Introduction In virology, a quantitative assay is a method used to measure the number of virus particles in an inoculated substance. There are various types of quantitative viral assays such as a plaque assay, infectious center assay, pock assay, and transformation assay. All of these assays contain different characteristics and are used to quantify different viral properties.
In this lab, the quantitative assay that was constructed was a plaque assay. A plaque assay is a modification of a bacteriophage assay and is used to estimate the titer (concentration of a solution) of a phage stock. A plaque assay contains a virus combined with bacterial cells on the surface of an agar plate. The agar plate inhibits the spread of viral progeny to neighboring bacterial cells which results in plaque formation (lysis of bacterial cell). The purpose of this lab was to perform a bacteriophage assay and to calculate the original stock titer of the phage stock using the known set of dilutions and direct plaque count. The hypothesis for this experiment was that plaques will form on all the agar plates within a range count of 30 to 300.
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The formation of plaques did occur on each agar plate, however the number of plaques could not be determined due to the excessive plaque formation in figures 1 and 2. Thus the titer of phage stock could not be determined for the agar plates in figure 1 and 2. However, the number plaque formation could be determined in figures 3 and 4. In addition, the results from figures 3 and 4 were expected and it appeared that figure 3 had a higher plaque count than figure 4. Thus, the agar plates in figure 3 had a higher titer of phage stock than the agar plates in figure