Antiviral Medication Flashcards
What are viruses?
Obligate intracellular parasites; they rely on host biosynthetic pathways to reproduce.
What are virions?
Independent virus particles that exist outside of infected cells.
What do virions consist of? (3)
Double or single stranded RNA.
Protein coat.
Lipid envelope.
What s a capsid?
Protein coat of a virion.
What is the lipid envelope? Where is it derived from?
Envelope derived from host cell which contains antigenic glycoproteins.
What is viral range?
The group of cell-types/species a virus can infect.
What is a bacteriophage?
A virus that only infects bacteria.
What are viruses that only infect animals or plants referred to?
Animal viruses or plant viruses.
Most viruses do not cross ____, and some only infect closely related ______.
Phyla, species.
What are the three shapes of capsids?
Helical, icosahedral, complex.
How are viruses classified?
Based on the capsid shape.
What is pathogenicity?
The ability of a virus to cause disease.
What is virulence?
The degree of pathogenicity.
What is latency?
The phenomenon in which viruses remain dormant in organisms.
What is an example of latency in humans?
Chicken pox; latency in spinal cord is reactivated as shingles in adulthood.
What are carriers?
People chronically infected with a virus that serves as reservoirs of infectious viruses.
What is the life cycle of viral replication?
Absorption, penetration, replication, release.
What determines the host range of a virus?
Interaction between host cell receptors and glycoproteins on virus surfaces.
What cell receptors do the proteins on HIV interact with?
gp120 (CD4) CCR5 (T)
After the virus binds with cell surface receptors, what are the following processes of infection?
The virus is fused with the membrane, crossing is and releasing viral RNA/DNA that crosses into the nucleus to impact transcription (reproduce itself)
Where does a virus utilize host machinery for transcription?
Nucleus.
Where does a virus utilize host machinery for translation?
Cytoplasm.
Where do newly synthesized virion particles move after translation?
They are released by the cell to continue the infection cycle.
What are the two formes of nucleic acids in viruses?
ss or ds RNA/DNA
How do DNA viruses typically infect a cell?
- Enter the host nucleus and integrate into the genome (because they are DNA).
- Transcibed by host DNA-dependent RNA polymerase, then translated into virus-specific proteins in cytoplasm.
What do DNA viruses require in the cell for replication?
DNA-dependent DNA polymerase.
What kind of virus required DNA-dependent DNA polymerase for replication?
DNA virus.
What kind of virus requires DNA-dependent RNA polymerase for transcription?
DNA Virus
What is the exception of DNA viruses and host machinery?
Poxiviruses carry their own DNA-dependent RNA polymerase and replicate in the host cell cytoplasm.
What do RNA viruses require for transcription?
RNA-dependent RNA polymerase.
What polymerase acts both as a transcriptase and replicase for viruses?
RNA-dependent RNA polymerase.
Where do RNA viruses complete replication?
Cytoplasm.
Which RNA virus completed replication in the host cell nucleus?
Influenza.
What are retroviruses?
Viruses with RNA genome that direct the formation of a DNA molecule in the host cell.
What enzyme copies viral RNA into DNA?
Reverse transcriptase.
What is the function of RNA-dependent DNA polymerase?
To translate RNA into DNA molecules.
What three enzymes are required by retroviruses for infection of the host cell?
- Reverse transcriptase to turn into ssDNA.
- RNA-dependent DNA polymerase to turn into dsDNA.
- DNA-dependent RNA polymerase to copy DNA strand or form mRNA.
What is the cheapest and most effective way of preventing infections by viruses?
Vaccinations.
What are the four categories of vaccines?
Live attenuated
Inactivated (killed antigen)
Subunit (purified antigen/mrna)
Toxoid (inactivated toxins)
What steps of the viral replication process do anti-virals block?
- Viral entry into cell.
- Nucleic acid synthesis.
- Protein synthesis.
- Viral packaging.
- Virion release.
What can combination therapy prevent or delay the emergence of?
Anti-viral resistance
What is virustatic? Which class of drugs is classified as this?
When a drug is only active against replicating viruses and do not affect latent viruses.
What does the administration of acyclovir result in?
DNA chain termination in viral replication due to lacking hydroxyl group important for elongation.
What anti-viral is acyclovir classified as?
Anti-herpes drug.
What is required of acyclovir in order to be incorporated into viral DNA? What enzyme catalyzes this reaction?
Phosphorylation to acyclovir-triphosphate.
ENZYME: thymidine kinase.
What is the affinity of thymidine kinase for acyclovir compared to mammalian kinase?
200X greater
What causes acyclovir resistance in HPV?
- Impaired production of viral thymidine kinase.
- Altered thymidine kinase substrate specificity.
- Altered DNA polymerase.
What is a lentivirus?
A family of retroviruses that lead to chronic persistent infection with gradual onset of clinical symptoms.
What is an example of a lentivirus?
HIV
What cells does HIV infect? What does this result in?
CD4+ T cells; cause to decline to critical levels and lose cell mediated immunity. Body becomes susceptible to opportunistic infections.
What viral infection sites do anti-viral HIV drugs target?
- Fusion.
- Transcription.
- Integration.
- Release
What are entry inhibitors?
Anti-viral drugs that interfere with binding, fusion, and entry of an HIV virion into a cell.
What is integrase?
Viral enzyme that inserts viral genome into DNA of host cell.
What is aspartate protease?
Viral enzyme that cleaves precursor proteins to form the final structural proteins of the mature virion core.
What are protease inhibitors typically used in combination with?
Reverse transcriptase inhibitors.
What is the M2 protein?
A protein that functions as a proton ion channel required at the onset of infection to permit acidification of the virus core, which in turn activates viral RNA transcriptase.
What strain of influenza does amantadine work against?
A.
What are neuroaminidases?
Enzymes that cleave sialic acid residues from viral proteins that enables virion release.
