Vaccination protocol and bacterial strain affect the serological response of beef calves against blackleg


Araujo, R.F.; Curci, V.C.L.M.; Nobrega, F.L.C.; Ferreira, R.M.M.; Dutra, I.S.

Pesquisa Veterinária Brasileira 30(7): 554-558

2008


The serological response of beef calves was evaluated with different vaccination regimens against blackleg, using an official strain (MT) and a field-collected strain of Clostridium chauvoei as antigens. Sixty calves were randomly allocated to four different groups and were submitted to distinct vaccination protocols with a commercial polyvalent vaccine. Group G1 was first vaccinated at four months of age and a booster shot was given after weaning, at eight months. Group G2 was given the first dose at eight months and a booster shot 30 days later. Group G3 was vaccinated only once at eight months and the control group was not vaccinated. These alternative vaccination regimens were proposed in an effort to adequately protect cattle under open-field farming conditions. Serological evaluations were made by Elisa at 4, 8, 9 and 10 months of age. Both groups receiving booster shots had a significantly increased serological response 30 days later. However, the serum IgG levels against C. chauvoei were significantly higher in the calves that were first vaccinated at four months. At 10 months, the two booster shot groups (G1 and G2) had similar serological responses, while the calves that were treated with a single dose of vaccine at weaning (G3) had a response that was similar to that of the control group. The serological response of the calves was significantly inferior at several of the evaluation times when the field strain of the bacteria was used as a challenge antigen instead of the official MT strain. The serological response of calves that are vaccinated twice was found to be satisfactory, independent of the first injection being made at four or eight months of age. It was also concluded that it would be useful to include local bacterial strains in commercial vaccine production.

1
Received
on
January
11,
2010.
influenciam
na
resposta
sorologica
contra
o
carlAnculo
Accepted
for
publication
on
March
19,
2010.
sintomatico
em
bezerros
de
corte.]
Foi
avaliada
a
resposta
2
Programa
de
Pos-Graduagdo
em
Medicina
Veterinaria,
Area
de
Medicina
Veterinaria
Preventiva,
Faculdade
de
Ciencias
Agrarias
e
sorologica
de
bezerros
de
corte
submetidos
a
diferentes
es-
Veterinarias,
Universidade
Estadual
Paulista
(Unesp),
Campus
quemas
de
vacinacao
contra
o
carb6nculo
sintornatico,
em-
Jaboticabal,
Via
de
Acesso
Prof.
Paulo
Donato
Castellane
s/n,
pregando-se
como
antfgenos
duas
cepas
distintas
de
Jaboticabal,
SP
14884-900,
Brazil.
E-mail:
Clostridium
chauvoei:
uma
oficial
(MD
e
a
outra
uma
cepa
de
3
Unidade
de
Pesquisa
e
Desenvolvimento
de
Aragatuba,
Agenda
Paulista
de
Tecnologia
dos
Agronegocios
(APTA),
Av. Alcides
campo.
Os
animais
(n=60)
foram
randomizados
em
quatro
Fagundes
Chagas
122,
Aragatuba,
SP
15055-565,
Brazil.
grupos
(G1,
G2,
G3
e
Controle)
e
submetidos
a
tits
protoco-
4
Centro
de
Pesquisa
e
Desenvolvimento
de
Imunobiologicos
Vete-
los
distintos
de
vacinacao
com
um
produto
comercial
poliva-
rinarios,
Instituto
Butantan,
Av.
Vital
Brasil
1500,
Sao
Paulo,
SP
05503-
lente.
0
G1
foi
primovacinado
aos
4
meses
de
idade
e
rece-
900,
Brazil.
beu
o
reforgo
ap6s
desmama
(8
meses
de
idade).
0
G2
rece-
Departamento
de
Apoio,
Producao
e
Saude
Animal,
Curso
de
Me-
dicina
Veterinaria,
Unesp,
Rua
Clovis
Pestana
793,
Bloco
37,
Aragatuba,
beu
a
primeira
dose
aos
8
meses
de
idade
e
reforgo
30
dias
SP
16050-680.
*Corresponding
author:
ap6s.
0
G3
foi
vacinado
somente
aos
8
meses
de
idade
e
o
ABSTRACT.-
Araujo
R.F.,
Curci
V.C.L.M.,
Nobrega
F.L.C.,
Ferreira
R.M.M.
