(Final) Virus purification & Quantification

Question 1

What machinery is used to efficiently sediment even the smallest viruses?

Answer 1

Ultracentrifuge

*used for concentration and purification

Question 2

Rate zonal centrifugation will separate viruses based on what?

Answer 2

Their mass

Question 3

Isopycnic centrifugation separates viruses based upon what?

Answer 3

Their density

Aka buoyant or equilibrium separation

Question 4

What method is used for virus purification?

Answer 4

Membrane chromatography

Question 5

What is virus quantification?

Answer 5

Counts the number of the viruses in a specific volume to determine the concentration

Question 6

What is the virus titer?

Answer 6

is the minimum concentration of virus in a given volume of solution that will still infect cells

number of infectious units per ml of sample

Question 7

What are the two basic types of viral quantification tests?

Answer 7

Biological and physical

Question 8

Direct particle counts by transmission electron microscopy is an example of what kind of quantification test?

Answer 8

PHYSICAL

direct counting of viral particles in solution

Question 9

Using the virus counter 2100 is an example of what kind of quantification test?

Answer 9

PHYSICAL

direct counting of viral particles in solution

Question 10

Hemagglutination assay measures what? What kind of quantification test is this?

Answer 10

Quantification assessment based on antigen concentration
(hemagglutination titer)

This is a physical test

Question 11

Single Radial Immunodiffusion (SRID) is an example of what kind of quantification test?

Answer 11

Physical test

Radial diffusion of purified viral antigens (standards) and viral particles through agarose gel seeded with polyclonal antiserum against the viral antigen

Question 12

T/F: Quantitative PCR is considered a physical quantification test

Answer 12

TRUE

assessment based on gene expression

Question 13

Biological assays that assess viral quantification include what tests?

Answer 13

Monolayer Plaque Assay

Pock assay

Various endpoint titration methods

Question 14

What is the unit used to express virus concentration when using the Monolayer plaque assay technique?

Answer 14

Plaque-forming units/ml = PFU

the number of virus particles capable of forming plaques per unit volume.

Ex: a solution has a PFU of 1000 pfu/ml; then every ml of solution contains enough viruses to make 1000 plaques

Question 15

What unit is used when performing a pock assay?

Answer 15

Pock forming units/ml

Pock = necrotic area on the CAM of embryonated egg

Question 16

What test results in quantitative determination of titers of oncogenic viruses?

Answer 16

Transformation assay

Unit: Focus-forming units/ml

Question 17

T/F: Quantal assays are a biological quantitative test

Answer 17

True

Results in the ENDPOINT = virus dilution that affects 50% of test subjects

Question 18

What is the TCID50?

Answer 18

The tissue culture infectious dose which will infect 50% of the cell monolayers challenged with the defined inoculum