Peripheral and placental immune responses in goats after primoinfection with Neospora caninum at early, mid and late gestation.

Neospora caninum can cause reproductive failure in goats. However, the pathogenesis of neosporosis in this domestic species remains largely unknown. We recently demonstrated that the outcome of experimental infection by N. caninum in pregnant goats is highly dependent on the time of gestation, during which infection occurs. In the present study, we examined the peripheral and placental immune responses in these groups of goats infected with 10 tachyzoites of the Nc-Spain7 isolate at early (G1, at day 40 of gestation, dg), mid (G2, 90 dg) and late (G3, 120 dg) gestation, together with a group of non-infected goats as a control group (G4). Seroconversion was observed as early as day 10 post-infection (pi) in all goats from G1 that aborted earlier (10-11 pi). The remaining infected goats had seroconverted by day 14 pi. Similar IFN-γ kinetic profiles were found in sera from goats in G1 and G2 with a significant increase in the IFN-γ levels on days 7 and 10 pi. This increase was not observed in G3. A similar pattern of placental cytokine expression was found in all infected groups. IFN-γ and IL-4 showed the highest increase, followed by a weaker up-regulation in TNF-α and IL-10. The lowest up-regulation was observed for IL-12 expression. In summary, this study provides information regarding the dynamics of immune responses and their relationship with the outcome of N. caninum infection in goats during gestation.