63076 
Federal Register / Vol. 44, No. 213 / Thursday, November 1, 1979 / Notices 
received adequate discussion either at 
the RAC or in the scientific community 
at large: 
(a) Restriction enzyme generated 
fragments of the polyoma genome retain 
the tumorigencity exhibited by polyoma 
DNA. even after incorporation into 
plasmids or lambda particles. Therefore, 
working with subgenomic fragments 
does not represent a form of 
containment, as may have been thought 
previously. Indeed, a recent paper from 
Rowe and Martin's groups (Israel, et al.. 
PSAS. 76. 3713, 1979} shows that 
preparations of polyoma DNA can 
actually have their tumorigencity 
increased to one hundred percent (vs. 
nineteen percent in controls) by 
treatment with certain restriction 
enzymes. Therefore, working with 
subgenamic fragments actually 
represents a new level of hazard. 
(b) Since polyoma DNA and 
subgenomic fragments thereof are 
tumorigenic in the absence of residual 
infectivity, the argument that working 
with the DNA is no more hazardous 
than working with the whole virus, is no 
longer tenable. Specifically, the 
generation of infective particles and 
subsequent spread through the tissue of 
an exposed host is not necessary for a 
tumor to be formed: action on a single 
cell of a host and subsequent replication 
of that transformed cell is all that is 
necessary. 
(c) A corollary of (b) is that the capsid 
of a normal virus may actually represent 
a form of containment which is 
breached in splicing experiments. There 
is good reason to believe that the host 
range for tumorigenicity may be 
extended by the use of subgenomic 
fragments, since unlike the capsid. DNA 
probably does not observe cell surface 
differences. 
(d) The insertion of plasmids or 
lambda particles containing polyoma 
DNA fragments into bacteria represents 
a new route into the ecosystem and a 
new reservior for variation of a material 
which is manifestly an agent of animal 
carcinogenesis. 
(e) The fact that the splice products 
are less effective than the whole virus in 
promoting tumors in polyoma's normal 
host is irrelevant when considered along 
with the creation of quantitatively new 
routes of dissemination of this 
tumorigenic agent. 
I therefore propose in the strongest 
terms that guidelines for containment of 
tumor virus gene splicing experiments 
be raised to P4/EK2 levels rather than 
be further weakened as would result 
from the E. coli K-12 exemption 
proposal of the September 1979 RAC 
meeting. 
Dated: October 25, 1979. 
Donald S. Frederickson. M.D., 
Director. National Institutes of Health. 
(FR Doc T9S37M Filed 10-31-7* *45 am) 
BILUNG CODE 4110-0S-M 
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