MINUTES OF MEETING - March 6-7 
12 
autonomously or that less than two-thirds of viruses from different Fami- 
lies can fully complement each other's genetic composition. 
Dr. Goldstein asked whether the genome of one type of virus could be 
packaged inside the coat of another virus. Dr. Baltimore replied that 
transcaps idat ion between members of two different animal virus Families 
has never been observed. 
Dr. Campbell asked whether low-grade contamination of cells in culture by 
helper virus is possible. Dr. Dcwdle of CDC said that such contamination 
occurs, generally with viruses being used in the laboratory. Dr. Gottesman 
questioned whether PI containment is appropriate for these types of experi- 
ments. Dr. Baltimore replied that containment higher than PI is used in 
a tissue culture laboratory to prevent contamination of the cell cultures. 
Ms. King noted that Dr. Rowe had previously solicited the opinion of several 
eminent virologists on an earlier version of this proposal, but not on this 
most recent version. She said she would feel more comfortable if additional 
comment could be solicited. 
Dr. Gottesman then suggested that the RAC vote on each part of the proposal 
separately. She said the questions which must be addressed when evalua- 
ting part one [Sections III-C-1-e, Ill-C-l-e-(l) and III-C-l-e-(l)-(a) 
of the proposal] are: (1) Is exemption of two-thirds of a eukaryotic 
viral gencme acceptable in every case; (2) could fragments of viruses of 
different Families reconstitute to produce a viable virus under these 
conditions; and (3) what is the probability of adventitious rescue either 
by cryptic viruses or environmental contaminants. She felt the greatest 
uncertainty existed concerning the third question and suggested it could 
perhaps be dealt with either by including a cautioning footnote or by 
raising containment to P2. 
Dr. Baltimore suggested that "in absence of helper virus" be deleted and 
the following sentence be added to the proposal: 
"For such experiments, it must be shown that the cells 
lack helper virus for the specific Families of defective 
viruses being used." 
Dr. Gottesman suggested that the last two sentences of III-C-l-e-(l)-(a) 
be struck. This would provide for a more conservative review procedure. 
Dr. Gottesman moved acceptance of part one of the proposal as amended. 
Dr. Setlow then called the vote. This part was approved by the RAC by a 
vote of thirteen in favor, three opposed, and five abstentions. 
[ 47 ] 
