Page
1
of
12
PLANT­
INCORPORATED
PROTECTANTS
BASED
ON
PLANT
VIRAL
COAT
PROTEINS
Introduction
A
plant­
incorporated
protectant
(
PIP)
is
a
pesticidal
substance
that
is
intended
to
be
produced
and
used
in
a
living
plant,
or
in
the
produce
thereof1,
and
the
genetic
material
necessary
for
production
of
such
a
pesticidal
substance.
The
term
includes
both
active
and
inert
ingredients.
PIPs
are
regulated
as
pesticides
by
EPA
under
the
Federal
Insecticide,
Fungicide,
and
Rodenticide
Act
(
FIFRA)
because
they
meet
the
FIFRA
definition
of
a
pesticide,
being
intended
for
preventing,
destroying,
repelling,
or
mitigating
a
pest.

PIPs
may
be
genetically
engineered
into
plants2.
Some
specific
genetic
sequences,
when
incorporated
into
a
plant's
genome,
can
endow
the
plant
with
the
ability
to
resist
damage
from
certain
pests.
Plant
virus
coat
protein
PIPs
(
PVCP­
PIPs)
are
PIPs
in
which
the
inserted
genetic
material
is
derived
from
a
plant
virus
sequence
that
encodes
a
coat
protein.
Plant
virus
coat
proteins
encapsidate
the
viral
nucleic
acid
and
are
known
to
have
a
role
in
nearly
every
stage
of
viral
infection
including
replication,
movement
throughout
an
infected
plant,
and
transport
from
plant
to
plant.
Incorporation
of
plant
viral
coat
protein
(
PVCP)
gene
sequences
into
plant
genomes
has
been
found
to
confer
resistance
to
the
virus
from
which
it
was
derived,
and
often
to
related
viruses
(
OECD
Environment
Directorate
1996).

Background
In
1994
EPA
published
its
policy
regarding
regulation
of
PIPs
(
then
called
plant­
pesticides)
under
FIFRA.
Recognizing
the
breadth
of
the
definition
of
a
PIP
and
that
some
PIPs
present
a
lower
overall
risk
and
thus
may
not
require
regulation,
the
Agency
proposed
several
exemptions
to
regulation.
Included
were
two
options
to
exempt
PVCP­
PIPs.
A
full
categorical
exemption
from
regulation
under
FIFRA
was
proposed
for
PVCP­
PIPs
based
on
the
rationale
that
they
generally
pose
a
low
probability
of
risk
to
human
health
or
the
environment.
However,
recognizing
that
other
plants
could
acquire
the
virus
resistance
through
hybridization
with
a
transgenic
plant,
an
alternative
to
a
full
categorical
exemption
was
also
proposed
to
promote
full
discussion
of
this
issue.
Under
this
alternative
exemption
option,
the
Agency
defined
a
set
of
criteria
to
identify
those
viral
coat
protein/
plant
combinations
with
the
lowest
potential
to
confer
selective
advantage
on
wild
or
weedy
plant
relatives.
Only
those
PVCP­
PIPs
so
identified
would
have
been
exempt
from
regulation.
The
1994
policy
statement
described
this
alternative
exemption
as
follows:

Coat
proteins
from
plant
viruses
[
would
be
exempt]
if
the
genetic
material
necessary
to
produce
a
coat
protein
is
introduced
into
a
plant's
genome
and
the
plant
has
at
least
one
of
the
following
characteristics:

1
The
phrase
"
or
produce
thereof"
is
included
in
the
definition
of
a
PIP
to
make
it
clear
that
pesticidal
substances
active
in
the
fruit
or
other
plant
product
for
pesticidal
purposes
are
also
considered
to
be
PIPs.
2
PIPs
may
also
be
found
naturally­
occurring
in
plants
or
may
be
introduced
through
conventional
breeding.
However,
the
focus
here
is
on
PIPs,
specifically
those
based
on
viral
coat
proteins,
that
are
introduced
into
plants
through
genetic
engineering.
Page
2
of
12
(
1)
The
plant
has
no
wild
relatives
in
the
United
States
with
which
it
can
successfully
exchange
genetic
material,
i.
e.,
corn,
tomato,
potato,
soybean,
or
any
other
plant
species
that
EPA
has
determined
has
no
sexually
compatible
wild
relatives
in
the
United
States.

