MBIO 2020 Lecture Notes - Lecture 14: Lysozyme, Enantioselective Synthesis, Virus
10 Nov 2016
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Document Summary
A viral enzyme, t4 lysozyme, is synthesized in the late phase of infection. It degrades the host cell peptidoglycan from within, releasing the phages from the host. The average number of virions released by infected cell is the burst size - in this case, 100-300 virions per cell. Cells are infected by dense suspension (108cells/ml) and then diluted x1000. Resulting cell concentration is low such that phage progeny released from infected cells would not find a new host. Virion in medium supernatant are assayed by mixing with host cells and plating on nutrient agar: results are plotted as pfu/ml vs. time. Latent periods - no plaques are formed until the end of late phase infection. Rise period - assembled virions are released from lysed host cell - a sudden increase in pfu. Platue - plague count remains constant because released phages cant find new hosts. This pattern indicates that viruses reproduce by assembly rather than by binal division.
