SEPTEMBER 6-7 - MINUTES OF MEETING 
8 
Dr. Williams summarized the results of the polyoma risk-assessment exper- 
iments. The first reference— in item 708 reports results obtained with 
polyoma DNA cloned in pBR322. The recombinant molecule is not capable 
of producing infection in the mouse test system. On cleavage from the 
recombinant, the polyoma DNA is again infectious. The result indicates 
that polyoma ENA was not excised from the recombinant molecule in the 
mouse. Mice injected with x^76 carrying the recombinant plasmid do not 
be cane infected. 
2 / 
The paper in the second reference- of item 708 describes results obtained 
with lambda-polyoma recombinants. In these experiments, monomer and 
dimer inserts of polyoma in lambda were generated. Lambda recanbinants 
containing a single-copy of polyoma were not infectious. Lambda recombinants 
containing dimers of polyoma were infectious, but less infectious than 
naked polycna DNA. 
Dr. Williams then suirmarized the results in the third reference^f item 
708, a preprint on oncogenicity testing in hamsters. The studies involve 
polyoma DNA inserted in pBR322 (mo none rs ) and inserted in lambda (monomers 
and dimers). Dr. Williams said that none of the hamsters developed 
tumors over a five-month period after receiving a subcutaneous injection 
of x 1776 carrying the polyoma recombinants. He said that in control 
experiments tumor production was observed after cleavage of the polyoma 
recombinants. 
Dr. Williams then briefly described the results of testing E. coli 
K-12 carrying a eukaryotic shotgun mixture ( Saccharonyces cerevisiae) 
for altered pathogenicity. The paper had been distributed to the RAC 
as item 677 for its May 1979 meeting. The authors concluded that the 
shotgun cloning of S. cerevisiae in E. coli K-12 did not yield any 
clone with increased virulence for mice or with increased ability to 
adapt to mouse virulence as compared with E. coli K-12 carrying a 
non-recombinant plasmid. 
1/Israel, Mark A., Chan, Hardy W. , Rowe, Wallace P., and Martin, Malcolm A.: 
Molecular cloning of polyoma virus DNA in Escherichia coli : Plasmid 
vector system. Science, 203: 883-887, 1979. 
2/Chan, Hardy W. , Israel, Mark A., Garon, Claude F. , Rowe, Wallace P. and 
Martin, Malcolm A.: Molecular cloning of polyoma virus DNA in Escherichia 
coli : Lambda phage vector system. Science, 203 : 887-892, 1979. 
3/Israel, M.A., Chan, H.W., Martin, M.A. , Rowe, W.P.: Molecular cloning 
of polyoma virus DNA in Escherichia coli : Oncogenicity testing in 
hamsters. Science, 205: 1140-1142, 1979. 
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