(
2)
It
has
been
demonstrated
to
EPA
that
the
plant
is
incapable
of
successful
genetic
exchange
with
any
existing
wild
relatives
(
e.
g.,
through
male
sterility,
self­
pollination).

(
3)
If
the
plant
can
successfully
exchange
genetic
material
with
wild
relatives,
it
has
been
empirically
demonstrated
to
EPA
that
existing
wild
relatives
are
resistant
or
tolerant
to
the
virus
from
which
the
coat
protein
is
derived
or
that
no
selective
pressure
is
exerted
by
the
virus
in
natural
populations.

Some
proposals
in
the
1994
policy
statement
were
finalized
in
2001.
However,
neither
the
full
nor
alternative
exemption
for
PVCP­
PIPs
was
finalized,
in
part
because
more
recent
information
had
questioned
the
idea
that
PVCP­
PIPs
would
generally
pose
a
low
probability
of
risk
and
would
not
pose
unreasonable
adverse
effects
to
human
health
or
the
environment
in
the
absence
of
any
regulation
under
FIFRA.
For
example,
the
2000
National
Research
Council
(
NRC)
report,
Genetically
Modified
Pest­
Protected
Plants,
recommended
that,

"
EPA
should
not
categorically
exempt
viral
coat
proteins
from
regulation
under
FIFRA.
Rather,
EPA
should
adopt
an
approach,
such
as
the
agency's
alternative
proposal ,
that
allows
the
agency
to
consider
the
gene
transfer
risks
associated
with
the
introduction
of
viral
coat
proteins
to
plants."

In
addition
to
the
risks
associated
with
gene
transfer,
the
2000
NRC
report
considered
other
concerns
associated
with
the
use
of
PVCP­
PIPs,
including
the
potential
for
adverse
effects
following
recombination,
heterologous
encapsidation,
and
synergy.
Although
the
report
concluded
that,
"[
m]
ost
virus­
derived
resistance
genes
are
unlikely
to
present
unusual
or
unmanageable
problems
that
differ
from
those
associated
with
traditional
breeding
for
virus
resistance,"
neither
formulation
of
the
exemption
proposed
in
1994
contained
provisions
that
would
have
enabled
EPA
to
ensure
that
the
risk
management
strategies
suggested
by
the
NRC
would
be
implemented,
e.
g.,
elimination
of
specific
sequences
to
limit
the
potential
for
recombination.

In
2001
the
Agency
reopened
the
comment
period
on
the
PVCP­
PIP
exemption
proposals
and
sought
advice
from
the
public
on
how
best
to
proceed.
EPA
is
in
the
process
of
reevaluating
how
PVCP­
PIPs
will
be
treated
by
the
Agency
in
light
of
comments
and
advice
it
received.
The
Agency
is
reconsidering
the
scientific
merit
and
feasibility
of
exempting
a
subset
of
PVCP­
PIPs
from
regulation
under
FIFRA
as
one
of
several
regulatory
options.
Potential
conditions
intended
to
reduce
the
risks
associated
with
the
use
of
PVCP­
PIPs
are
included
in
the
questions
to
the
panel
to
provide
a
structure
that
may
facilitate
discussion
of
environmental
concerns
raised
with
regard
to
commercial
use
of
PVCP­
PIPs.
Page
3
of
12
Charge
to
the
SAP
EPA
requests
that
the
Scientific
Advisory
Panel
provide
scientific
advice
to
assist
EPA
in
its
evaluation
of
plant­
incorporated
protectants
(
PIPs)
based
on
plant
virus
coat
proteins
(
PVCPPIPs
During
the
public
comment
periods
for
PVCP­
PIPs
in
1994
and
again
in
2001,
the
Agency
received
comments
from
the
scientific
community
that
covered
viewpoints
ranging
from
support
for
a
full
categorical
exemption
to
opposition
to
any
exemption
procedure
for
PVCP­
PIPs.
These
comments
highlighted
several
areas
of
scientific
uncertainty
that
are
addressed
in
our
questions
to
the
panel.
The
Agency
asks
for
the
panel's
scientific
advice
in
three
areas:
gene
flow,
viral
interactions,
and
other
issues.
EPA
seeks
the
assistance
of
the
SAP
in
evaluating
whether
gene
flow
and
viral
interactions
may
pose
environmental
hazards,
and
if
so,
whether
these
concerns
could
be
mitigated
under
certain
circumstances.
EPA
seeks
the
advice
of
the
SAP
to
ensure
that
PVCP­
PIPs
are
appropriately
described
and
to
develop
a
more
complete
technical
record.