&
Dutra
I.S.
2010.
Vaccination
protocol
and
bacterial
strain
affect
the
serological
response
of
beef
calves
against
blackleg.
Pesquisa
Veterinaria
Brasileira
30(7):554-558.
Departamento
de
Apoio,
Producao
e
Sa6de
Animal,
Curso
de
Medicina
Veterinaria,
Universidade
Estadual
Paulista,
Rua
Clovis
Pestana
793,
Bloco
37,
Aragatuba,
SP
16050-680,
Brazil.
E-mail:
The
serological
response
of
beef
calves
was
evaluated
with
different
vaccination
regimens
against
blackleg,
using
an
official
strain
(MT)
and
a
field-collected
strain
of
Clostridium
chauvoei
as
antigens.
Sixty
calves
were
randomly
allocated
to
four
different
groups
and
were
submitted
to
distinct
vaccination
protocols
with
a
commercial
polyvalent
vaccine.
Group
G1
was
first
vaccinated
at
four
months
of
age
and
a
booster
shot
was
given
after
weaning,
at
eight
months.
Group
G2
was
given
the
first
dose
at
eight
months
and
a
booster
shot
30
days
later.
Group
G3
was
vaccinated
only
once
at
eight
months
and
the
control
group
was
not
vaccinated.
These
alternative
vaccination
regimens
were
proposed
in
an
effort
to
adequately
protect
cattle
under
open-field
farming
conditions.
Serological
evaluations
were
made
by
Elisa
at
4,
8,
9
and
10
months
of
age.
Both
groups
receiving
booster
shots
had
a
significantly
increased
serological
response
30
days
later.
However,
the
serum
IgG
levels
against
C.
chauvoei
were
significantly
higher
in
the
calves
that
were
first
vaccinated
at
four
months.
At
10
months,
the
two
booster
shot
groups
(G1
and
G2)
had
similar
serological
responses,
while
the
calves
that
were
treated
with
a
single
dose
of
vaccine
at
weaning
(G3)
had
a
response
that
was
similar
to
that
of
the
control
group.
The
serological
response
of
the
calves
was
significantly
inferior
at
several
of
the
evaluation
times
when
the
field
strain
of
the
bacteria
was
used
as
a
challenge
antigen
instead
of
the
official
MT
strain.
The
serological
response
of
calves
that
are
vaccinated
twice
was
found
to
be
satisfactory,
independent
of
the
first
injection
being
made
at
four
or
eight
months
of
age.
It
was
also
concluded
that
it
would
be
useful
to
include
local
bacterial
strains
in
commercial
vaccine
production.
INDEX
TERMS:
Clostridiosis,
Clostridium
chauvoei,
vaccine,
antibody,
beef
cattle.
RESUMO.-
[Esquemas
de
vacinagdo
e
cepa
bacteriana
Pesq.
Vet.
Bras.
30(7):554-558,
julho
2010
Vaccination
protocol
and
bacterial
strain
affect
the
serological
response
of
beef
calves
against
blackleg'
Rafael
F.
Araujo
2
,
Vera
C.L.M.
Curci
3
,
Fabiana
L.C.
Nobrega
4
,
Rosa
M.M.
Ferreira
5
and
Iveraldo
S.
Dutra
5
*
554
Vaccination
protocol
and
bacterial
strain
affect
the
serological
response
of
beef
calves
against
blackleg
555
Controle
nao
foi
vacinado.
As
avaliagaes
sorologicas
pelo
ensaio
imunoenzimatico
(Elisa)
foram
realizadas
aos
4,
8,
9
e
10
meses
de
idade
dos
bezerros.
Nos
dois
esquemas
em
que
os
animais
receberam
o
booster
(G1
e
G2),
houve
um
aumento
significativo
(p<0,05)
da
resposta
sorologica
quan-
do
foram
avaliados
30
dias
apos.
No
entanto,
os
valores
sericos
de
IgG
contra
C.
chauvoei
foram
significativamente
maiores
nos
animais
primovacinados
aos
4
meses
de
idade.
