43 
Slide 5 
£ coli Bacteriophage as Vectors 
bacteriophage 
production lysogen 
plasmid 
The DNA and the protein can be replicated in the cell forming new viral 
particles, and the cell can open and release those particles. Alternatively, 
the DNA of the bacteriophage can become an integral part of the chomosomal 
DNA of the bacteria, a process called lysogen formation. Or the bacterio- 
phage DNA can establish itself as a plasmid within the bacterial cell. 
Therefore, in discussing biological containment for systems using bacterio- 
phage DNA as a vector, these three possible modes of escape and perpetuation 
of a recombinant bacteriophage DNA must be considered. 
The next slide (6) summarizes current estimates for containment of such 
systems as described in the guidelines. The estimates are made for a par- 
ticular bacteriophage of coli , which is called lambda, since this widely 
studied bacteriophage is most likely to be used for recombinant experiments 
at the present time. 
Considering first information relevant to escape of the bacteriophage 
particle, lambda is sensitive to the acidity of the stomach and is likely to 
be destroyed there. Normal intestinal strains of E_j_ coli are usually not 
susceptible to infection by lambda, and in fact, susceptible strains are 
rare in nature. Further, in at least one case, ingestion of 10^ lambda 
particles yielded no detectable lambda in resulting feces. 
Lambda bacteriophage are also readily destroyed by drying, as might 
happen if the particles got into the air. 
[184] 
