ABSTRACT
The relationship of plasmids, viruses, and bacterial hosts is an intimate one and frequently constitutes a cyclic event. For instance, one cultures Escherichia coli bacilli to obtain the plasmids contained in the cell, then removes these plasmids and uses them as a vector to convert them into a recombinant structure, and finally reintroduces the new plasmid back into E. coli bacteria as the microbial host for cloning. When a viral phage is used, the procedure is slightly different, in that the viral DNA or RNA is isolated, recombinantly modified, and then inserted into a bacterial host for cloning.
