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Flashcards in Antiviral Agents Deck (15):


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


Difference between RNA and DNA viruses

RNA viruses are shorter-lasting than DNA viruses
Example: rhinovirus vs. herpes


Infection process of a virus

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



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


Main approach to preventing viral infection

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



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



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


Neuraminidase inhibitors

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


Interferon treatments

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


Nucleoside antimetabolites

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


How HIV works

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)


Reverse transcriptase inhibitors

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


Nonnucleoside reverse transcriptase inhibitors

Treatments for HIV (target reverse transcriptase)
Noncompetitive inhibitors that bind to an allosteric binding site on reverse transcriptase


HIV protease inhibitors

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


Fusion inhibitors

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