23 
that virulent lantxia vectors cxxitaining certain mutations will not 
persist in the envirorment; the survivability of the host in the environ- 
ment is then a less important consideration. For this reason virulent 
lambda vectors can be certified without too much data on host 
survivability being evaluated. 
With the plasmid r cosmid and lambda lysogen vectors, viiether the host 
establishes in the environment is a more important consideration. Hie 
data D:. Curtiss supplied on survival for the proposed host strains are 
less than were evaluated for the EK2 approved host x 1776. Furthermore, 
Dr. Curtiss does not provide enough data on the proposed cosmid and 
lambda lysogen vectors. These portions of the proposal should be rejected 
as supporting data are lacking. Dr. Gottesman suggested that for cer- 
tain plasmids, the available data may be adequate to warrant approval. 
Hie ^starts using virulent lambda vectors should perhaps be certified. 
Dr. Friedman said the ^ hoc working group did not recommend ^proval 
of those sections of the proposal dealing with lysogenizing phage vectors, 
plasmid, and cosmid vectors. He recommended approval of strains xl984, 
X 2705, x2001, and x2363 vhen virulent lambda jhages are used as vectors. 
Dr. Friedman asked if the RAC had specified criteria for certification 
of lysogenizing lambda. Dr. Gottesman replied that they have not; no 
previous submissions dealing with lysogenizing phages were received. 
She thought the testing criteria for cosmids might be ^plicable to 
lysogenizing phages. 
Dr. Levine expressed his concern ever the testing criteria specified 
for EK2 certificaticxi. He noted that at the time the EK2 criteria 
were designed, no data on xl776 survivability in man were available. 
When those data became available, it was discovered that xl776, con- 
taining pBR322, survived longer in man than xl776 without pBR322. 
E&ta generated from the mouse system did not predict this phenomenon. 
He suggested that another level of testing be added to the EK2 criteria; 
feeding experiments in man should be performed, as these yield the 
most pertinent data. 
Dr. Talbot suggested that ary redefinition of EK2 criteria should be 
considered by the EK2 working group vAiich could report at the next 
RAC meeting . At this meetirg , RAC should use current criteria to 
evaluate Dr. Curtiss' proposal. Mr. Thornton concurred. Dr. Levine 
suggested that a motion bo defer consideration of parts two and three 
of Et. Curtiss' proposal might be in order. 
Dr. Ahmed asked if the EK2 certification criteria would be changed by 
the reconmendation on revising the Guidelines made earlier in the 
meeting (Item IV abeve). Drs. Talbot and Gottesman replied ^at it 
would not. Dr. Martin asked if xl776 would fall under a graridfather 
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