Alternative sampling strategies for passive classical and African swine fever surveillance in wild boar--extension towards African swine fever virus antibody detection


Blome, S.; Goller, K.V.; Petrov, A.; Dräger, C.; Pietschmann, J.; Beer, M.

Veterinary Microbiology 174(3-4): 607-608

2015


Veterinary
Microbiology
174
(2014)
607-608
nzgrai,r,y
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y
Contents
lists
available
at
ScienceDirect
Veterinary
Microbiology
F
T
1,
17
-
s
-
TTIET
,
journal
homepage:
www.elsevier.com/locate/vetmic
Letter
to
the
Editor
Alternative
sampling
strategies
for
passive
classical
and
African
swine
fever
surveillance
in
wild
boar
Extension
towards
African
swine
fever
virus
antibody
detection
CrossMark
To
the
Editor,
We
recently
reported
on
the
use
of
blood
swab
samples
for
passive
classical
and
African
swine
fever
(CSF
and
ASF)
surveillance
in
wild
boar
(Petrov
et
al.,
in
press).
Upon
availability
of
the
article
online,
we
were
asked
by
national
and
international
colleagues
whether
this
approach
would
be
suitable
also
for
antibody
detection.
While
antibody
detection
might
not
be
the
primary
focus
of
diagnostic
investigations
in
fallen
animals,
we
think
that
an
approach
that
would
allow
both
pathogen
and
antibody
detection
in
one
easy-to-collect
sample
matrix,
combined
with
simple
shipment,
and
long-term
storage,
would
be
optimal
under
field
conditions.
For
this
reason,
we
tried
to
rapidly
answer
this
question
on
a
limited
set
of
sero-positive
and
sero-negative
blood
samples
from
animal
experiments.
Given
the
current
epidemiological
situation
of
ASF
in
the
European
Union
wild
boar
population
(cases
in
several
Eastern
Member
States
with
a
tendency
to
spread,
see
OIE
WAHID),
we
feel
that
the
audience
of
Veterinary
Microbiology
would
benefit
from
a
brief
addendum
to
the
above-mentioned
article.
For
this
reason,
we
report
on
the
outcome
of
our
initial
studies
here,
while
further
validation
is
still
in
progress.
1.
Study
design
and
outcome
A
total
of
42
porcine
EDTA
blood
samples
were
employed
to
test
applicability
of
swab
fragments
for
antibody
detection.
The
expected
status
of
the
blood
sample
was
related
to
the
corresponding
serum
sample
of
the
same
animal
and
sampling
day.
The
result
of
the
p72
antibody
ELISA
(Ingezim
PPA
Compac,
Ingenasa,
Madrid,
Spain)
was
used
as
a
reference.
Genotube
swabs
(Prionics,
Zurich,
Switzerland),
were
dipped
into the
respective
blood
sample
and
left
to
dry
for
at
least
12
h
at
room
temperature.
Thereafter,
diamond-shaped
fragments
(app.
5
mm
lateral
length)
were
cut
with
sterile
scissors
and
transferred
to
the
ELISA
system.
To
test
samples
close
to
the
"worst-case-scenario",
30
samples
were
included
that
http://dx.doi.org/10.1016/j.vetmic.2014.09.018
0378-1135/©
2014
Elsevier
B.V.
All
rights
reserved.
had
been
stored
for
more
than
21
months
at
4
°C.
This
set
comprised
12
samples
from
sero-negative
animals,
and
18
samples
from
sero-positive
animals.
The
latter
had
been
immunized
twice
with
an
inactivated
preparation
of
genotype
II
ASFV
Armenia08
(Blome
et
al.,
2014).
Samples
were
included
from
days
28
to
41
post
immunization.
The
second
set
of
samples
comprised
animals
that
had
been
inoculated
with
ASFV
OURT88/3
(genotype
I,
non-hemad-
sorbing).
These
samples
(n
=
10)
had
been
taken
29
days
post
inoculation
and
were
stored
approximately
1
month
at
4
°C.
Also
here,
negative
animals
(n
=
2)
were
included.
