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17 Cards in this Set
- Front
- Back
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Infectious agent that passes through filters, so small that it will pass through any filter
From 20nm to 300 nm |
Virion
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Are small size and obligatory intracellular growth things an absolute definitions of virus?
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No, there are other things that share these traits
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Obligatory Intracellular Growth
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Virion outside of cell cannot multiply
Can only multiply inside host cells in order to produce many progeny virions |
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What defines a virus? (there are 4 - 2 airtight and 2 not)
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1) How it replicates - construct individual components of virion (proteins, genetic info) and then parts assembled SPONTANEOUSLY
2) viruses only contain one type of genetic info - RNA or DNA (not both) - single or double stranded 3) small size 4) obligatory intracellular growth but these two are not airtight definitions |
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Are all viral genes components of virion?
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No some just play a role in the replication and assembly of virion
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How many genes does a virus have to control the synthesis of its DNA or RNA?
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one
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What is Neutralization?
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specific way to identify viruses - have antibody that binds to virion and neutralizes it (cannot infect cell and cannot multiply)
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If you take virus solution and put it into in vitro cell culture, you will get mov't of epidemic from cell to cell. You get zone of clearing where virus has killed cells = plaque forming unit representing one infectious virion infecting cell at center of dead zone. What is this assay called and how does it help you figure out the number of infectious virions?
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This is called cytopathic effect of cells. This helps measure INFECTIOUS virions in a suspected solution, by counting plaque forming units.
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What assay tells you the number of INFECTIOUS virions?
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A plaque assay
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What are two types of inclusion bodies that can be clues to the nature of the virus?
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Cytoplasmic or nuclear inclusion bodies
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How do you detect neutralization by antibodies?
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Embryonic eggs, tissue culture, infect animals (rare)
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What is another way to diagnose viruses rapidly and specifically by looking at the genetic material?
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PCR - replicate info in virions, because viruses have specific nucleotide sequences
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If patient in office showing symptoms do they have immune response yet?
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No this takes a while to happen - in this acute symptomatic phase you can't do anything for the patient,
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How do you use a patient in your office to figure out what virus the patient has?
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When sick patient comes in take an acute serum sample. Then have them come back in month because they will have antibodies (take convalescent serum sample with immune response mounted), so when you can mix acute and convalescent serum samples with different viruses you see which virus is neutralized by convalescent serum and not the acute serum -->tells you virus
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Hepatitis and HIV Infections - production of antibody is delayed, what significance does this have and what is it called?
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Window period, problem for blood banking
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Is there any lipid in a nucleocapsid?
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No it is all protein!
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Is there any lipid in a nucleocapsid?
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No it is all protein!
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