Aos
10
meses,
os
dois
grupos
que
receberam
o
reforgo
vacinai
(G1
e
G2)
nao
diferiram
entre
si
na
resposta
sorologica
e
os
bezerros
que
receberam
uma
Unica
dose
de
vacina
na
des-
mama
(G3)
nao
diferiu
do
Controle.
A
resposta
sorologica
dos
bezerros
foi
significativamente
inferior
(p<0,05)
em
diver-
sos
momentos
da
avaliagao,
quando
a
cepa
de
campo
foi
empregada
como
antigen°
e
quando
comparada
a
da
cepa
MT.
Pode-se
deduzir
que
a
resposta
sorologica
dos
bezerros
vacinados
aos
4
e
8
meses
de
idade
foi
satisfatoria
e
que
existiram
diferengas
significativas
nos
valores
sericos
de
anticorpos
contra
C.
chauvoei
quando
na
avaliagao
foi
em-
pregada
cepa
de
campo.
TERMOS
DE
INDEXACAO:
Clostridiose,
Clostridium
chauvoei,
vacina,
anticorpos,
bovinos
de
code.
INTRODUCTION
Blackleg
is
a
necrotizing
myositis
that
is
caused
by
the
activation
of
latent
spores
of
Clostridium
chauvoei
in
the
muscles
of
bovines.
This
clostridiosis
is
a
wide-spread
sanitary
problem
that
has
the
potential
to
cause
serious
economic
losses.
This
disease
mainly
affects
6
to
30-month
old
bovines,
when
there
apparently
is
a
reduction
in
antibody
levels,
making
the
animals
susceptible
to
this
disease
(Kriek
&
Odendaal
2004).
Immunization
against
blackleg
is
one
of
the
most
important
prophylactic
measures
for
cattle
rearing
throughout
the
world
and
has
been
used
since
the
19th
century
(Blobel
&
Schliesser
1980).
Though
vaccination
is
done
voluntarily,
cattle
producers
recognize
the
importance
of
this
preventative
measure.
In
Brazil,
according
to
current
data
provided
by
the
National
Syndicate
of
the
Production
of
Animal
Products
(Sindan),
about
150
million
doses
of
vaccine
are
sold
per
year;
these
include
monovalent
and
polyvalent
formulations,
all
containing
C.
chauvoei.
Since
the
1980s,
the
Ministry
of
Agriculture,
Livestock
and
Food
Supply
(MAPA)
has
evaluated
commercial
lots
of
vaccine
against
blackleg,
determining
their
efficiency
in
tests
made
with
guinea
pigs
challenged
with
a
lineage
of
C.
chauvoeidenominated
MT
(Brasil
1997).
During
this
period,
substantial
changes
have
been
made
in
the
formulation
of
commercial
vaccines
against
blackleg,
evolving
from
monovalent
imunogens
produced
in
the
country,
to
complex
polyvalent
formulations,
in
order
to
protect
against
various
clostridioses
and
multiple
species,
with
importation
of
part
of
the
vaccine
material.
The
prescription
for
the
use
of
these
commercial
bacterins
and
polyvalent
toxoids
in
this
country
indicates
a
need
for
a
booster
shot
30
days
after
the
first
injection
(Sindan
2010).
However,
operational
difficulties
in
the
open-field
beef
cattle
rearing
system
used
in
Brazil
makes
it
difficult
to
apply
the
recommended
booster
shots.
Consequently,
it
is
common
practice
in
the
southeastern
and
central
west
regions
of
the
country
to
apply
a
single
vaccination
dose
at
weaning
(eight
months
of
age).
There
is
very
little
information
available
concerning
the
serological
response
of
cattle
against
C.
chauvoei
stimulated
by
vaccination;
that
and
the
increasing
production
and
use
of
complex polyvalent
vaccines,
the
need
to
objectively
understand
the
normal
vaccine
protocols
and
the
economic
importance
of
blackleg,
prompted
us
to
evaluate
the
serological
response
of
beef
calves
submitted
to
different
vaccination
regimens
against
blackleg.
A
commercial
polyvalent
vaccine
was
used,
with
two
different
bacterial
strains
as
antigens.
MATERIALS
AND
METHODS
Vaccine.
The
calves
were
vaccinated
with
an
imported
polyvalent
vaccine
that
is
approved
by
the
Ministry
of
Agriculture,
Livestock
and
Food
Supply
(MAPA).