Charge
 
Gene
Flow
Gene
flow
from
plants
containing
PVCP­
PIPs
is
a
potential
concern
to
the
extent
that
new
genes
conferring
virus
resistance
may
be
introduced
into
wild
or
weedy
relatives
with
the
potential
either
to
release
them
from
growth
and/
or
reproduction
constraints
imposed
by
naturally
occurring
virus(
es)
or
conversely
to
decrease
their
fitness
through
changes
in
gene
expression.
These
relatives
of
transgenic
plants
may
then
have
the
potential
for
increased
weediness
and/
or
the
ability
to
outcompete
other
species.
Conversely,
plants
also
may
become
less
competitive.

A
broad
review
of
hybridization
between
plants
and
their
wild
relatives,
including
the
potential
for
and
possible
implications
of
the
movement
of
transgenes,
was
recently
published
(
Ellstrand
2003),
and
the
issue
of
introgression
from
genetically
modified
crops
to
their
wild
relatives
was
considered
in
a
recent
review
(
Stewart
et
al.
2003).
In
addition,
several
scientific
review
panels
have
recently
analyzed
the
general
issue
of
gene
flow
with
particular
attention
to
the
regulatory
issues
facing
both
U.
S.
and
foreign
government
agencies
(
National
Research
Council
2000;
GM
Science
Review
Panel
2003)
3.
The
potential
effects
of
gene
flow
to
wild
relatives
specifically
from
plants
containing
PVCP­
PIPs
has
been
addressed
in
a
few
experimental
studies
(
Bartsch
et
al.
1996;
Bartsch
et
al.
2001;
Spencer
&
Snow
2001;
Ilardi
&
Barba
2001;
Fuchs
et
al.
2004a;
Fuchs
et
al.
2004b).
This
issue
is
considered
in
greater
depth
in
several
reviews
(
Bartsch
1997;
Power
2002;
Tepfer
2002).
The
theoretical
possibility
that
gene
flow
from
plants
containing
PVCP­
PIPs
to
wild
or
weedy
relatives
could,
in
some
instances,
lead
to
environmental
impacts
is
widely
accepted.
However,
empirical
or
observational
data
on
the
likelihood
or
magnitude
of
such
impacts
are
lacking.
Consequently
EPA
is
seeking
the
assistance
of
the
SAP
to
attempt
to
reach
a
better
understanding
of
the
circumstances
in
which
the
flow
of
PVCP­
PIPs
from
transgenic
plants
to
wild
or
weedy
relatives
could
occur
and
the
potential
for
adverse
impacts
from
such
gene
flow.

3
The
UK
Government,
the
Scottish
Executive,
the
National
Assembly
for
Wales
and
the
administration
in
Northern
Ireland
have
been
promoting
a
national
dialogue
on
genetic
modification
(
GM)
issues.
One
part
of
this
was
a
review
of
the
science
of
GM,
led
by
Sir
David
King
(
the
Government's
Chief
Scientific
Adviser)
working
with
Professor
Howard
Dalton
(
the
Chief
Scientific
Adviser
to
the
Secretary
of
State
for
the
Environment,
Food
and
Rural
Affairs),
with
independent
advice
from
the
Food
Standards
Agency.
Page
4
of
12
Questions
 
gene
flow
Concerns
about
the
transfer
of
virus
resistance
to
wild
or
weedy
relatives
include
the
assumption
that
such
resistance
might
confer
a
selective
advantage
to
a
wild
or
weedy
relative
that
could
increase
its
competitive
ability
and
potential
to
become
weedy
or
invasive.
The
Agency
would
like
the
panel
to
consider
the
evidence
supporting
this
assumption.

