FEBRUARY 15-16 - MINUTES OF MEETING 
22 
XV. USE OF Ff BACTERIOPHAGES FOR EK1 CONTAINMENT . 
Dr. Campbell discussed a proposal (Attachment II) to permit use of Ff 
bacteriophages as EK1 vectors. He summarized the report of the Phage 
Subcommittee on the use of Ff phages as EKl vectors. 
Dr. Campbell summarized the biology of these single-stranded phages. 
Normally, the phages can infect only F + cells as the male pili are 
the attachment site for this virus. However, the Guidelines pro- 
hibit cloning in F 4- cells. He pointed out that there are two methods 
to grow phage without the F 4 factor. The first involves the use of 
phage DNA to infect cells. [NIH has already approved this procedure] . 
The second method involves the use of certain F mutants that make 
pili but are unable to transfer DNA by conjugation. In the latter 
cells, phage can grow in the normal manner. The Subcommittee con- 
cluded that the Ff phages are as well contained as A in the 
absence of the F factor. The Subcommittee recommended that NIH approve 
the use of Ff phages with conjugation deficient mutants of the F factor. 
They further recommended that at the next meeting the RAC consider 
amending the Guidelines to permit use of F 4 hosts. 
Dr. Zinder described the utility of Ff phages. The complete nucleotide 
sequences is known, and DNA can be inserted by a variety of techniques. 
Also, the phage is not limited in size. As soon as F + cells become 
infected, they lose their sexuality. The pili are withdrawn and F + is 
no longer expressed. He stated that it requires great care to grow 
infected cells. The phage is not common and the attachment rate for 
phage to a host is 2 orders of magnitude lower than for A . Seme 
members of the RAC felt that since A is an approved vector, the 
Ff phages should be approved. Dr. Campbell stated that the concerns 
expressed by the European Science Foundation's Liaison Committee on 
Recombinant DNA Research had been taken into consideration by the 
Subcommittee. 
Dr. Campbell moved that the RAC recommend that ORDA authorize the use 
of the male-specific bacteriophages in conjugation-deficient strains 
for EKl containment as follows: 
Conjugation deficient mutants, such as the traD and tra l 
mutants of the F factor, may be used with Ff bacteriophages 
if the mutants have been shown to exhibit low levels of 
transfer (of the order of 10 “ 5 or less) and also have low 
reversion rates (such as found for deletion or double 
mutants ) . 
[ 68 ] 
