ArticlePDF Available

The Immunological Response of Llamas (Lama glama) Following Experimental Infection with Mycobacterium bovis

Authors:

Abstract

Llamas were experimentally infected with Mycobacterium bovis in order to evaluate the axillary skin test and the ELISA as diagnostic procedures for tuberculosis in llamas (Lama glama). Six llamas were given a single intratracheal challenge with 1 of 2 doses of a recent field isolate of M. bovis and 2 llamas were left as noninfected controls. This resulted in a progressive disease in some animals with 1 mortality as early as 68 d post-infection (PI). The tuberculin skin test, at the axillary site, was positive in 4 of 5 infected llamas at 80 d PI. At 143 d PI, all 3 surviving lamas were positive, including the one which had not responded at 80 d PI. The application of skin and serological tests throughout the course of this experiment adds support for the need to further evaluate the skin test and its anamnestic effect on serodiagnosis since serological responses were generally not observed in the absence of skin testing or antibiotic treatment. The wide variation in M. bovis antigens recognized by the serological response would indicate that a diagnostic panel should include multiple antigens such as MPB70 and lipoarabinomannan (LAM). While skin testing or serology alone may be of limited value to diagnose tuberculosis in llamas, together they may offer an enhanced potential for immunodiagnosis of tuberculosis.
The
Immunological
Response
of
Llamas
(Lama
glama)
Following
Experimental
Infection
with
Mycobacterium
bovis
J.B.
Stevens,
C.O.
Thoen,
E.B.
Rohonczy,
S.
Tessaro,
H.A.
Kelly,
and
J.R.
Duncan
ABSTRACT
Llamas
were
experimentally
infected
with
Mycobacterium
bovis
in
order
to
evaluate
the
axillary
skin
test
and
the
ELISA
as
diagnos-
tic
procedures
for
tuberculosis
in
llamas
(Lama
glama).
Six
llamas
were
given
a
single
intratracheal
challenge
with
1
of
2
doses
of
a
recent
field
isolate
of
M.
bovis
and
2
llamas
were
left
as
noninfected
controls.
This
resulted
in
a
progres-
sive
disease
in
some
animals
with
1
mortality
as
early
as
68
d
post-
infection
(PI).
The
tuberculin
skin
test,
at
the
axillary
site,
was
positive
in
4
of
5
infected
llamas
at
80
d
PI.
At
143
d
PI,
all
3
surviving
lamas
were
positive,
including
the
one
which
had
not
responded
at
80
d
PI.
The
application
of
skin
and
serolog-
ical
tests
throughout
the
course
of
this
experiment
adds
support
for
the
need
to
further
evaluate
the
skin
test
and
its
anamnestic
effect
on
serodiagnosis
since
serological
responses
were
generally
not
observed
in
the
absence
of
skin
test-
ing
or
antibiotic
treatment.
The
wide
variation
in
M.
bovis
antigens
recognized
by
the
serological
response
would
indicate
that
a
diag-
nostic
panel
should
include
multiple
antigens
such
as
MPB70
and
lipoarabinomannan
(LAM).
While
skin
testing
or
serology
alone
may
be
of
limited
value
to
diagnose
tuberculosis
in
llamas,
together
they
may
offer
an
enhanced
poten-
tial
for
immunodiagnosis
of
tuberculosis.
RESUME
Des
lamas
ont
ete
inocules
avec
Mycobacterium
bovis
afin
d'valuer
l'epreuve
intradermique
au
site
axillaire
et
l'epreuve
ELISA