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Cology 2 Exam 3 > Antiviral 1 - Intro and Herpes viruses > Flashcards

Antiviral 1 - Intro and Herpes viruses Flashcards

1
Q

How big are viruses?

A

Smallest form of life; 20-300 nm

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2
Q

Viruses are classified as ______. This means what? (3 things)

A

Parasites

They are parasites because they:
Rely on host for replication
Are difficult to target; can lead to collateral damage (bc we have to target our own cells to get them)
Encode for few proteins

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3
Q

What proteins do viruses encode?

A

Nucleocapsid
Polymerase
Receptor proteins

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4
Q

What’s the difference between a naked and enveloped virus?

A

Naked viruses consist of capsomers surrounding nucleic acid (icosahedral)

Enveloped viruses are surrounded by glycoproteins, lipid bilayer, and matrix proteins. Inside the cell there is RNA covered by capsid proteins

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5
Q

What problems are there with antiviral therapy?

A

Infections aren’t detected immediately bc immune system not activated by unique components of the virus

Massive proliferation of virus = need for rapid overwhelming intervention (Ebola infection to death is 5 days)

Virus “hijacks” the host cells, which decreases immune response and it’s also hard to distinguish host from pathogen

Rapid viral evolution: High mutation rate of virus, massive numbers of virus particles, mutations occur through jumping species

They are highly infectious

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6
Q

What are the 3 types of viruses?

A 
DNA viruses (double stranded)
RNA viruses (single stranded, + and - types)
Retroviruses (Two copies of RNA)
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7
Q

What are the 2 types of herpes simplex virus?

A

Type 1 - mouth, face, skin, esophagus, or brain

Type 2 - genitals, rectum, hands or meninges

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8
Q

What does Varicella-Zoster cause?

A

Chicken pox

Shingles

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9
Q

What does Cytomegalovirus cause?

A

Retinitis
Esophagitis
Colitis

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10
Q

What does Epstein-Barr cause?

A 
Infectious mononucleosis
Burkitt Lymphoma (Jaw malignancy; first cancer linked to virus)
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11
Q

What was the first cancer linked to a virus? What virus was it?

A

Epstein-Barr virus causes Burkitt lymphoma

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12
Q

What does Herpes Simplex cause?

A

6 and 7 - Roseola

8 - found in 90% of Karposi sarcoma patients

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13
Q

Does Herpes virus cause acute or latent infections?

A

Can be acute or latent

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14
Q

What is HPV Type 1?

A

Cold sores

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15
Q

What is HPV Type 2?

A

Genital herpes

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16
Q

CMV - acute or latent?

A

Acute infections show no symptoms in children

Chronic infections can occur in immune-compromised patients

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17
Q

How is a latent infection established?

A

Virus penetrates into the skin where it replicates, then enters the cutaneous neurons and migrates into the ganglion where it remains in a latent state

Virus can subsequently be reactivated and travel through the sensory neurons to the epidermis

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18
Q

What are guanine analogs?

A

A type of antiviral that inhibits DNA synthesis by entering itself into the DNA, and since they lack a sugar, the next base pair can’t be added so elongation is stopped.

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19
Q

Name the guanine analogs (6)

A 
Acyclovir
Penciclovir
Ganciclovir sodium
Valacyclovir
Famciclovir
Valganciclovir hydrochloride
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20
Q

Why don’t acyclovir/valacyclovir kill us if they inhibit DNA synthesis?

A

They are selectively phosphorylated by viral thymidine kinase and added to viral DNA

21
Q

What are the indications for Acyclovir, Valacyclovir?

A

Herpes simplex

Varicella-zoster

22
Q

Why does resistance occur with Acyclovir, Valacyclovir?

A

Altered thymidine kinase

23
Q

What is the bioavailability of Acyclovir?

A

22% - HSV

24
Q

What is the bioavailability of Valacyclovir?

A

Prodrug with higher bioavailability - 70%

HSV
VZV

25
Q

What are the adverse effects of Acyclovir, Valacyclovir?

A

N/V

Rash

Need to maintain hydration bc renal function (crystallizes in renal tubule)

CNS - seizures, delirium (high conc)

Tremor

Bone marrow suppression

26
Q

Counseling points for Acyclovir and Valacyclovir?

A

Stay hydrated bc they crystallize in renal tubule
Probenacid reduces renal clearance
Give within first 24 hours to shorten acute illness but it doesn’t cure the infection (less intense, shorter duration)

27
Q

Describe penciclovir, famciclovir?

A

Similar mechanism to acyclovir
Used in HSV and VZV
Actions and toxicity similar to acyclovir

28
Q

Bioavailability of Penciclovir?

A

5% - use topically for genital HSV

29
Q

Bioavailability of Famciclovir?

A

Prodrug - 77% - used for Oral HSV, VZV

30
Q

Indications for Ganciclovir, Valganciclovir?

A

CMV in transplant and immuno-compromised patients

31
Q

Bioavailability of Ganciclovir

A

6-9%

Given Oral, IV, Intravitreal (in eye)

32
Q

Bioavailability of Valganciclovir

A

61%

Given orally

33
Q

Adverse effects of Ganciclovir, Valganciclovir?

A

CNS (5-15%) - confusion, ataxia, seizures, coma

Neutropenia (15-40%)

Thrombocytopenia (20-50%)

N, V, Rash

Diarrhea

Increases liver enzymes

34
Q

Which guanine analogs have side effects severe enough that some patients have to stop IV treatment?

A

33% of pts on ganciclovir, valganciclovir have to stop IV treatment because of side effects

35
Q

What is Cidofovir?

A

Cytidine nucleotide that inhibits viral thymidine kinase

36
Q

Why is Cidofovir special?

A

It works in resistant viruses

Doesn’t require viral kinase to become active

37
Q

What are the indications for Cidofovir?

A 
Herpes
CMV
Papilloma
Polyoma
Pox
Adenovirus

CMV retinitis in HIV patients

38
Q

Adverse effects of Cidofovir?

A

Glomerular filtration
Nephrotoxicity
Tubular dysfunction
Neutropenia

39
Q

Bioavailability of Cidofovir?

A

IV only!

40
Q

What is Foscarnet?

A

Pyrophosphate derivative, inhibits viral DNA polymerase

41
Q

Bioavailability for Foscarnet?

A

IV admin only

Adjust dose for renal function!

42
Q

Adverse effects of Foscarnet?

A

It’s nephrotoxic and chelates cations
(Worry about hypocalcemia, hypomagnesemia, and hypokalemia)

Headaches, seizure, fatigue, tremor, hallucinations

Cough, dyspnea, pneumothorax
Fever, rash
Anemia, thrombocytopenia, bleeding!

43
Q

Indications for Foscarnet?

A

CMV retinitis
Acyclovir resistant HSV and shingles
Ganciclovir resistant CMV

44
Q

What is Vidaridine?

A

Purine analog that inhibits viral polymerase

45
Q

What is Vidaridine used for?

A

Ophthalmic solution for HSV and VZV infections

VIDaridine sounds like Visine?

46
Q

Adverse effects of Vidaridine?

A

Irritation
Pain
Photophobia

47
Q

What are Trifluridine/Idoxuridine?

A

Thymidine analogs added into viral DNA by polymerase

48
Q

What are Trifluridine/Idoxuridine used for?

A

Keratoconjunctivities caused by herpes simplex (???)

Ophthalmic ointment only

49
Q

Adverse effects of Trifluridine/Idoxuridine?

A

Burning and itching, mild irritation of the eye

Cology 2 Exam 3 (11 decks)

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