Ann. Méd. Vét., 2011, 155 (1), pp 38-52 The host immune response against Neospora caninumGHALMI F.Abstract :
Neospora caninum is an Apicomplexan
heteroxenous parasite
with dog as domestic definitive
host and bovine as intermediate
host. This parasite is responsible
for many abortions in bovine
worldwide. It is an obligate intracellular
parasite which is invasive
since it can reach deep host
organs such as brain, lungs,
liver or spleen. The host immune
response against this pathogen
was essentially studied in mouse
and bovine. This article presents
the most relevant studies performed
on these models and the
vaccine trials tested. It appears
that although the humoral specific
immune response (specific
antibodies) is intense with
seropositive hosts, the cellular
immune response mediated
mainly by gamma interferon
(IFN-γ) is the key of the control to
infection by N. caninum.
This cytokine is produced by
Th1 lymphocytes and inhibits the
Th2 response. If the protection is
efficient in non-pregnant animals
remaining mostly asymptomatic,
the situation is more critical
in pregnant animals. Indeed, in
this case Th1 response is reduced
by Th2 response to guaranty
the maintain of the fetus. It
can conduct to a vertical transmission
of N. caninum leading
in many cases to abortion. The
fetal immune system is efficient
after 4 months of pregnancy and
can act against the parasite leading
to viable but seropositive
calves.
Vaccination can be modelised in
mouse and lead to the development
of a commercially available
vaccine in bovine allowing
a reduction of clinical signs and
abortions in host but not systematically.
The understandding
of the host-parasite interaction
should allow to more accurately
act in a prophylactic way to this
pathogen. Get the PDF Contact person : fghalmi@yahoo.fr |