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19 Cards in this Set

  • Front
  • Back
What are the two stages of the virus life cycle? During which one does replication occur?
*extracellular and intracellular
*replication occurs during the intracellular stage
What are the two stages of the virus life cycle? During which one does replication occur?
*extracellular and intracellular
*replication occurs during the intracellular stage
What is the eclipse period?
The time from the initial infection of the cell until the intracellular assembly of virions begins. The virus is virtually undetectabel within the cell during this time.
What is the latent period?
The time from the initial infection of the host cell until the first infectious virions are released. The virus is virtually undetectable in the blood during this stage.
What is the "burst size"?
The nnumber of progeny virions released from a single infected cell.
What is the multiplicity of infection?
The number of infectious virions per cell at the outset of the infection. High (10-100 virions/cell) means that all sensitive cells have been infected. Low (0.1 virions per cell) means that each cel may have as few as 1 virion at the outse of infection.
What are the early and late synthesis phases seen in DNA viruses?
*early phase is prior to viral DNA synthesis and is for synthesis of viral enzymes and regulatory proteins
*late phase begins with the synthesis of viral DNA and includes synthesis of structural proteins
List the 6 steps in viral infection of individual cells.
4.Synthesis phase
How do viruses achieve attachment to host cells? How does this mediate the presentation of the infection?
Exterior domains on the virus interact with host cell receptors - this leads to tropism to those host tissues which express the specific receptors.
What are three ways that viruses penetrate host cells?
1.Receptor-mediated endocytosis
2.Pore formation
3.Membrane fusion (enveloped viruses)
Besides penetration of the host cell, what can a virus that expresses an active fusogenic protein facilitate?
This protein can cause infected cells to fuse with adjacent cells to allow cell-to-cell spread of the virus and formation of giant multinucleate cells.
How does an inactive or cryptic fusogenic protein work?
The protein is activated after the virus has been taken up by receptor-mediated endocytosis and allows the virus to fuse with the endosome to enter the cytoplasm.
How do progeny genomes and capsids form functional virions inside the infected cell?
They associate by a process of self-assemblly mediated by non-covalent protein-protein and protein-genome interactions.
What virus do amantadine and rimantadine work against and what is their mechanism of action?
*effective against influenza A
*block the M2 channel protein to prevent release of the nucleocapsid from the endosome to the cytoplasm
How do "chain terminators" work? Give three examples.
*these are nucleoside/tide analogs that are taken up during viral DNA synthesis and block further synthesis...most must be phosphorylated before they are takien up by the cell
*AZT, ganciclovir, acyclovir, lamivudine
What is Foscarnet?
A pyrophosphate analog that inhibits the synthesis of the viral genome.
How does Neviparine work?
It binds directly to HIV RT and inhibits the DNA polymerase activity.
What semi-endogenous substances are used for antiviral therapy?
What is the mechanism of action of Relenza?
It is an analog of sialic acid which is the essential component of the viral receptor.