Attachment II, Page 1 
Sunmary of Conference Call on Pressed EK2 HOst-\fector Systans 
Submitted by Dr. Roy Curtiss dated September 25, 1981 
January 21, 1982 
Drs. Campbell, Clewell, Friedman, Goldstein, Gottesman, Levine, Maas, and 
Gartland met by conference call on January 21, 1982, to discuss the submission 
of Dr. Roy Curtiss dated September 25, 1981. 
Request 1 deals with use of su+ and su“ derivatives of EP50 with previously 
approved virulent lambda vectors. It was noted that most of the contaiment 
in these systems is provided by the lambda vector and that testing data have 
been provided for Charon 4A. Although the testing data are for a period of 8 
hours rather than 24 hours, it was felt that the strains look at least as 
good as IX>50. With regard to survival in rats following oral administration 
(Table 5, page 166) , it was noted that only vitro data are required for 
testing at the YK2 level. It was the consensus of the consultants that the 
strains in part 1 of the request be ^proved for use with those lambda vectors 
certified for use in DP50 on the condition that the su" strain not be used as 
a propagation host. 
The participants then reviewed parts 2 and 3 of the request. It was noted 
that these proposals include requests for use of virulent and temperate 
lambda vectors, as vrell as cosmids. It was agreed that with regard to the 
temperate phages and cosmids, additional data are needed on how the phages 
are constructed, how they behave in the host, how they persist, etc. Ihe 
participants requested the information provided by Dr. Pierre Tiollais on 
the construction and properties of the temperate lambda vectors, and information 
provided by Dr. Jcbn Collins on the construction and properties of the cosmid 
vectors. They also requested a copy of "Section 4" of a r^x>rt referred to 
by Dr. Curtiss and information on certification of cosmid vectors (These 
documents were mailed to the participants on January 26). Dr. Levine sug- 
gested that testing in humans should be done. Again it was pointed out that 
EK2 certification has never required vivo besting . 
The group was divided on how to handle parts 2 and 3 of the submission. Four 
participants (Drs. Campbell, Qewell, Friedman, and Maas) recemmended that the 
strains in parts 2 and 3 be approved for use with plasmids certified for use 
in 1776 and for use with virulent fbages on the condition that su“ strains 
not be used as propagation hosts. Dr. Gottesman said that she would prefer 
to vote only on the phage vectors. Dr. Goldstein abstained. Dr. Levine 
abstained on the basis that he does not agree with the criteria for EK2 
systems. It was agreed that further consideration is needed on the request 
for use of temperate phages and cosmids with these hosts. 
[ 366 ] 
