Exam 2: Viral Infections, Antiviral And Antiretroviral Drugs

Question 1

General Principles of Virology: Viral Replication

Answer 1

A virus cannot replicate on its own.

It must attach to and enter a host cell.

It then uses the host cell’s energy to synthesize protein, DNA, and RNA.

Assembly and release of virions (complete, infective form of a virus outside a host cell, with a core of RNA or DNA and a capsid)

Question 2

Why are viruses difficult to kill?

Answer 2

Viruses are difficult to kill because they live inside the cells

Any drug that kills a virus may also kill healthy cells.

Question 3

Viral Illnesses include

Answer 3

Smallpox (poxviruses)
Sore throat
Conjunctivitis (adenoviruses)
Warts
Influenza
Respiratory infections (coronaviruses, rhinoviruses)
Gastroenteritis (rotaviruses, Norwalk-like viruses)
Human immunodeficiency virus (HIV)/ acquired immune deficiency syndrome (AIDS) (retroviruses)
Herpes
Hepatitis

Question 4

Viral Illnesses Treatment

Answer 4

Most viral illnesses are bothersome but survivable

Effective vaccines have prevented some illnesses (i.e. varicella vaccine against chicken pox)

Effective drug therapy is available for a small number of viral infections

Question 5

Antiviral Drugs

Answer 5

• kill or suppress the virus by destroying virions or inhibiting the ability of viruses to replicate
• controlled by current antiviral therapy

Question 6

Immunoglobulins

Answer 6

concentrated antibodies that can attack and destroy viruses

Question 7

IV immunoglobulin (IVIG)

Answer 7

can treat immune deficiencies like immune thrombocytopenia (low platelet count)

Question 8

Medications never fully

Answer 8

eradicate a virus completely from its host

Medications give the body’s immune system a better chance of controlling a viral infection

Question 9

Viruses controlled by current antiviral therapy

Answer 9

Cytomegalovirus (CMV)—cidofovir, foscarnet
Hepatitis viruses—C= simeprevir, sofosbuvir; B=telbivudine, tenofovir
Herpesviruses—acyclovir (Zovirax)
HIV—5 categories—common, zidovudine, tenofovir
Influenza viruses (the “flu”)—amantadine, rimantadine, oseltamivir (Tamiflu)
Respiratory syncytial virus (RSV)—ribavirin

Question 10

Key Characteristics of Antiviral Drugs

Answer 10

Able to enter the cells infected with virus

Interfere with viral nucleic acid synthesis, regulation, or both

Some drugs interfere with ability of virus 
to bind to cells

Some drugs stimulate the body’s immune system

Question 11

Opportunistic Infections

Answer 11

Occur in immunocompromised patients
Would not normally harm an immunocompetent person
Require long-term prophylaxis and antiinfective drug therapy
Can be other viruses, fungi, bacteria, or protozoa

Question 12

Antiviral Drugs (Non-HIV): MOA

Answer 12

Most of the current antiviral drugs work by blocking the activity of a polymerase enzyme that normally stimulates the synthesis of new viral genomes.

Question 13

Antiviral Drugs (Non-HIV): Uses

Answer 13

Used to treat non-HIV viral infections:
Influenza viruses
Herpes simplex virus (HSV)
Varicella zoster virus 
Cytomegalovirus (CMV)
Hepatitis

Question 14

Antiviral Drugs (Non-HIV): Adverse Effects

Answer 14

Vary with each drug

Healthy cells are often killed also, resulting in serious toxicities

Question 15

Antiviral Drugs (Non-HIV): Interactions

Answer 15

Vary with each drug

Question 16

Types of Herpesviridae

Answer 16

1. HSV-1 (oral herpes)
2. HSV-2 (genital herpes)
3. Chickenpox and Shingles (HHV-3 or VZV)
4. Epstein-Barr (HHV-4)
5. Cytomegalovirus or CMV (HHV-5)
6. Human herpesviruses 6 and 7 are not especially clinically significant; immunocompromised patients
7. Kaposi’s Sarcoma (HHV-8)

Question 17

HSV-2

Answer 17

“Neonatal” herpes, often life-threatening
Highly transmissible through close physical contact.
Not Curable

Question 18

HSV-2 Characteristics

Answer 18

Outbreaks of painful skin lesions occur intermittently, with periods of latency.

Question 19

HSV-2 Treatment

Answer 19

Antivirals (acyclovir) can speed up the process of remission and reduce duration of painful lesions
Start medication as early as possible, preferably first 72 hours for best outcomes

Question 20

Varicella (Chickenpox) (HHV-3 or VZV)

Answer 20

Self-limiting
Highly contagious, spread by direct contact with weeping lesions
Varicella virus vaccine recommended for healthy children older than 1 year.

