6 
Dr. Gottesman asked whether the working group would support a reccmmendation 
to exenpt experiments in tissue culture involving less than one-third of a 
viral gencme of a specific viral Family. 
Dr. Joklik preferred that experiments involving less than one-half of the 
gencme of a specific viral Family be exempted from the NIH Guidelines. 
Dr. Mulligan said he did not see a great deal of difference between exempting 
one-third and one-half of the genome. He preferred the working group recommend 
experiments involving less than one-half of a viral genome be exempted from 
the NIH Guidelines. 
Dr. Anderson thought the working group should suggest experiments involving 
less than one-half of nonprimate virus gencmes and less than one-third of the 
gencme of primate viruses be exempted frcm the NIH Guidelines. Dr. Joklik agreed 
primate retroviruses may warrant special evaluation in terms of rescue in 
tissue culture systems. 
Dr. Gottesman asked how large viruses, such as Herpes viruses, should be handled 
under such a proposal. 
Dr. Mulligan said language referring to two-thirds of a genome would apply 
primarily to smaller viruses; it is not possible to clone two-thirds of large 
viruses such as the Herpes viruses. 
Dr. Mulligan suggested Herpes viridae and other large viruses are a special 
case which might be distinguished in any language developed as part of a recom- 
mendation for modifying the NIH Guidelines. Dr. Rapp agreed; he reasoned 
Herpes viruses deleted for one-half of the gencme might be viable in tissue 
culture since Herpes viruses range in size frcm 70 x 10^ to 150 x 10^ daltons. 
Dr. Anderson suggested the working group might specifically develop language to 
apply to virus fragments smaller than 50 kilobases. 
Dr. Gottesman said she preferred simple language and thought a strong argument 
for exempting one-third of a viral gencme in tissue culture systems was that 
few mechanisms exist for spread of these small pieces of viruses. 
Dr. Landy said a modification exempting tissue culture experiments involving 
less than one-third of a viral genome of a given virus Family would reduce the 
IBC workload enormously and would achieve the working group goal of eliminating 
the requirement to register experiments involving single viral genes. 
Dr. Simpson said he would attempt to develop with the advice and assistance of 
the NIH IBC a proposal to modify the NIH Guidelines. He would request that RAC 
consider this proposal . The working group agreed. 
Dr. Gottesman asked the working group to discuss the issue of exempting single 
viral genes in tissue culture experiments while distinguishing between the 
protein product of oncogenes and the products of genes such as the TK gene. 
[ 445 ] 