This
vaccine against
blackleg
contained,
along
with
Clostridium
chauvoei,
bacterins
and
toxoids
of
other
clostridia!
bacteria
(aluminum
hydroxide
adjuvant);
it
was
stored
in
a
refrigerator
and
applied
according
to
the
manufacturer's
instructions
in
aliquots
of
5m1,
or
according
to
the
research
protocol.
Vaccination
and
serological
evaluation
schemes.
Serological
evaluations
were
made
of
60
mixed
breed
calves
(Nelore,
Aberdeen
Angus,
Brahman
and
Red
Angus),
born
during
the
first
20
days
of
June
2007,
the
mothers
of
which
were
multiparous
Nelore
cattle
that
had
been
submitted
to
the
normal
sanitary
management
of
the
farm,
which
consisted
of
two
annual
vaccinations
against
blackleg
(May
and
November).
The
calves
that
were
to
be
immunized
were
randomly
divided
into
three
groups
(n
=15
each)
and
were
submitted
to
one
of
three
different
vaccination
regimens.
Group
1
(G1)
was
vaccinated
at
four
months
and
a
booster
shot
was
given
at
weaning
(8
months).
Group
2
(G2)
was
first
vaccinated
at
weaning
and
received
the
booster
shot
30
days
later.
Group
3
was
vaccinated
with
a
single
dose
of
the
vaccine
at
weaning.
The
control
group
(n=15)
was
not
vaccinated.
The
blood
samples
were
collected
from
the
external
jugular
vein
with
Vacutainer®
tubes,
which
were
maintained
at
room
temperature
until
complete
retraction
of
the
coagulum.
They
were
then
centrifuged
to
obtain
the
serum,
which
was
maintained
in
a
freezer
(-20°C)
until
the
serological
tests.
The
serum
collections
were
made
at
4,
8,
9
and
10
months
of
age.
Clostridium
chauvoei
strains.
The
serological
evaluation
was
made
with
antigens
that
consisted
of
two
different
strains
of
C.
chauvoei:
the
reference
strain,
denominated
MT
and
a
field
isolate
that
came
from
a
disease
epidemic
associated
with
vaccine
failure
(Santos
2003).
The
reference
strain
(MT)
was
supplied
by
MAPA.
The
natural
epidemic
isolate
was
identified
by
PCR
and
maintained
in
the
bacterial
library
of
the
Infectious
Diseases Laboratory
of
the
Department
of
Animal
Production,
Health,
and
Husbandry,
Aragatuba
Campus
of
Unesp.
lmmunoenzymatic
test
(Elise).
The
positive
serum
used
to
standardize
the
serological
test
was
obtained
from
two
18-month-
old
bovines
that
had
been
immunized
with
three
doses
of
commercial
polyvalent
vaccine
against
clostridioses,
with
a
15-
day
interval
between
vaccinations.
The
negative
serum
sample
used
in
the
Elisa
test
was
obtained
from
a
new-born
calf,
before
it
had
fed
on
colostrum.
The
antigens
from
the
reference
strain
(MT)
and
from
the
field-collected
strain
were
standardized
as
recommended
by
Crichton
et
al.
(1990).
The
96-hole
microplates
(Nunc®)
were
sensitized
with
100µ1/
well
of
antigen
diluted
in
carbonate-bicarbonate
buffer,
diluted
Pesq.
Vet.
Bras.
30(7):554-558,
julho
2010
556
Rafael
F.
Araujo
et
al.
1:50,
and
incubated
in
a
humid
chamber
for
12
hours
at
4°C.
Soon
after
this
step,
the
plates
were
submitted
to
three
rinses
with
0.05%
PBS
Tween
(PBS-T)
in
an
automatic
pipette
washer.
The
reaction
was
then
blocked
with
200µ1/well
of
reconstituted
10%
powdered
milk
(Molico®)
diluted
in
the
carbonate-
bicarbonate
buffer.
The
plates
were
then
incubated
in
a
humid
chamber
at
37°C
for
45
minutes,
and
submitted
to
the
rinse
cycle.
Then
100µI
of
the
test
and
control
sera
diluted
1:100
in
PBS
+
10%
powdered
milk.
