Technical Information 
Detailed instructions concerning data to be submitted for certification can 
be obtained from the Office of Recombinant DNA Activities. NIH, Bethesda, 
Md. 20205. Information on tests for EK2 phage certification were presented 
in Volume 1 Number 1 and for EK2 plasmid certification in this issue. 
Certification of a given system does not extend to modifications of either 
the host or vector component. All modified systems are subject to indepen¬ 
dent confirmation and approval. The procedures for certification are 
presented in the Guidelines (Federal Register, December 22, 1978, pp. 
60108-60131). Presented in the following tables are the certified EK2 host- 
vector systems. 
Plasmid Systems 
Vector 
Host 
Date Certified 
Literature 
References 
pSCIOI 
X1776 
12-6-1976 
1,2 
pCRr 
X1776 
(decertified 
8-21-78) 
1,3,4 
pMB9 
X1776 
4-18-1977 
1,5,6,7 
pBR313 
X1776 
7-7-1977 
1,7 
pBR322 
X1776 
7-7-1977 
1,7 
The four host-plasmid systems that have been certified for use as EK2 host-vector systems are listed in the above Table. 
* Since the time of certification of the systems employing pSCI 01 and pCRI, a new set of criteria for EK2 certification has been 
approved by the Recombinant DNA Molecule Program Advisory Committee. These criteria have been met by the systems employing 
the plasmids pMB9, pBR313, and pBR322. The Committee recommended the decertification of x1776 (pCRI) as an EK2 host-vector 
system on the grounds it is inferior with regard to transmissabllity and further recommended that this system not be allowed for any 
new cloning since superior plasmids are available. It is therefore the decision of NIH that x1776 (pCRI) is decertified as an EK2 host- 
vector system. However, existing clones need not be destroyed. 
25 
