Toll-like receptors 3, 7 and 8 are upregulated in the placental caruncle and fetal spleen of Neospora caninum experimentally infected cattle

•TLR modulation by Neospora caninum in placental and fetal tissues was evaluated.•Higher basal TLRs levels in fetal spleen compared with placental tissues.•TLRs 3, 7 and 8 were upregulated mostly in caruncle from N. caninum-infected heifers.•TLRs 3 and 8 were upregulated in fetal spleen from N. caninum-infected animals. Innate immune responses at the maternal-fetal interface are key in the pathogenesis of Neospora caninum, an obligate parasite that causes abortion in cattle. Herein, we determined the gene expression of endosomal Toll-like receptors (TLRs) in the placenta and fetuses from both non-infected pregnant heifers and pregnant heifers intravenously challenged with live tachyzoites of N. caninum on day 70 of gestation. On day 104 of pregnancy, mRNA expression of TLRs 3 and 8, as well as that of TLRs 7 and 9, was high in the spleen of fetuses from N. caninum-infected heifers. Gene expression levels of endosomal TLRs were also detectable in the placenta and the maternal caruncle from infected heifers, being TLRs 3, 7 and 8 particularly upregulated, mostly in the caruncle. Basal TLR levels were higher in fetal spleen than in placental tissues. This study provides novel information on how innate TLR responses are induced at the maternal-fetal interface of cattle in response to intracellular N. caninum.