Two
wells
were
left
without
sera;
only
the
buffer
was
added.
This
was
the
plate
control
(blank).
After
this
step,
the
plates
were
incubated
at
37°C
for
60
minutes,
and
they
were
then
run
through
the
rinse
cycle.
Then,
100µI
of
commercial
immunoenzyme
conjugate
SIGMA®)
was
added
to
each
well
(this
consisted
of
anti-bovine
IgG
rabbit
serum
conjugated
with
peroxidase,
diluted
1:10,000
in
PBS
+
10%
powdered
milk);
the
plates
were
incubated
at
37°C
for
90
minutes
and
were
again
rinsed
three
times.
Immediately
afterward,
50µI
of
ortho-phenylenediamine
substrate,
diluted
in
citrate-phosphate
buffer,
was
added.
The
reaction
was
interrupted
after
15
minutes
with
2
M
HCI
(50
µl/well),
and
the
readings
made
with
a
microplate
spectrophotometer
(Labsystem
-
Multiskan
EX®),
with
a
492nm
filter.
Statistical
analysis.
The
Elisa
data
was
transformed
by
log
(x+1)
and
submitted
to
analysis
of
variance
with
repeated
measures
and
residual
analysis
to
check
for
normality
and
homogeneity
of
the
variance,
which
are
prerequisites
for
analysis
of
variance.
The
means
were
compared
with
the
Tukey
test
and
the
differences
were
considered
significant
when
p<0.05.
The
statistical
analyses
were
made
with
the
Statistical
Analysis
System
(SAS
1999).
RESULTS
The
three
vaccination
regimens
significantly
(p<0.05)
increased
the
serum
antibody
levels
soon
after
the
initial
vaccination
and
after
the
booster
shot
(Table
1,
Fig.1-2).
The
mean
serum
antibody
levels
in
the
calves
first
vaccinated
at
four
months
of
age
(G1)
did
not
differ
from
the
control
group,
when
evaluated
at
eight
months.
In
this
same
group,
when
the
booster
shot
was
given
at
eight
months,
there
was
a
significant
increase
in
serum
antibody
levels
after
30
days,
p
1$
-
2
1.4
1,2
-
1,0
0,8
-
C
E.
0,8
-
"6
0,4
0,2
-
C
0,0
4
8
9
10
Months
OG1
1G2
t
G3
MControl
Fig.1.
Serological
response
of
calves
induced
by
a
commercial
imported
polyvalent
vaccine
against
clostridiosis,
expressed
in
optical
density
units
(OD)
in
an
Elisa
test
using
a
reference
(MT)
strain
of
Clostridium
chauvoei,
and
three
different
vaccination
regimens
(G1,
G2
and
G3).
1,4
,
1,2
"E=1,0
0,8
72
0
'
6
u_
O
0
.
4
0
0,2
0,0
4
8
9
10
Months
IDGI
II
G2
OG3
MControl
Fig.2.
Serological
response
of
calves
induced
by
a
commercial
imported
polyvalent
vaccine
against
clostridiosis,
expressed
in
optical
density
units
(OD)
in
an
Elisa
test
using
a
field-
collected
strain
of
Clostridium
chauvoei,
and
three
different
vaccination
regimens
(G1,
G2
and
G3).
different
from
what
was
found
for
the
other
two
groups
(G2
and
G3)
that
were
evaluated
at
nine
months.
In
the
evaluation
Table
1.
