Plaque Assay Techniques and Calculations

The video tutorial explains the concept of virus titer and the plaque assay method used to measure it. The plaque assay involves preparing serial dilutions of virus stocks, inoculating them into cell monolayers, and using a medium to restrict virus spread. Plaques form as visible zones of infected cells, which are counted to calculate the virus titer in PFU per mL. An example calculation is provided to illustrate the process. The video concludes with a call to action for viewers to like and share the content.

What is the primary focus of this video?

• The history of virology

• The importance of virus titer

• The lifecycle of bacteriophages

• The structure of viruses

Who modified the plaque assay technique for animal biology?

• Robert Koch

• Renato de Balker

• Alexander Fleming

• Louis Pasteur

What is the first step in performing a plaque assay?

• Counting plaques

• Preparing tenfold serial dilutions

• Staining the cells

• Incubating the plates

What restricts the spread of new virus to neighboring cells in a plaque assay?

• The type of virus

• The nutrient medium

• The incubation temperature

• The gel or medium used

What is used to enhance the contrast between living cells and plaques?

• Dyes

• A microscope

• A camera

• A magnifying glass

What is the unit of measurement for virus titer in a plaque assay?

• Viruses per cell

• Cells per milliliter

• Milliliters per plaque

• Plaque forming units per milliliter

Why are plates counted in duplicate during a plaque assay?

• To increase the number of plaques

• To save time

• To enhance accuracy

• To use more resources

In the example calculation, what is the dilution factor used?

• 10^10

• 10^8

• 10^6

• 10^4

How many plaques were counted in the example calculation?

• 200

• 100

• 150

• 180

What is the final titer of the phase stock in the example calculation?

• 1.8 x 10^11 pfu/ml

• 1.8 x 10^9 pfu/ml

• 1.8 x 10^12 pfu/ml

• 1.8 x 10^10 pfu/ml