To
compare
the
performance
with
dried
blood
on
filter
papers
as
foreseen
in
the
ELISA
protocol
(see
below),
we
tested
14
samples
also
on
this
matrix
(the
second
set
of
samples
and
two
long-term
storage
samples,
see
Table
1).
The
commercially
available
ID
Screen®
African
Swine
Fever
Indirect
antibody
ELISA
(ID.vet,
Grabels,
France)
allows
a
protocol
for
dried
blood
on
filter
papers.
We
used
this
protocol
to
test
the
swab
fragments.
The
original
protocol
foresees
the
use
of
two
filter
paper
punches
with
a
diameter
of
6
mm.
We
replaced
them
with
two
of
the
above-
mentioned
Genotube
fragments
and
performed
all
subse-
quent
steps
according
to
the
manufacturer's
instructions.
Based
on
the
above-mentioned
set
of
samples,
we
could
clearly
demonstrate
that
antibody
detection
is
possible
also
from
Genotube
swabs
(see
Table
1).
Fourty
out
of
42
samples
were
in
complete
agreement
with
the
serological
status,
and
an
additional
sample
that
had
a
doubtful
status
was
detected
positive.
Only
one
doubtful
sample
gave
a
negative
result.
Comparison
of
dried
blood
on
filter
paper
and
on
Genotube
swabs
gave
similar
results
(see
Table
1),
also
in
terms
of
raw
data
values
(data
not
shown).
No
false
positive
reactions
occurred,
even
with
samples
stored
for
several
months
(see
Table
1).
Despite
the
fact,
that
further
validation
is
clearly
needed
and
ongoing,
these
initial
results
are
most
promising
and
could
prompt
the
inclusion
of
antibody
detection
from
swabs
in
the
field.
Due
to
the
very
high
virulence
of
the
ASFV
strains
currently
circulating
in
Eastern
Europe
(Gabriel
et
al.,
2012;
Blome
et
al.,
2013),
antibody
detection
is
still
a
rather
rare
finding.
However,
to
obtain
a
full
picture
of
the
epidemiological
situation,
and
to
fulfil
all
legal
requirements
(e.g.
Commission
Decision
2003/422/EC),
the
search
for
antibodies
is
mandatory.
Another
important
issue
would
be
to
isolate
the
causative
virus
strains
for
further
characterization.
In
this
respect,
608
Letter
to
the
Editor/Veterinary
Microbiology
174
(2014)
607-608
Table
1
EDTA
blood
sample
details
and
results.
The
status
of
the
sample
was
defined
by
a
p72
antibody
EUSA
(Ingezim
PPA
Compac,
Ingenasa)
of
the
corresponding
serum
sample.
The
storage
time
is
depicted
in
month
(M).
DPI
=
days
post
inoculation;
neg
=
negative
according
to
the
test
criteria;
dbt
=
doubtful
according
to
the
test
criteria;
pos
=
positive
according
to
the
test
criteria;
nd
=
not
done;
inact.
=
inactivated.
Genotube
Animal
ID
DPI
Storage
Virus
Status
Result
swab
Result
filter
1
HS1
0
21
M
neg neg
nd
2
HS2
0
21
M
neg neg
nd
3
HS3
0
21
M
neg neg
nd
4
HS4
0
21
M
neg neg
nd
5
HS5
0
21
M
neg neg
nd
6
HS6
0
21
M
neg neg
nd
7
HS7
0
21
M
neg neg
nd
8
HS8
0
21
M
neg neg
nd
9
HS9
0
21
M
neg neg
nd
10
HS11
0
21
M
neg neg
nd
11
HS12
0
21
M
neg neg
nd
12
HS13
0
21
M
neg neg
nd
13
HS3
28
21
M
Armenia08
inact.
neg neg
nd
14
HS4
28
21
M
Armenia08
inact.
neg neg
nd
15
HS6
28
21
M
Armenia08
inact.
neg neg
nd
16
HS7
28
21
M
Armenia08
inact.
pos
pos
nd
17
HS8
28
21
M
Armenia08
inact.
pos
pos
nd
18
HS9
28
21
M
Armenia08
inact.