Mean values
2
standard
deviation
of
the
serological
response
of
calves
vaccinated
with
commercial
imported
polyvalent
vaccine
against
clostridiosis,
expressed
in
optical
density
units
(OD)
in
an
Elise
test
using
reference
(MT)
and
field-collected
strains
of
Clostridium
chauvoei,
using
three
different
vaccination
regimens
(G1,
G2
and
G3)
Strain
Group
Age
of
the
calves
(months)
4
8
9
10
MT
G1
0.424
±
0.227
aB
0.256
±
0.133
abB*
1.045
±
0.336
aA*
0.830
±
0.275
aA*
G2
0.289
±
0.161
abC
0.101
±
0.060
bD*
0.504
±
0.183
bB
0.986
±
0.310
aA
G3
0.299
±
0.156
abAB
0.240
±
0.193
abB*
0.447
±
0.231
bA
0.325
±
0.169
bAB
Control
0.178
±
0.082
bB
0.386
±
0.325
aA*
0.203
±
0.132
cB*
0.266
±
0.125
bAB*
Field
G1
0.401
±
0.237
aB
0.356
±
0.146
aB
0.865
±
0.307
aA
0.772
±
0.254
aA
G2
0.282
±
0.141
abC
0.140
±
0.088
bC
0.497
±
0.193
bB
0.970
±
0.296
aA
G3
0.314
±
0.141
abA
0.171
±
0.141
bB
0.427
±
0.210
bA
0.318
±
0.126
bA
Control
0.192
±
0.068
bA
0.230
±
0.185
abA
0.179
±
0.139
cA
0.231
±
0.112
bA
Means
followed
by
different
letters
(lower
case
in
the
column
and
upper
case
in
the
row)
are
significantly
different
(Tukey
test,
p<0.05).
*
Significantly
different
from
the
field-collected
strain
(p<0.05).
G1
=
vaccinated
at
4
and
8
months;
G2
=
vaccinated
at
eight
and
nine
months;
G3
=
vaccinated
at
eight
months;
Control
=
not
vaccinated.
Pesq.
Vet.
Bras.
30(7):554-558,
julho
2010
Vaccination
protocol
and
bacterial
strain
affect
the
serological
response
of
beef
calves
against
blackleg
557
of
the
serological
response
at
10
months,
no
difference
was
observed
between
calves
vaccinated
at
four
and
eight
months
(G1)
and
those
that
were
vaccinated
at
eight
months
and
given
a
booster
shot
30
days
later
(G2).
The
mean
serum
antibody
levels
in
calves
first
vaccinated
at
eight
months
of
age
and
given
a
booster
shot
30
days
later
(G2),
did
not
differ
from
those
in
calves
vaccinated
only
at
eight
months
(G3),
when
they
were
evaluated
at
nine
months.
This
same
group
had
significantly
higher
serum
antibody
levels
when
evaluated
30
days
later,
though
at
10
months
they
did
not
differ
from
the
control
group
(Table
1,
Fig.1-2).
When
the
serological
test
was
done
using
the
field-collected
strain
of
C.
chauvoei,
the
mean
serum
antibody
values
were
significantly
lower
at
two
evaluation
times
among
calves
first
vaccinated
at
four
months
and
given
a
booster
shot
at
eight
months
(G1);
this
was
also
found
at
one
evaluation
time
only
among
calves
that
had
only
been
vaccinated
at
eight
months
(G3),
and
at
three
evaluation
times
among
the
control
calves.
When
the
reference
strain
(MD
was
used,
the
mean
serum
levels
were
significantly
lower
at
one
evaluation
time
among
calves
that
were
first
vaccinated
at
four
months
and
given
a
booster
shot
at
eight
months
(G1);
and
also
at
one
evaluation
time
among
calves
that
were
vaccinated
at
eight
months
and
had
a
booster
shot
30
days
later
(G2,
Table
1).
DISCUSSION
Vaccination
is
the
principal
prophylactic
measure
used
to
avoid
bovine
mortality
caused
by
Clostridium
chauvoei.
Though
it
is
not
obligatory,
the
benefits
of
immunization
against
blackleg
are
widely
known
by
technical
personnel
and
by
rural
producers.
According
to
Kriek
&
Odendaal
(2004),
vaccination
of
bovines
can
be
done
from
four-months
of
age
on,
with
a
booster
shot
30
days
later,
followed
by
annual
vaccination,
which
guarantees
protection
until
three
years
of
age.
In
Brazil,
commercial
products
that
contain
C.
chauvoei
are
analyzed
by
MAPA
since
the
1980s,
through
testing
in
guinea
pigs.
Only
vaccines
that
protect
at
least
seven
of
eight
vaccinated
guinea
pigs
are
approved
for
commercialization
(Brasil
1997).
In
this
context,
the
general
perception
is
that
the
vaccines
used
to
control
blackleg
effectively
contribute
to
prophylaxis
against
this
disease.
However,
various
important
aspects
related
to
what
actually
happens
in
the
field,
and
how
the
commercial
products
are
formulated,
remain
unknown
or
poorly
studied.
