3 
C. Biological Containment Criteria Using E. Coli K-12 Host-Vectors 
The commentators were divided on the use of Eh coli , strain K-12 
as host-vectors. There were those who opposed the use of Eh coli 
and others who strongly supported its use. I believe continuation 
of recombinant DNA work in IS. coli is merited. I recognize as well 
the importance of NIH support towards developing alternative host- 
vector systems. 
1&&U.ZA fan, the, ConmotXcz'-i CoYibidoAalxon 
1. EK2 host-vectors: On p. 18 the first sentence cites "data 
from suitable tests performed in the laboratory." In response 
to comments made, would the committee expand on how one tests 
for survival of the cloned DNA fragment? Further, how would 
the committee view our incorporating the following changes in 
the text: "... This absolute measure of biological containment 
has been selected because it is a reallstle measurable entity. 
Indeed, by testing the contributions of preexisting and newly 
introduced genetic properties of vectors and hosts, individually 
or in various combinations, it should be possible to-substantially 
indieata--±f-net-prove , to estimate with considerable precision 
that the specially designed host-vector system can provide a 
margin of biological containment in excess of that required." 
2. EK3 host-vectors: On p. 25 there is a one-paragraph description 
of this system. In light of possibly imminent certification of 
EK2 systems, would the committee consider defining the procedures 
to obtain independent confirmation of the specified containment? 
3. The minutes of your December 4-5, 1975, meeting contain the 
statement that "the Committee passed a resolution that for the 
time being responsibility for certification of putative EK2 
strains and publication of information on which it makes its 
certification lies with the Committee." However, no such state- 
ment appears in the guidelines. How does the committee view my 
inserting into the guidelines a statement that no host-vector is 
to be considered a bona fide EK2 or EK3 until it is certified by 
your committee? 
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