Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
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.
|
1.Attachment
2.Penetration 3.Uncoating 4.Synthesis phase 5.Maturation 6.Release |
|
|
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?
|
Interferons.
|
|
|
What is the mechanism of action of Relenza?
|
It is an analog of sialic acid which is the essential component of the viral receptor.
|