1.
What
scientific
evidence
supports
or
refutes
the
idea
that
plant
viruses
have
significant
effects
on
reproduction,
survival,
and
growth
of
plant
populations
in
natural
settings?
Is
there
scientific
evidence
that
plant
populations
freed
from
viral
pressure
could
have
increased
competitive
ability
leading
to
changes
in
plant
population
dynamics?

In
the
1994
proposal,
EPA
identified
tomato,
potato,
soybean,
and
corn
as
having
no
wild
relatives
in
the
United
States
with
which
they
can
successfully
exchange
genetic
material,
although
the
2002
NRC
report
,
Environmental
Effects
of
Transgenic
Plants,
suggests
that
corn
and
its
wild
relative
Eastern
gamagrass
(
Tripsacum
dactyloides)
might
produce
hybrids
with
some
fertility
at
a
very
low
frequency
in
the
United
States.

2.
Please
comment
on
the
validity
of
the
Agency
list
of
crops
that
have
no
wild
or
weedy
relatives
in
the
United
States
with
which
they
can
produce
viable
hybrids
in
nature
(
i.
e.,
tomato,
potato,
soybean,
and
corn).

3.
Please
identify
other
crops
that
have
no
wild
or
weedy
relatives
in
the
United
States
with
which
they
can
produce
viable
hybrids
in
nature,
e.
g.,
papaya,
peanut,
and/
or
chickpea.

The
Agency
anticipates
the
need
to
evaluate
data
addressing
whether
transgenic
plant
species
are
capable
of
genetic
exchange
with
wild
or
weedy
plant
relatives.
In
general,
EPA
is
focused
on
the
potential
for
genetic
exchange
that
can
occur
in
the
field.
However,
evaluations
of
the
potential
for
genetic
exchange
are
likely
to
include
laboratory
studies
that
are
not
necessarily
an
accurate
indicator
of
plants'
ability
to
exchange
genetic
material
outside
the
lab.

4.
What
laboratory
techniques
used
to
achieve
genetic
exchange
between
species
(
e.
g.,
embryo
rescue,
use
of
intermediate
bridging
crosses,
protoplast
fusion)
are
not
indicative
of
possible
genetic
exchange
between
these
species
in
the
field?
Conversely,
what
techniques,
if
any,
used
in
laboratory
or
greenhouse
experiments
provide
the
most
reliable
indication
of
ability
to
hybridize
in
the
field?

EPA
recognizes
that
it
may
be
possible
to
genetically
engineer
a
plant
such
that
concerns
about
gene
flow
to
wild
or
weedy
relatives
are
significantly
reduced.
However,
according
to
the
2004
NRC
report,
Biological
Confinement
of
Genetically
Engineered
Organisms,
current
techniques
for
bioconfinement
(
e.
g.,
sterile
triploids,
male
sterility)
are
imperfect
and
are
not
guaranteed
to
eliminate
entirely
gene
flow
to
existing
wild
relatives.
Recent
modeling
studies
suggest
Page
5
of
12
imperfections
in
bioconfinement
could
result
in
significant
levels
of
gene
introgression
in
compatible
plant
relatives
over
a
period
of
decades
(
Haygood
et
al.
2004).

5.
Given
that
current
bioconfinement
techniques
are
not
100%
effective,
what
would
the
environmental
implications
be
of
extremely
low
transfer
rates
of
virus­
resistance
genes
over
time?

EPA
recognizes
that
concerns
about
gene
flow
to
wild
or
weedy
relatives
may
be
ameliorated
if
the
introduced
virus­
resistance
trait
would
give
little
or
no
selective
advantage
to
the
recipient
plant,
as
would
occur
if
the
plant
were
already
tolerant
or
resistant4
to
the
virus
to
which
resistance
is
conferred.
It
is
obvious
that
such
resistance
does
exist
in
some
populations
because
traditional
breeding
for
resistance
relies
on
finding
a
source
of
resistance
within
related
cultivated
species,
old
varieties,
or
wild
species
(
Khetarpal
et
al.
1998).

