NOTICES 
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and will be conducted under the pre- 
scribed physical and biological con- 
tainment conditions. (See Section IV- 
E-l-b-UMc).) 
III-C-l-e-GMb). Under physical 
and biological containment conditions 
to be determined by NIHC45] when a 
viral helper will be used to propagate 
DNA sequences from prokaryotiq or 
eukaryotic organisms. (See Section IV- 
E-l-b-(3Mc).) 
III-C-l-e-<2). Experiments involving 
the use of other whole or defective 
virus genomes to propagate DNA se- 
quences from prokaryotic or eukaryo- 
tic organisms (and viruses), or as vec- 
tors to transform nonpermlsslve cells, 
will be evaluated by NIH on a case-by- 
case basis[45] and will be conducted 
under the prescribed physical and bio- 
logical containment conditions. (See 
Section IV-E-l-b-(3)-<c).) 
NIH will also review on a case-by- 
case basis[451 all experiments involv- 
ing the use of virus vectors in animals 
and will prescribe the physical and 
biological containment conditions ap- 
propriate for such studies. (See Sec- 
tion IV-E-l-b-(3)-(c).) 
III-C-2. Invertebrate Host-Vector 
Systems in Which Insect Viruses Are 
Used to Propagate Other DNA Seg- 
ments. As soon as information be- 
comes available on the host range re- 
strictions and on the infectivlty. per 
sistence. and integration of the viral 
DNA in vertebrate and invertebrate 
cells, experiments involving the use of 
insect viruses to propagate DNA se- 
quences will be evaluated by NIH on a 
case-by-case basls[45] and will be con- 
ducted under the prescribed physical 
and biological containment conditions. 
(See Section IV-E-l-b-(3)-<c).) 
III-C-3. Plant Viral Host-Vector Sys- 
tems. The DNA plant viruses which 
could currently serve as vectors and 
cloning genes in plants and plant cell 
protoplasts are Cauliflower Mosaic 
Virus (CaMV) and its close relatives 
[2A] which have relaxed circular 
double-stranded DNA geromes with a 
molecular weight of 4.5 x 10* and 
Bean Golden Mosaic Virus (BGMV) 
and related viruses with small (10* dal- 
tons) single-stranded DNA genomes. 
CaMV is spread in nature by aphids, in 
which it survives for a few hours. 
Spontaneous mutants of CaMV which 
lack a factor essential for aphid trans- 
mission arise frequently. BGMV is 
spread in nature by whiteflies, and 
certain other single-stranded DNA 
plant viruses are transmitted by leaf- 
hoppers. 
The DNA plant viruses have narrow 
host ranges and are relatively difficult 
to transmit mechanically to plants. 
For this reason, they are most unlike- 
ly to be accidentally transmitted from 
spillage of purified virus preparations. 
When these viruses are used as vec- 
tors in intact plants, or propagative 
plant parts, the plants shall be grown 
under PI conditions— that is, in either 
a limited access greenhouse or plant 
growth cabinet which is insect-restric- 
tive. preferably with positive air pres- 
sure. C2A] and in which an Insect fu- 
migation regime is maintained. Soil, 
plant pots, and unwanted infected ma- 
terials shall be removed from the 
greenhouse or cabinet in sealed insect- 
proof containers and sterilized. It is 
not necessary to sterilize run-off water 
from the infected plants, as this is not 
a plausible route for secondary infec- 
tion. When the viruses are used as vec- 
tors in tissue cultures or in small 
plants in axenic cultures, no special 
containment is necessary. Infected 
plant materials which have to be re- 
moved from the greenhouse or cabinet 
for further research shall be main- 
tained under insect-restrictive condi- 
tions. These measures provide an en- 
tirely adequate degree of containment. 
They are similar to those required in 
many countries for licensed handling 
of “exotic” plant viruses. 
The CaMV strain used as a cloning 
vector shall be a mutant that lacks the 
aphid transmission factor. 
The viruses or their DNA may also 
be useful as vectors to introduce genes 
into plant protoplasts. The fragility of 
plant protoplasts combined with the 
properties of the viruses provides ade- 
quate safety. Since no risk to the envi- 
ronment from the use of the DNA 
plant virus/protoplast system is envis- 
aged. no special containment is neces- 
sary. except as described in the follow- 
ing paragraph. 
Experiments involving the use of 
plant virus genomes to propagate DNA 
sequences from eukaryotic viruses will 
be evaluated by NIH on a case-by-case 
basis [45] and will be conducted under 
the prescribed physical and biological 
containment conditions. (See Section 
rv-E-l-b-(3Mc).) 
FEDERAL REGISTER, VOL 43, NO. 247— FRIDAY, DECEMBER 22, 197R 
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