently infected cells (Herpes)

Answer 6

b) DO NOT

Question 7

True or False: Several stages of the life cycle are targets for antivirals (intracellular stages)?

Answer 7

TRUE

Question 8

Do antivirals have a greater effect on a) host cell function or b) viral replication?

Answer 8

b) Viral replication

Question 9

Most antivirals are what type of analogues?

Answer 9

nucleoside analogues

Question 10

What do nucleoside analogues do?

Answer 10

they inhibit nucleic acid synthesis

Question 11

Types of antiviral therapy:

What is prophylaxis?

Answer 11

To prevent infection

Question 12

What is pre-emptive therapy?

Answer 12

It is when there is evidence of infection detected before symptoms

Question 13

Name 4 types of antiviral therapy:

Answer 13

1) Prophylaxis
2) Pre-emptive therapy
3) Overt disease
4) Suppressive therapy

Question 14

What is suppressive therapy?

Answer 14

it keeps viral replication below rate at which tissue damage occurs in an asymptomatic infected patient (HIV)

Question 15

What is overt disease? (This wasn’t in notes)

Answer 15

A host-parasite interaction that results in some injury to the tissues of the host. (This was not in notes)

Question 16

Antivirals for HSV: With what types of presentations of HSV are antivirals used?

Answer 16

• Mucocutaneous: Oral/ Genital/ Eye/ Skin
• Encephalitis
• Immunocompromised- any site

Question 17

When are antivirals used in someone who presents with chickenpox (VZV)?

Answer 17

• When it affects neonate/ immunocompromised/ pregnant

- Immunocompromised adult: only effective if the treatment is begun within 24h

Question 18

When are antivirals useful in someone who presents with shingles (VZV)?

Answer 18

only decreases post-herpetic neuralgia in immunocompetent host if begun within 72h

Question 19

Name some of the antiviral treatments and their route of administration in HSV + VZV:

Answer 19

• Aciclovir: Oral/ IV/ Eye ointment/ cream
• Valaciclovir: Oral
• Famciclovir: Oral
• Foscarnet: IV

(Aciclovir like drugs are only active in herpes infected cells (low toxicity for normal cells) )

Question 20

Describe Aciclovir’s mode of action: (4 points)

Answer 20

• Aciclovir is converted by viral thymidine kinase to ACVMP
• ACVMP then converted by host cell kinases to ACV-TP
• ACV-TP in turn completely inhibits + inactivates HSV-specific DNA polymerase
• Preventing further viral DNA synthesis without affecting normal cellular processes

Question 21

Antivirals + CMV ( cytomegalovirus):
-All available drugs for CMV have significant toxicity,
when should antivirals be used to treat CMV?

Answer 21

• Only treat life/ sight threatening CMV infections

- May be used to treat neonates with symptomatic congenital CMV infection

Question 22

Name 4 antivirals used in the treatment of CMV and give their routes of administration:

Answer 22

• Ganciclovir: IV/ ocular implant
• Valganciclovir: Oral
• Cidofovir: IV
• Foscarnet: IV

Question 23

Antivirals+ HIV: What is the type of antiviral therapy used in HIV?

Answer 23

Combination anti-retroviral therapy (cART)

Question 24

How has cART transformed HIV care?

Answer 24

• Restoration of immune function in AIDS

- Decrease in opportunistic infections

Question 25

What are the antivirals used for chronic Hepatitis B?

Answer 25

• Pegylated interferon alpha (subcutaneous)

* Nucleoside analogues – Tenofovir / Adefovir / Entecavir / Lamivudine / Emtricitabine/ Telbivudine

Question 26

What is the length of time antivirals are used for in Chronic Hepatitis C?

Answer 26

often 12-48 weeks

Question 27

What are the 2 antiviral therapies used for Chronic Hepatitis C?

Answer 27

oPeglycated interferon alpha (subcutaneous) + ribavirin (oral)

oAs above plus protease inhibitor (telaprevir / boceprevir)

Question 28

In what respiratory infections are antivirals used?

Answer 28

• Influenza A / B

- Respiratory Syncytial Virus

Question 29

State the antiviral treatment used in Influenza A / B:

Answer 29

• Oseltamivir (Tamiflu) or Zanamivir

o Role in both treatment + prophylaxis

o Should start within 48 hours of symptom onset / contact

Question 30

State the antiviral treatment used in Respiratory Syncytial virus:

Answer 30

Ribavirin (rarely indicated)

Question 31

What are the 2 categories of antiviral resistance that you can get?

Answer 31

Phenotypic & Genotypic

Question 32

Describe phenotypic resistance to antivirals:

Answer 32

• Phenotypic – Virus can grow in presence of compound (HSV)

Question 33

Describe Genotypic resistance to antivirals:

Answer 33

• Genotypic – Sequence genome + identify resistance associated mutations (HIV)

Question 34

When should you suspect resistance to herpes virus in the immunocompromised?

Answer 34

If no response within 7 days

Question 35

If HSV + CMV are both resistant to aciclovir, what is usually effective next?

Answer 35

Foscarnet is usually effective

Question 36

When is HIV resistance testing performed?

Answer 36

At diagnosis/ failing therapy