Antiviral Agents

Question 1

Viruses

Answer 1

Smallest self-replicating organisms
Must replicate in living cells, using the host’s cellular machinery
Can’t conduct metabolic processes on their own
Have either a DNA or RNA genome and a simple protein coat to surround the genome

Question 2

Difference between RNA and DNA viruses

Answer 2

RNA viruses are shorter-lasting than DNA viruses

Example: rhinovirus vs. herpes

Question 3

Infection process of a virus

Answer 3

1. Virus attaches to specific receptors on the cell surface
2. Virus penetrates into the cell (often via endocytosis)
3. Viral nucleic acid is released from protein coat
4. Viral mRNA is produced
5. Viral proteins and nucleic acid are synthesized
6. New viral particles are packaged
7. Mature virus leaves cell through budding or rupture

Question 4

Retroviruses

Answer 4

RNA viruses with reverse transcriptase
Viral cDNA is incorporated into the host genome
Example: human immunodeficiency virus (HIV)

Question 5

Main approach to preventing viral infection

Answer 5

Immunization: giving the body either live or attenuated (protein fragments) virus

Question 6

Chemoprophylaxis

Answer 6

Alternative to immunization
Individuals with functioning immune system: administer an agent that interferes with early viral activity (attachment, entry, uncoating)

Question 7

Amantadines

Answer 7

Only class of chemoprophylaxis that inhibits all 3 stages of early viral activity
Amantadine and Rimantadine: small, rigid structures

Question 8

Neuraminidase inhibitors

Answer 8

Transition-state analogs that mimic neuraminidase’s (enzyme critical for viral entry into a cell) natural ligand, sialic acid
Example: Zanamivir

Question 9

Interferon treatments

Answer 9

Cytokines (cell communication molecules) that inhibit viral protein synthesis by stimulating natural killer cells to destroy infected cells and inducing an antiviral state in neighboring cells

Question 10

Nucleoside antimetabolites

Answer 10

Inhibit viral nucleic acid production (resemble nucleic acids and halt viral DNA/RNA reproduction)

Question 11

How HIV works

Answer 11

HIV infects many cell types in the human immune system
Low T-helper cell counts lead to loss of cell-mediated immunity
Infected individuals become more susceptible to opportunistic infections, leading to the onset of acquired immune deficiency syndrome (AIDS)

Question 12

Reverse transcriptase inhibitors

Answer 12

Treatments for HIV (target reverse transcriptase)
2,3-dideoxynucleoside analogs
Examples: Zidovudine, Didanosine, Satuvidine

Question 13

Nonnucleoside reverse transcriptase inhibitors

Answer 13

Treatments for HIV (target reverse transcriptase)

Noncompetitive inhibitors that bind to an allosteric binding site on reverse transcriptase

Question 14

HIV protease inhibitors

Answer 14

HIV protease cleaves viral polypeptides to form active enzymes required for the HIV replication cycle
Inhibitors are transition state analogs that mimic the tetrahedral transition state of an amide undergoing hydrolysis

Question 15

Fusion inhibitors

Answer 15

Treatments for HIV

Prevent glycoprotein gp41 from participating in membrane fusion events, thus preventing HIV entry