Bacterins
from
C.
chauvoei
evaluated
as
excellent,
mar-
ginal
or
weak
in
the
test
for
potency
using
guinea
pigs
protect
as
well
or
better
in
bovines
subjected
to
an
experimental
challenge
(Macheak
et
al.
1972).
Though
the
challenge
tests
are
more
adequate
for
vaccine
quality
control,
there
is
a
correlation
between
the
agglutinating
antibody
titers
and
the
protective
immunity
in
animals
against
a
bacterial
challenge
(Claus
&
Macheak
1972);
the
concordance
between
the
agglutination
tests
and
the
Elisa
test
for
measuring
the
serological
response
in
bovines
vaccinated
against
blackleg
is
greater
than
90%
(Araujo
2009).
Elisa
has
also
proved
to
be
an
appropriate
tool
for
determining
the
potential
of
vaccines
that
contain
C.
chauvoei
antigens
(Crichton
et
al.
1990).
Based
on
the
serological
response
of
the
calves
vaccinated
with
the
commercial
polyvalent
vaccine,
it
can
be
seen
that
an
initial
vaccination
at
four
months
and
a
booster
shot
at
weaning
(Table
1)
is
equivalent
to
the
vaccination
scheme
indicated
by
the
company
that
makes
the
vaccines
and
is
significantly
superior
to
what
is
being
used
in
the
field.
In
an
initial
analysis,
besides
facilitating
sanitary
management
in
open
field
cattle
rearing,
and
the
fact
that
this
is
new
information
concerning
refrigerated
vaccines,
this
vaccination
regimen
(G1)
was
found
to
be
superior
when
evaluated
30
days
after
the
booster
(Fig.1-2).
Even
though
the
minimum
concentration
of
antibodies
necessary
to
protect
the
animals
against
natural
challenges
by
C.
chauvoei
is
unknown,
these
levels
could
be
sufficient
to
provide
adequate
immunity
for
the
herd
under
normal
conditions,
during
this
period
of
greater
susceptibility
to
disease.
However,
it
will
be
necessary
to
determine
how
the
immune
response
develops
at
later
ages,
as
well
as
the
epidemiological
behavior
of
this
disease
under
field
challenge
situations,
conditions
that
were
not
included
in
this
study.
The
serological
response
to
a
field-strain
antigen
was
measured
because
previous
tests
had
shown
different
degrees
of
protection
in
guinea
pigs
vaccinated
with
different
commercial
products.
Santos
(2003)
reported
that
21
of
22
vaccine
lots
provided
immune
protection
to
guinea
pigs
challenged
with
MT
strain;
when
the
challenge
was
made
with
a
field-strain
antigen,
only
eight
of
the
22
had
adequate
protection
levels.
There
were
also
differences
in
the
serological
response
of
animals
challenged
with
this
same
field
strain
in
this
research
(Table
1).
This
is
important
information
for
vaccine
producers
and
for
government
agencies
that
regulate
the
commerciali-
zation
of
these
vaccines
in
this
country.
The
complex
antigenic
composition
of
C.
chauvoei,
combined
with
a
lack
of
information
concerning
which
bacterial
strains
are
used
for
producing
the
commercial
vaccines,
make
it
difficult
to
objectively
evaluate
these
products,
which
according
to
Mayr
et
al.
(1984)
should
be
made
with
local
bacterial
strains
in
order
to
guarantee
their
efficacy.
It
is
understood
that
protective
immunity
against
C.
chauvoei
is
mainly
antibacterial
and
to
a
lesser
extent
antitoxic;
however,
it
is
unknown
to
what
extent
each
type
of
immunity
is
stimulated
by
the
vaccinations
(Chandler
&
Gulasekharam
1970,
Crichton
et
al.
1990).
Immunologically,
it
is
unknown
which
factor
actually
confers
better
protection
against
the
extremely
varied
challenges
and
whether
these
antigenic
factors
could
be
used
as
immunogens.
In
fact,
the
vaccines
used
against
blackleg
are
bacterins
and
they
contain
antigens
from
the
whole
culture
material
of
the
microorganism
(Stevenson
&
Stonger
1980).
These
particularities
of
this
bacterium
could
be
reasons
for
the
diverse
results
when
they
are
evaluated
with
distinct
bacterial
strains,
both
in
the
challenge
test
and
when
the
serological
response
is
evaluated.