Question 21

Herpes Zoster (Shingles) HHV-3

Answer 21

Painful (opioids for pain control)
Follow nerve tracts (dermatitis): usually unilateral
Postherpetic neuralgias

Question 22

Shingles Treatment

Answer 22

• Acyclovir may speed recovery; best results are generally seen when the antiviral drug is started within 72 hours of symptom onset
• Zostavax: Immunization given in patients 50 years of age and older

Question 23

Antiviral Drugs: Acyclovir (Zovirax)

Answer 23

Synthetic nucleoside analog

Oral, topical (burns upon application), or parenteral forms

Question 24

Antiviral Drugs: Acyclovir (Zovirax): Uses

Answer 24

Used to suppress replication of HSV-1, HSV-2, HSV-3 (VZV)

Drug of choice for treatment of initial and recurrent episodes of these infections

Question 25

Antiviral Drugs (Non-HIV): 
Dose-Limiting Toxicities

Answer 25

Some antivirals at higher doses can cause toxicities the body; therefore they are dose-limited Examples are: Ganciclovir (Cytovene): CMV treatment and bone marrow toxicity Foscarnet and cidofovir (Vistide): CMV in AIDS patients and Renal toxicity

Question 26

Antiviral Drugs (Non-HIV): 
Neuraminidase Inhibitors

Answer 26

Treatment of Influenza Virus

Question 27

Antiviral Drugs (Non-HIV): 
Neuraminidase Inhibitors include

Answer 27

Oseltamivir (Tamiflu) | Zanamivir (Relenza)

Question 28

Antiviral Drugs (Non-HIV): 
Neuraminidase Inhibitors (Oseltamivir and Zanamivir)

Answer 28

Active against influenza types A and B | Reduce duration of illness

Question 29

Antiviral Drugs (Non-HIV): 
Neuraminidase Inhibitors Oseltamivir causes

Answer 29

N/V

Question 30

Antiviral Drugs (Non-HIV): 
Neuraminidase Inhibitors Zanamivir causes

Answer 30

Diarrhea, nausea and sinusitis

Question 31

Antiviral Drugs (Non-HIV): 
Neuraminidase Inhibitors (Oseltamivir and Zanamivir) Treatment should begin

Answer 31

within 2 days of influenza symptom onset.

Question 32

Retrovirus

Answer 32

Type of virus that uses RNA as its genetic material.

Question 33

HIV and AIDS

Answer 33

Retrovirus | Transmitted by sexual activity, intravenous drug use, perinatally from mother to child

Question 34

HIV and AIDS viral factors

Answer 34

Developed virus is easily inactivated and must be transmitted in body fluids Disease has a long incubation period Virus can shed before development of identifiable symptoms

Question 35

Four Stages of HIV Infection

Answer 35

Stage 1: asymptomatic infection Stage 2: early, general symptoms of disease Stage 3: moderate symptoms Stage 4: severe symptoms, often leading to death

Question 36

Antiretroviral Drugs: Highly active antiretroviral therapy (HAART)

Answer 36

Used to treat infections caused by HIV Includes at least three medications These medications work in different ways to reduce the viral load

Question 37

Antiretroviral Drugs include

Answer 37

``` HAART Reverse Transcriptase Inhibitors (RTIs) Protease Inhibitors (PIs) Fusion Inhibitors Entry Inhibitor: CCR5 co-receptor antagonists HIV integrate strand transfer inhibitors ```

Question 38

Antiretroviral Drugs: Adverse Effects

Answer 38

Numerous and vary with each drug Drug therapy may need to be modified because of adverse effects

Question 39

Goal for Antiretroviral Therapy

Answer 39

is to find the regimen that will best control the infection with a tolerable adverse effect profile. Medication regimens change during the course of illness.

Question 40

Antiretroviral Drugs: Zidovudine (Retrovir)

Answer 40

Synthetic nucleoside analogue reverse transcriptase inhibitor First anti-HIV drug

Question 41

Zidovudine (Retrovir) has been replaced d/t

Answer 41

dose-limiting adverse effect of bone marrow suppression | Still used for HIV-infected pregnant women and newborn babies

Question 42

Nevirapine (Viramune)

Answer 42

Nonnucleoside reverse transcriptase inhibitor (NNRTIs) Used in combination with nucleoside reverse transcriptase inhibitors (NRTIs) Well tolerated

Question 43

Nevirapine (Viramune): Common Adverse Effects

Answer 43

rash, fever, nausea, headache, abnormal liver function test results

Question 44

Indinavir (Crixivan)

Answer 44

Protease Inhibitor (PI) Typically given with two nucleoside reverse transcriptase inhibitors (NRTIs) Increased CD4 counts; decreased viral load

Question 45

Indinavir (Crixivan) administration

Answer 45

Best absorbed in acidic gastric environment (do not combine with food) Drink at least 48 oz of water/day.

Question 46

Enfuvirtide (Fuzeon): MOA

Answer 46

Fusion inhibitors Suppresses the fusion process whereby a virion (complete, infective form of a virus) is attached to the outer membrane of a host T cell before entry into the cell and subsequent viral replication

Question 47

Enfuvirtide (Fuzeon): Uses

Answer 47

Used for treatment of HIV infection in combination with other antiretroviral drugs. Use of this drug in combination with other standard antiretroviral drugs: markedly reduced viral loads.

Question 48

Maraviroc (Selzentry)

Answer 48

C-C chemokine receptor type 5 (CCR5) antagonists Selective, slowly reversible, small molecule antagonist of the interaction between the chemokine co-receptor located on the CD4 cells and the virus…blocks this interaction

Question 49

Maraviroc (Selzentry) Uses

Answer 49

Used for resistant strains of HIV-1

Question 50

Maraviroc (Selzentry): Adverse Effects

Answer 50

Hepatotoxicity