Questions

· d’Herelle and Sinclair Lewis, the author, proposed the use of phage-therapy for human disease, but the procedure was not successful in their hands. List two reasons why the use of phage might not be reliable to wipe out active pathogens in your body.

· Why are phage a hazard in commercial fermentations of cottage cheese, acetone/butanol, tetracycline, etc.?

· List 5 diseases where the pathogenic bacteria uses phage encoded genes for production of the toxin that is responsible for the pathology of the disease. What is the difference between virulent and temperate phage?

· The 5 steps in the life cycle of phage infection:

· Two groups of phage that do not always lyse the host cell.

· Two phages: one phage yields small clear plaques, the other phage yields large turbid plaques – what phages were used to make these plaques?

· What is the burst size of most phages discussed in class? And what are the consequences?

· How long is the life cycle of typical phages discussed in class?

· Outline the procedure for isolating a phage from nature:

a) where do you find phage in nature?

b) how to enrich? – two steps

c) how to harvest mixed phage?

d) how to enrich for one phage?

· How to make a “crop” of a pure phage? – two ways, and what are the yields expected.

· What is MOI and who cares? And what is the result on numbers of progeny if a high MOI is used?

· Describe virus in each group: (MS2, fr, f2), (fX174), (M13, Fd, F1), (T-evens, P1), (T-odds.)

· What do phage need to adsorb to hosts: ions, sometimes nutrients, phage adsorption structures, cell wall receptor site.

· How to isolate phage resistant cells, how to identify those that are unable to adsorb, and why is this important?