Neospora caninum infection during early pregnancy in cattle: Influence of the isolate on abortion timing and immune responses

The pathogenesis of abortion caused by Neospora caninum is complex, and different factors determine the outcome of infection, including gestation duration and foetal immunocompetence. Studies focused on the potential influence of the specific N. caninum isolate on abortion are very limited. In this work, we investigated the role of N. caninum intra-species diversity on the abortion outcome in cattle. Cows were intravenously inoculated at day 70 of pregnancy with 107 tachyzoites of two isolates that show marked differences in virulence in vitro and in mouse models: Nc-Spain7 (group 1, n=6), a high virulence isolate, and Nc-Spain8 (group 2, n=6), a low-to-moderate virulence isolate. Control cows (n=5) were inoculated with Marc-145 host cells. After inoculation, pregnancy was monitored, and dams were culled when foetal death was detected. Abortion occurred in all infected cows between days 24 and 49 post-infection; however, abortion occurred sooner in group 1 (median abortion day= 34) than in group 2 (median abortion day= 41). Similar histological lesions were found in all placentas (cotyledons and caruncles) and in most of the foetuses from the two infected groups. However, parasites were more frequently detected in the placenta and foetal tissues by PCR and in the brain by immunohistochemistry in group 1. Specific antibodies were detected from day 15 p.i. in all infected cattle, with a trend towards higher IgG levels in group 1. Differences in the IFN-γ and IL-4 secretion profiles were also found between infected groups in the lymphostimulation assays. Both infected groups showed significant increases in the levels of cytokine mRNAs (IFN-γ, IL-4, IL-10, IL-12p40 and TNF-α) produced in the placenta, and higher levels were found in the caruncles than in the cotyledons. Differences were also found between the infected groups: the IFN-γ levels were significantly increased in the caruncles of group 1, whereas higher IL-10 levels were detected for group 2.

Bibliographic Details

Main Authors:	Regidor-Cerrillo, Javier, Arranz-Solís, D., Benavides, Julio, Castro-Hermida, J. A., Mezo, Mercedes, Gómez-Bautista, Mercedes, Pérez Pérez, Valentín, Ortega Mora, Luis M., González-Warleta, M.
Format:	póster de congreso biblioteca
Language:	English
Published:	Sociedade Portuguesa de Ciências Veterinárias 2012-10
Online Access:	http://hdl.handle.net/10261/76232
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