Virus Watch: Counting Viruses
In this episode of Virus Watch, I show how to do my favorite assay in all of virology – the plaque assay.
pfu
Are all virus particles infectious?
Chris Upton, a contributor to the virology toolbox, has raised an important point about multiplicity of infection: Perhaps this is a place to bring up particle to pfu ratio? The above is great for when talking about phage, for example, when the ratio approaches 1. But with something like polio when it can be very …
How many viruses are needed to form a plaque?
The plaque assay is an essential tool for determining virus titers. The concept is simple: virus infection is restricted to neighboring cells by a semisolid overlay. By counting the number of plaques, the virus titer can be calculated in PFU per ml. A key question is: how many viruses are needed to form a single …
Detecting viruses: the plaque assay
One of the most important procedures in virology is measuring the virus titer – the concentration of viruses in a sample. A widely used approach for determining the quantity of infectious virus is the plaque assay. This technique was first developed to calculate the titers of bacteriophage stocks. Renato Dulbecco modified this procedure in 1952 …