6.
Please
comment
on
the
prevalence
of
tolerance
and/
or
resistance
to
viruses
in
wild
relatives
of
crops.

7.
Please
specify
techniques
that
do
or
do
not
provide
measures
of
tolerance
and/
or
resistance
that
are
relevant
to
field
conditions.

8.
How
do
environmental
or
other
factors
(
e.
g.,
temporal
variations)
affect
tolerance
and/
or
resistance?
Given
the
expected
variability,
what
measures
of
tolerance
and/
or
resistance
would
be
reliable?

9.
What
would
be
the
ecological
significance
if
a
plant
population
acquired
a
small
increase
in
viral
tolerance
and/
or
resistance
above
a
naturally­
occurring
level?

Based
on
the
hypothesis
that
concerns
about
the
consequences
of
gene
flow
to
a
wild
or
weedy
relative
in
the
United
States
may
be
negligible
in
certain
cases,
the
Agency
is
considering
whether
there
are
mechanisms
to
adequately
address
concerns
associated
with
gene
flow
so
that
certain
types
of
VCPs
would
be
of
such
low
risk
that
they
would
not
need
to
be
regulated
by
EPA.
Below
are
examples
of
three
conditions
(
modified
from
those
proposed
in
1994)
that
are
intended
to
significantly
reduce
any
potential
adverse
effects
of
gene
flow
with
plants
containing
a
PVCP­
PIP.

(
1)
The
plant
into
which
the
PVCP­
PIP
has
been
inserted
has
no
wild
or
weedy
relatives
in
the
United
States
with
which
it
can
produce
viable
hybrids
in
nature,
e.
g.,
corn,
tomato,
potato,
or
soybean;
or
(
2)
Genetic
exchange
between
the
plant
into
which
the
PVCP­
PIP
has
been
inserted
and
any
existing
wild
or
weedy
relatives
is
substantially
reduced
by
modifying
the
plant
with
a
scientifically
documented
method
(
e.
g.,
through
male
sterility);
or
(
3)
It
has
been
empirically
demonstrated
that
all
existing
wild
or
weedy
relatives
in
the
United
States
with
which
the
plant
can
produce
a
viable
hybrid
are
tolerant
or
resistant
to
the
virus
from
which
the
coat
protein
is
derived.

4
See
Appendix
for
definitions.
Page
6
of
12
10.
Please
comment
on
how
necessary
and/
or
sufficient
these
conditions
are
to
minimize
the
potential
for
the
PVCP­
PIP
to
harm
the
environment
through
gene
flow
from
the
plant
containing
the
PVCP­
PIP
to
wild
or
weedy
relatives.
Would
any
other
conditions
work
as
well
or
better?

Charge
 
Viral
Interactions
Interactions
between
introduced
plant
virus
sequences
and
other
invading
viruses
in
transgenic
plants
(
e.
g.,
during
recombination
or
heterologous
encapsidation)
may
be
a
concern
to
the
extent
that
such
events
may
increase
in
frequency
or
be
unlike
those
expected
to
occur
in
nature.
It
has
been
hypothesized
that
such
events
could
lead
to
the
creation
of
viruses
with
new
disease
states
or
transmission
properties.
The
Agency
is
evaluating
the
circumstances
that
might
increase
the
potential
for
such
events
to
occur
and
the
potential
environmental
consequences
of
novel
viral
interactions5
in
light
of
the
2000
NRC
report
which
stated
that,
"[
m]
ost
virus­
derived
resistance
genes
are
unlikely
to
present
unusual
or
unmanageable
problems
that
differ
from
those
associated
with
traditional
breeding
for
virus
resistance."
The
report
went
on
to
suggest
that
risks
might
be
managed
by
particular
ways
of
engineering
transgenes6.
However,
under
either
of
the
1994
proposed
exemptions,
the
Agency
would
be
unable
to
ensure
that
such
strategies
were
implemented.
The
Agency's
literature
review,
"
Viral
interactions
in
viral
coat
protein
transgenic
plants,"
discusses
possible
ways
of
managing
these
potential
risks
in
detail.