Among
the
relevant
factors
in
the
development
of
immunity
against
C.
chauvoei,
the
most
important
is
protection
provided
by
vaccines
made
from
strains
that
are
homologous
to
those
in
the
local
environment
(Schipper
et
al.
1978).
Vaccination
with
homologous
strains
gives
better
protection
against
a
Pesq.
Vet.
Bras.
30(7):554-558,
julho
2010
558
Rafael
F.
Araujo
et
al.
homologous
challenge
than
against
a
heterologous
challenge,
though
some
strains
produce
immunity
with
a
wider
spectrum
of
protection
than
do
others
(Kerry
1967).
Consequently,
it
appears
that
the
antigenic
identity
of
the
bacterial
strain
used
to
produce
the
polyvalent
vaccine
used
in
this
research
was
similar
to
that
of
strain
MT.
However,
at
some
evaluation
ti-
mes,
the
serological
response
to
the
field
strain
was
inferior,
which
could
be
decisive
in
cases
of
intense
bacterial
challenge
by
local
strains.
Along
this
line
of
reasoning,
it
would
appear
that
the
ideal
situation
would be
introduction
of
regional
field
strains
for
the
production
of
commercial
products,
along
with
improved
epidemiological
vigilance,
as
proposed
by
Chandler
(1976).
In
Australia,
this
strategy
has
been
used
since
the
1970s,
after
heavy
cattle
losses,
probably
due
to
vaccine
failure
(Reed
&
Reynolds
1977).
Also,
it
would
be
useful
to
implement
systems
for
early
reporting
of
disease
outbreaks,
including
information
about
the
field
strains
of
C.
chauvoei
that
are
involved
(Dodson
1978).
The
substantial
and
complex
changes
in
the
formulations
of
the
vaccines
against
blackleg,
not
always
following
a
technical
rationality,
can
generate
high-risk
situations
in
disease
prophylaxis.
Consequently,
it
is
important
to
be
sure
that
the
immunogenicity
of
C.
chauvoei
in
complex
polyvalent
vaccines
is
sufficient
not
only
for
official
tests,
but
that
they
also
protect
the
animals
against
field
strains.
Vaccinating
calves
at
four
and
eight
months
gave
a
satisfactory
serological
response.
However,
the
efficiency
of
this
response
was
significantly
compromised
when
a
field
strain
of
the
bacteria
was
used
as
a
test
antigen.
Acknowledgements.-
To
Professors
Tereza
Cristina
Cardoso
and
Silvia
Helena
Venturoli
Perri,
along
with
technicians
Addo
Angelo
Cus-
t6dio,
Gilmara
Castilho
and
Alessandra
Mara
Alves
Ragozo,
of
the
Universidade
Estadual
Paulista,
Campus
Aragatuba,
for
helping
collect
sera
and
for
their
help
in
the
laboratory;
to
the
company
Agropecuaria
Estrela
do
Ceu
that
helped
with
the
field
work,
and
also
to
Coordena-
gdo
de
Aperfeigoamento
de
Pessoal
de
Nivel
Superior
(CAPES)
for
a
Master
of
Science
scholarship.
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An
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M.E.
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The
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the
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of
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Biologicals
18:49-54.
Dodson
L.F.
1978.
Failure
of
Clostridium
chauvoei
vaccines
to
protect
against
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Aust.
Vet.
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54:598.
Kerry
J.B.
1967.
Immunological
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between
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of
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Sci.
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Kriek
N.P.J.
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M.W.
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Clostridium
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Coetzer
R.
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(Eds),
Infectious
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2n°
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Oxford
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Macheak
M.E.,
Claus
K.D.
&
Maloy
S.E.
1972.
Potency
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dium
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potency
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Mayr
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der
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in
der
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Reed
G.A.
&
Reynolds
L.
1977.
Failure
of
Clostridium
chauvoei
vaccines
to
protect
against
blackleg.
Aust.
Vet.
J.
53:393.
Santos
B.A.
2003.
Avaliagdo
da
eficacia
em
cobaias
de
imunogenos
contra
carbunculo
sintomatico
em
use
no
Brasil.
Dissertagdo
de
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