plaque assay
Title: Exercise Seven - Plaque Assay for Determination of Phage TitreOne of the most numerous microorganisms known to man is viruses and theseacellular agents can infect all types of cellular organisms. Viruses are consideredinfectious elements that contain a single type of nucleic acid but require a host cell'smetabolism to replicate. They are typified by both an extracellular state and anintracellular state. (Madigan et al, 2003; Prescott et al, 2002).The classification of viruses can be extended further, by focusing on a specificgroup known as Bacteriophages. These are viruses that infect bacterial cells and use themas their host. Those viruses that infect Eschericha coli are known as Coliphages and areidentified by type numbers ie. T2, T4 and T7. (Prescott et al, 2002; Reddy, 2002).Temperate bacteriophages not only infect bacteria but can also establish alysogenic relationship rather than immediately lysing their hosts. The DNA
Thus by obtaining the number ofplaques present on a culture, the volume plated and the dilution factor, it is possible toquantify the original virus suspension. Further evidence of viral growth in cultured cells can be found by observingcytopathic effects. Aim:The main aim of this experiment was to determine the titre of a bacteriophagepreparation using the plaque-forming technique. Materials:As per the 2003 MIC2022 Practical Manual, pp. These results from the release of virusparticles from the host cell after all stages of the lifecycle are complete. The number of virions released is called the burst size, and this can vary between viruses. of theinvading phage has two possible fates: reproduction leading to generation of new phageparticles and lysis of the cell or integration into the host chromosome. Excluding the lysogenic pathway for the moment, a typical virallifecycle can be categorized into five stages:1. The time it takes for a virus to complete its lifecycle can be measured by the onestepgrowth (multiplication) curve. Synthesis of nucleic acid and proteins: where the host's metabolism is utilized4. This occurs in the first fewminutes after infection when the virion is no longer considered an infectious entity.
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