25 
Dr. Clowes said at the February 6 FAC meeting he had supported the motion 
to lower containment requirements to P2 because: (1) coli and Shigella 
exchange genetic information in nature, and (2) other virulence factors 
in addition to toxin production are necessary for pathogenicity. He said 
he had abstained during the vote, however, because he felt the language of 
the motion was vague. Dr. Clcwes said he supported the current recommend- 
ations of the Working Group on Toxins. However, as E. coli K-12 probably 
possesses a chromosomal Shiga toxin gene, he would like to suggest that 
the working group recanrmendation on item three of Dr. O'Brien’s April 4 
request be modified to require P2 containment conditions. 
Dr. Fedor off felt P2 containment was not necessary. She pointed out that 
two recambi national events would have to occur to generate a plasmid vector 
carrying the full structural gene for Shiga toxin: one reccmbinational 
event to integrate the plasmid into the chrcmoscme, and a second to 
return the plasmid to the extra chrcmoscmal state. 
Dr. McKinney said Dr. Cl ewes' suggestion satisfied Dr. Holmes' concern 
regarding inhalation exposure to Shiga toxin-producing Eb_ coli since P2 
reduces the probability of exposure by aerosol. He supported Dr. Clowes' 
suggestion. 
Dr. Gottesman said she wished to respond to certain of Dr. Holmes' concerns. 
She reminded the committee the proposed research with the Shiga toxin 
structual gene is to be performed under P3 containment with E. coli K-12 
host-vector systems. P3 containment conditions severely limit the possibil- 
ity of the organism escaping. In addition, the host in this case would be 
E. coli K-12 which is a debilitated strain. In addition. Dr. Gottesman 
argued that Shiga toxin exists in Eh_ coli strains in nature; thus, the only 
way in vhich a novel organism might be produced by recombinant DNA techniques 
is if the plasmid construct produces higher levels of toxin than strains 
in nature. Dr. Gottesman felt these considerations and the primate data 
indicating that Shiga toxin is not toxic when delivered in the gut address 
most of the concerns . 
Dr. Gottesman moved that RAC recommend experiments involving the cloning 
in coli K-12 of the intact structural gene(s) of Shiga-like toxin of 
E. coli be permitted at P3 + EK1 containment. This is the first request 
in Dr. O'Brien’s April 4 proposal. Dr. Fedoroff seconded the motion. 
Dr. King Holmes noted that he would support the motion as he felt the 
benefits greatly outweigh the risks. By a vote of twenty-one in favor, 
none opposed, and one abstention, the RAC recommended the motion. 
Dr. Gottesman then moved RAC approve the working group recommendation 
that E^ coli host-vector systems expressing the Shiga toxin gene may be 
removed from P3 to P2 containment under the following conditions: 
(1) That the amount of toxiq produced by the modified host- vector 
systems be no greater than that produced by the positive 
control strain, 933 Eh_ coli 0157H7, grown and measured under 
optimal conditions; and 
[478] 