Questions
 
viral
interactions
Viral
interactions
may
occur
in
natural,
mixed
infections
which
are
common
in
plants.
Hypothetical
concerns
related
to
potential
adverse
effects
resulting
from
viral
interactions
between
infecting
viruses
and
PVCP­
PIPs
in
transgenic
plants
may
be
attributed
to
opportunities
for
interactions
not
expected
to
occur
in
nature.
EPA
is
interested
in
evaluating
the
significance
of
novel
viral
interactions
involving
a
viral
transgene7.

11.
To
what
extent
are
novel
viral
interactions
(
e.
g.,
recombination,
heterologous
encapsidation)
involving
a
viral
transgene
an
environmental
concern?

Mixed
viral
infections
can
be
extremely
common
in
crops
and
other
plants.
However,
scientific
uncertainty
exists
as
to
whether
recombination
and
heterologous
encapsidation
would
occur
more
or
less
frequently
in
the
case
of
a
viral
transgene
and
an
infecting
virus
interaction
as
5
See
Appendix
for
definition
of
novel
viral
interactions.
6
The
report
says,
"[
c]
an
transgenes
be
engineered
to
reduce
or
eliminate
the
risk
that
recombination
will
spawn
new
pathogens?
Evidence
suggests
that
elimination
of
genome
replication­
control
sequences
from
transgenes
can
limit
recombination
and
therefore
risk...
Furthermore,
strategies
to
produce
resistance­
mediating
transgenes
that
encode
nonfunction
proteins
or
no
protein
can
be
used
effectively
against
viruses.
For
example,
resistant
plants
that
express
nontranslatable
RNA
can
confer
immunity
through
induction
of
post­
transcriptional
gene
silencing "
(
National
Research
Council
2000;
pg.
94)
7
See
EPA
literature
review
"
Viral
Interactions
in
Viral
Coat
Protein
Transgenic
Plants"
pp.
15­
16.
Page
7
of
12
compared
to
such
interactions
in
mixed
infections
of
a
transgenic
plant's
non­
bioengineered
counterpart8.

12.
What
conclusions
can
be
drawn
as
to
whether
the
likelihood
of
recombination
and/
or
heterologous
encapsidation
would
be
increased
or
decreased
in
a
transgenic
plant
compared
to
its
non­
bioengineered
counterpart?

A
number
of
methods
for
reducing
the
frequency
of
recombination
and
heterologous
encapsidation
have
been
identified.
While
the
effectiveness
of
these
techniques
has
been
verified
for
particular
cases,
their
applicability
to
all
PVCP­
PIPs
is
unclear.
Recognizing
that
it
would
be
difficult
for
a
product
developer
to
measure
rates
of
recombination,
heterologous
encapsidation,
or
vector
transmission
under
field
conditions,
EPA
is
considering
whether
it
would
be
necessary
to
verify
that
such
methods
worked
in
any
particular
instance
by
measuring
rates
in
modified
versus
unmodified
plants.

13.
How
effective
is
deleting
the
3'
untranslated
region
of
the
PVCP
gene
as
a
method
for
reducing
the
frequency
of
recombination
in
the
region
of
the
PVCP
gene?
Is
this
method
universally
applicable
to
all
potential
PVCP­
PIP
constructs?
Would
any
other
methods
work
as
well
or
better?
Which
methods
are
sufficiently
effective
and
reproducible
such
that
actual
measurement
of
rates
to
verify
rate
reduction
would
be
unnecessary?

14.
Are
any
methods
for
inhibiting
heterologous
encapsidation
or
transmission
by
insect
vectors
universally
applicable
to
all
PVCP­
PIPs?
Which
methods
are
sufficiently
effective
and
reproducible
such
that
actual
measurement
of
rates
to
verify
rate
reduction
would
be
unnecessary?

15.
How
technically
feasible
would
it
be
to
measure
rates
of
recombination,
heterologous
encapsidation,
and
vector
transmission
in
PVCP­
PIP
transgenic
plants
in
order
to
show
that
rates
are
reduced?