pos
pos
nd
19
HS11
28
21
M
Armenia08
inact.
pos
pos
nd
20
HS8
35
21
M
Armenia08
inact.
pos
pos
nd
21
HS12
28
21
M
Armenia08
inact.
pos
pos
nd
22
HS13
28
21
M
Armenia08
inact.
pos
pos
nd
23
HS4
41
21
M
Armenia08
inact.
dbt
neg
nd
24
HS6
41
21
M
Armenia08
inact.
dbt
pos
nd
25
HS7
41
21
M
Armenia08
inact.
pos
pos
nd
26
HS8
41
21
M
Armenia08
inact.
pos
pos
nd
27
HS9
41
21
M
Armenia08
inact.
pos
pos
nd
28
HS11
41
21
M
Armenia08
inact.
pos
pos
nd
29
HS12
41
21
M
Armenia08
inact.
pos
pos
pos
30
HS13
41
21
M
Armenia08
inact.
pos
pos
pos
31
HS1
29
1M
OURT88/3
pos
pos
pos
32
HS2
29
1M
OURT88/3
pos
pos
pos
33
HS3
29
1M
OURT88/3
pos
pos
pos
34
HS4
29
1M
OURT88/3
pos
pos
pos
35
HS5
29
1M
OURT88/3
pos
pos
pos
36
HS6
29
1M
OURT88/3
pos
pos
pos
37
HS7
29
1M
OURT88/3
pos
pos
pos
38
HS8
29
1M
OURT88/3
pos
pos
pos
39
HS9
29
1M
OURT88/3
pos
pos
pos
40
HS1
0
29
1M
OURT88/3
pos
pos
pos
41
HS1
0
1M
neg neg neg
42
HS2
0
1M
neg neg neg
preliminary
studies
showed
that
ASFV
isolation
from
Genotube
swabs
was
possible
in
blood
monocyte
derived
macrophage
cultures
while
CSFV
could
not
be
isolated
(data
not
shown).
Probably,
the
latter
could
be
obtained
from
RNA
transfection.
Easy
sampling
and
testing
by
using
swabs
for
both
pathogen
and
antibodies
could
facilitate
this
task
and
present
a
pragmatic
approach
also
for
other
scenarios,
e.g.
for
wild-life
monitoring
in
Africa.
References
Blome,
S.,
Gabriel,
C.,
Beer,
M.,
2014.
Modern
adjuvants
do
not
enhance
the
efficacy
of
an
inactivated
African
swine
fever
virus
vaccine
preparation.
Vaccine
32
(June
(31)),
3879-3882.
Blome,
S.,
Gabriel,
C.,
Dietze,
K.,
Breithaupt,
A.,
Beer,
M.,
2012.
High
virulence
of
African
swine
fever
virus
caucasus
isolate
in
European
wild
boars
of
all
ages.
Emerg.
Infect.
Dis.
18,
708.
Gabriel,
C.,
Blome,
S.,
Malogolovkin,
A.,
Parilov,
S.,
Kolbasov,
D.,
Teifke,
J.P.,
Beer,
M.,
2011.
Characterization
of
African
swine
fever
virus
caucasus
isolate
in
European
wild
boars.
Emerg.
Infect.
Dis.
17,
2342-2345.
Petrov,
A.,
Schotte,
U.,
Pietschmann,
J.,
Drnger,
C.,
Beer,
M.,
Goller,
K.V.,
Blome,
S.,
2014.
Alternative
sampling
strategies
for
passive
classical
and
African
swine
fever
surveillance
in
wild
boar.
Vet.
Microbiol.
http://dx.doi.org/10.1016/j.vetmic.2014.07.030.
Sandra
Blome•
Katja
V.
Goller
Anja
Petrov
Carolin
Drager
Jana
Pietschmann
Martin
Beer
Institute
of
Diagnostic
Virology,
Friedrich-Loeffler-Institut,
Suedufer
10,
17493
Greifswald
-
Insel
Riems,
Germany
Corresponding
author.
Tel.:
+49
38351
71144;
fax:
+49
38351
71275
E-mail
address:
30
August
2014