Trabajo presentado al: 4th International Meeting on Apicomplexa in Farm
Animals. (11-14 October 2017 - Madrid, Spain).Toxoplasmosis is one the main infectious causes of reproductive failure in sheep where the time
of gestation when sheep are infected affects the clinical and lesional outcome of the disease. In
order to investigate the variations of local and peripheral immune responses during gestation,
pregnant sheep were infected at early, mid and late gestation and subsequently culled at 2, 3
and 4 weeks post infection. In those sheep inoculated during the second term, serological
antibodies were detected earlier and the increase in serological γ-IFN was higher than in the
other infected animals. Regarding the local immune response at the placenta, infiltration of
inflammatory cells was mainly found in the maternal septa, although it also invaded foetal
mesenchyme adjacent to the lesions. The increase in the number of T lymphocytes was
observed only in ewes infected during the second and last terms of gestation while the increase
of B cells occurred in sheep infected at the first and second terms. The expression of iba-1
antigen by macrophages was more frequent after infection during the first term whereas
macrophages expressing lysozyme, CD163 or calprotectin were more frequent in infections at
mid-gestation. A significant increase in the transcription of γ-IFN, when compared to control
animals, occurred after infections in the first and second term, while TNF-α and IL-10
transcription increased only in the second and last term, respectively. There were no differences
when comparing transcription of cytokines between animals infected at different terms of
gestation. This study shows that the time of gestation when infection occurs has a clear influence
over the pathogenesis of ovine toxoplasmosis as a greater inflammatory response was found
after inoculating sheep at the second term of gestation. This finding may explain the later
invasion of the placenta by the parasite at early and mid gestation described in previous studies.This study was founded by AGL2016-75935-C2-2-R and LE080U16 research grants.Peer Reviewe