EPA
recognizes
that
scientific
disagreement
exists
as
to
the
likelihood
of
environmental
impacts
due
to
novel
viral
interactions
in
transgenic
plants
modified
with
PVCP­
PIPs.
The
Agency
is
considering
whether
there
are
available
mechanisms
to
adequately
address
concerns
associated
with
novel
viral
interactions
so
that
certain
types
of
PVCP­
PIPs
would
be
of
such
low
risk
that
they
would
not
need
to
be
regulated
by
EPA.
Below
are
examples
of
conditions
that
might
significantly
reduce
either
the
novelty
[(
1)
and
(
2)]
or
frequency
[(
3)
and
(
4)]
of
viral
interactions
in
PVCP­
PIP
transgenic
plants.

(
1)
The
genetic
material
of
the
PVCP­
PIP
is
translated
and/
or
transcribed
in
the
same
cells,
tissues,
and
developmental
stages
naturally
infected9
by
every
virus
from
which
any
segment
of
a
coat
protein
gene
used
in
the
PVCP­
PIP
was
derived.

8
See
EPA
literature
review
"
Viral
Interactions
in
Viral
Coat
Protein
Transgenic
Plants"
pp.
14­
15.
9
See
Appendix
for
definition
of
naturally
infects.
Page
8
of
12
(
2)
The
genetic
material
of
the
PVCP­
PIP
contains
coat
protein
genes
or
segments
of
coat
protein
genes
from
viruses
established
throughout
the
regions
where
the
crop
is
planted
in
the
United
States
and
that
naturally
infect
the
crop
into
which
the
genes
have
been
inserted.

(
3)
The
PVCP­
PIP
has
been
modified
by
a
method
scientifically
documented
to
minimize
recombination,
(
e.
g.,
deletion
of
the
3'
untranslated
region
of
the
coat
protein
gene).

(
4)
The
PVCP­
PIP
has
been
modified
by
a
method
scientifically
documented
to
minimize
heterologous
encapsidation
or
vector
transmission,
or
there
is
minimal
potential
for
heterologous
encapsidation
because
no
protein
from
the
introduced
PVCP­
PIP
is
produced
in
the
transgenic
plant
or
this
virus
does
not
participate
in
heterologous
encapsidation
in
nature.

16.
Please
comment
on
how
necessary
and/
or
sufficient
each
of
these
conditions
is
to
minimize
the
potential
for
novel
viral
interactions.
Please
address
specifically
what
combination
would
be
most
effective
or
what
conditions
could
be
modified,
added,
or
deleted
to
ensure
that
potential
consequences
of
novel
viral
interactions
in
PVCP­
PIP
transgenic
plants
are
minimized.

Other
questions
In
1994
EPA
proposed
exempting
plant
viral
coat
proteins
from
the
requirement
of
a
food
tolerance
under
the
Federal
Food,
Drug,
and
Cosmetic
Act10
based
on
rationale
that
(
1)
virus
infected
plants
have
always
been
a
part
of
the
human
and
domestic
animal
food
supply
and
(
2)
plant
viruses
have
never
been
shown
to
be
infectious
to
humans
or
mammals.
The
safety
of
consuming
plant
virus
genes
has
been
supported
by
experimental
work
(
Chen
et
al.
2003;
Rogan
et
al.
2000;
Shinmoto
et
al.
1995)
and
expert
consultations
including
the
2000
NRC
report
which
concluded
that,
"
viral
coat
proteins
in
transgenic
pest­
protected
plants
are
not
expected
to
jeopardize
human
health
because
consumers
already
ingest
these
compounds
in
nontransgenic
food."
However,
EPA
recognizes
that
PVCP­
PIP
developers
may
wish
to
modify
the
PVCP­
PIP
construct
and
that
some
methods
of
mitigating
potential
risks
associated
with
recombination
and
heterologous
encapsidation
might
actually
require
them
to
do
so.
Such
modifications
might
result
in
changes
to
the
protein(
s)
produced
thus
creating
potential
food
safety
concerns,
e.
g.,
inadvertent
production
of
new
toxins
or
allergens
(
Day
1996).
Modifications
of
the
construct
and
alteration
of
the
proteins
produced
creates
the
potential
for
health
impacts
on
non­
target
species
as
well
as
humans.

