#1
What is the main purpose of viral plaque assays?
To measure the concentration of viruses in a sample
ExplanationQuantify virus concentration.
#2
What does a plaque represent in a viral plaque assay?
A clear zone of lysed cells
ExplanationClear zone indicates cell lysis.
#3
What is the principle behind the formation of plaques in a monolayer of cells?
Viral lytic cycle
ExplanationPlaques form due to viral lytic cycle.
#4
Which statement best describes a 'pfu' in the context of viral quantification?
Plaque forming unit, indicating the number of virus particles capable of forming plaques
Explanation'pfu' is a unit representing virus particles forming plaques.
#5
Why is it important to achieve a uniform monolayer of host cells in a plaque assay?
To ensure equal exposure of all cells to the virus
ExplanationUniform monolayer ensures equal virus exposure to all cells.
#6
Which of the following is NOT a component of the medium used in plaque assays?
Viruses
ExplanationExcluded component in assay medium.
#7
How is the titer of a viral sample calculated using a plaque assay?
By counting the number of plaques and adjusting for dilution factors
ExplanationTiter calculation involves plaque counting and dilution factor adjustment.
#8
Which type of cells are commonly used for viral plaque assays?
Animal cells
ExplanationAnimal cells are common hosts in plaque assays.
#9
Why are overlays used in viral plaque assays?
To restrict the spread of viruses to a two-dimensional plane
ExplanationOverlays confine virus spread to a 2D plane.
#10
What role does the incubation period play in viral plaque assays?
It allows sufficient time for viral replication and plaque formation
ExplanationIncubation period enables replication and plaque formation.
#11
In the context of viral plaque assays, what is the purpose of staining the cell layer?
To increase the contrast between plaques and the uninfected cell layer
ExplanationStaining enhances contrast for plaque visualization.
#12
What is the significance of using a serial dilution in viral plaque assays?
To obtain a countable number of plaques
ExplanationSerial dilution ensures a quantifiable plaque count.
#13
How does the presence of a viral envelope affect plaque assays?
Enveloped viruses require special additives to form plaques
ExplanationEnveloped viruses need additives for plaque formation.
#14
Which factor does NOT influence the size and clarity of plaques in viral plaque assays?
The color of the medium
ExplanationMedium color does not affect plaque characteristics.
#15
What impact does the multiplicity of infection (MOI) have on plaque assay results?
Higher MOI leads to smaller plaques due to limited host cell availability
ExplanationHigher MOI results in smaller plaques due to limited host cells.
#16
How do antiviral compounds affect viral plaque assays?
They can reduce the number or size of plaques, indicating antiviral activity
ExplanationAntivirals reduce plaque count or size, indicating activity.
#17
Which factor is NOT typically varied to optimize plaque assay conditions?
The type of lighting used during incubation
ExplanationLighting type is not a variable in plaque assay optimization.