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Nepovirus
Group
-
Tobacco
Ringspot
Virus
(TRSV),
Respberry
Virus
(RRV) |
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Nepovirus
Group
-
Tobacco
Ringspot
Virus
(TRSV),
Respberry
Virus
(RRV) - The group contains isometric multiparticulate viruses with two or three types of particles with a uniform diameter of 28-30 nm.
Most members possess top particles which lack nucleic acid. The bottom particles contain 38-40% nucleic acid. Middle particles are present in most members of the group. They contain 28-31 % nucleic acid.
The
different
types
of
particles
have
the
same
size.
Heterogeneity
is
due
to
different
amounts
of
nucleic
acid.
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Tobacco
ringspot
virus
(TRSV)
Tobacco
ringspot
virus
is
an
isometric
virus,
the
particles
of
which
sediment
as
three
nucleoprotein
components
with
sedimentation
coefficients
of
125S,
958
and
50S.
All
the
three
particle
types
have
a
diameter
of
about
30-nm.
Only
two
particle
types
contain
nucleic
acids.
There
are
two
kinds
of
nucleic
acids,
a
smaller
RNA-l
and
a
larger,
RNA-2.
RNA-l
is
infectious
by
itself,
but
shows
enhanced
infectivity
with
RNA-2.
Only
the
bottom
particles
are
infectious.
They
are
of
two
buoyant
density
classes
(heterogenous
RNA),
one
infectious
and
one
non
infectious.
Nucleic
acid
from
the
non
infectious
middle
particles
is
non
infectious.
TRSV
has
a
wide
host
range
and
induces
ringspot
and
mottle
symptoms.
Nematodes
are
vectors.
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Raspberry
ringspot
virus
(RRV)
Raspberry
ringspot
virus
contains
2-3
particle
types
containing
0.30
and
about
44%
RNA.
The
bottom
particles
by
themselves
are
infective.
Infectivity
is
however,
increased
by
addition
of
M
particles.
Polyacrylamide
gel
analysis
shows
two
types
of
RNA,
RNA-l(MW
2.4
x
106)
and
RNA-2
(MW
l.4X
106).
The
bottom
particles
contain
either
one
mOlecu1e
of
RNA-l
or
two
molecules
of
RNA-2.
The
middle
particles
contain
RNA-2.
RNA-l
preparations
are
infective.
Infectivity1S
greatly
increased
by
the
addition
of
RNA-2.
RNA-2
preparations
by
themselves
are
not
infective.
In
contrast
to
PEMV,
the
gene
for
the
capsid
protein
is
located
on
the
smaller
RNA
species.
Tomato
ringspot
virus
does
not
produce
middle
particles.
Grapevine
chrome
mosaic
virus
produces
only
middle
and
bottom
particles.
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