17.
To
what
degree
and
in
what
ways
might
a
PVCP
gene
be
modified
(
e.
g.,
through
truncations,
deletions,
insertions,
or
point
mutations)
while
still
retaining
scientific
support
for
the
idea
that
humans
have
consumed
the
products
of
such
genes
for
generations
and
that
such
products
therefore
present
no
new
dietary
exposures?

18.
What
are
the
potential
adverse
effects,
if
any,
of
such
modifications
on
nontarget
species
(
e.
g.,
wildlife
and
insects
that
consume
the
PVCP­
PIP)?

10
EPA
determines
whether
limits
(
tolerances)
should
be
set
on
the
amount
of
residues
of
PVCP­
PIPs
in
food
derived
from
the
improved
plant.
When
there
is
substantial
information
indicating
safety
and
history
of
safe
use,
the
developer
may
request
an
exemption
from
the
requirement
of
a
tolerance.
Although
a
general
tolerance
exemption
for
all
PVCP­
PIPs
has
not
been
finalized,
tolerance
exemptions
for
specific
PVCP­
PIPs
have
been
.
They
can
be
found
in
40
CFR
Part
180.1182
(
potato),
180.1184
(
watermelon),
180.1185
(
papaya),
and
180.1186
(
cucumber).
Page
9
of
12
Modifications
of
the
construct
may
also
potentially
create
the
opportunity
for
novel
viral
interactions
because
the
inserted
virus
sequences
could
be
unlike
any
that
occur
naturally.

19.
To
what
degree
and
in
what
ways
might
a
PVCP
gene
be
modified
(
e.
g.,
through
truncations,
deletions,
insertions,
or
point
mutations)
before
it
would
be
a
concern
that
novel
viral
interactions
due
to
the
modifications
could
occur
because
the
PVCP
gene
would
be
significantly
different
from
any
existing
in
nature?

The
potential
risk
issues
identified
in
this
paper
are
specific
to
virus­
resistant
transgenic
plants.
However,
the
Agency
recognizes
that
it
may
be
necessary
to
evaluate
other
information
related
to
the
PVCP­
PIP.

20.
Would
any
additional
requirements
related
to
PVCP­
PIP
identity
and
composition
(
e.
g.,
demonstration
that
the
transgene
has
been
stably
inserted)
be
needed
for
significant
reduction
of
risks
associated
with
PVCP­
PIPs?

21.
Are
there
any
considerations
beyond
gene
flow,
recombination,
and
heterologous
encapsidation
as
posed
in
the
preceding
questions
that
the
Agency
should
consider
in
evaluating
the
risk
potential
of
PVCP­
PIPs
(
e.
g.,
synergy)?
Page
10
of
12
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Appendix:
Definitions
Resistant,
when
referring
to
PVCP­
PIPs
only,
means
the
plant
is
not
infected
by
or
is
a
non­
host
of
the
virus
concerned.

Naturally
infects
means
a
naturally
occurring
virus
is
transmitted
to
a
plant
by
direct
plant­
toplant
contact,
inanimate
objects,
or
vectors
such
as
pollen,
arthropods,
nematodes,
or
fungi;
and
the
virus
replicates
and
moves
within
the
recipient
plant.
It
does
not
include
human
intervention,
e.
g.,
manual
inoculation.

Novel
viral
interaction
means
interaction
between
portions
of
two
or
more
different
viruses
(
e.
g.,
through
recombination
or
heterologous
encapsidation)
not
expected
to
occur
in
a
mixed
viral
infection
found
in
nature.

PVCP­
PIP
means
a
plant­
incorporated
protectant
created
from
the
gene,
or
a
segment
of
the
gene,
that
codes
for
a
coat
protein
of
a
virus
that
naturally
infects
crop
plants.

Tolerant,
when
referring
to
PVCP­
PIPs
only,
means
the
plant
is
able
to
sustain
the
effects
of
a
virus
infection
with
negligible
or
mild
symptom
expression
and
negligible
or
mild
effects
on
fitness
or
growth
despite
the
presence
of
the
virus
within
the
host.
