DEPARTMENT OF HEALTH. EDUCATION. AND WELFARE 
PUBLIC HEALTH SERVICE 
NATIONAL INSTITUTES OF HEALTH 
BETHESDA. MARYLAND 20205 
January 25, 1980 
MEMORANDUM 
TO: Institutional Biosafety Committees and Principal Investigators 
FROM: Director 
Office of Recombinant DNA Activities, NIAID 
SUBJECT: Transition to Revised Guidelines for Recombinant DNA Research 
I. Revised Guidelines for Recombinant DNA Research 
Revised Guidelines for Research Involving Recombinant DNA Molecules 
will be published in the Federal Register within the next week, 
and will be effective on the date of publication. Copies of the 
revised Guidelines and a revised Administrative Practices Supplement 
will be distributed in the near future. 
The Guidelines have been revised to incorporate a new Section III-O, 
"Classification of Experiments Using the E\ coli K-12 Host-Vector 
Systems," and other changes that have been made since the Guidelines 
were last published in their entirety in December 1978. 
II. Experiments Involving E. coli K-12 Host-Vector Systems 
The revised Guidelines do not provide an exemption for most 
experiments involving E. coli K-12 host-vector systems. They 
require the use of PI physical containment and EKl host-vector 
systems as defined below. The administrative requirements for 
these experiments have been changed. 
The text of Section III-O is as follows: 
[ 1 ] 
