National Research Council (CONICET), Buenos Aires, Argentina.
National Institute of Agrarian Technology (INTA), Buenos Aires, Argentina.
Parasitol Res. 2019 Oct;118(10):2945-2955. doi: 10.1007/s00436-019-06447-y. Epub 2019 Sep 4.
The aim of the present study was to characterize the specific immune response in prepubertal female calves inoculated with Neospora caninum. Forty-eight N. caninum-seronegative 6-month-old Angus female calves were randomly allocated into two groups: group A calves were inoculated subcutaneously (sc) with 1 × 10 tachyzoites of the low virulence NC-Argentina LP1 isolate in sterile phosphate-buffered saline (PBS); group B calves were mock inoculated sc with sterile PBS. Calves from group A developed a specific immune response characterized by the production of IgG antibodies and the expression of IFN-γ and TNF-α cytokines. Animals did not present any febrile reaction or reactions at the site of inoculation. Although chronic N. caninum infection was developed in 50% of calves of group A after inoculation, according to the presence of antibodies against rNc-SAG4, antigen characteristic of bradyzoites, N. caninum antibodies dropped below the cut-off of ELISA from day 210 post-inoculation onwards. Future trials using the same group of inoculated animals will allow the characterization of the evolution of the immune response during pregnancy and to determine whether the immunization with the local isolate is able to prevent congenital transmission and to protect against heterologous challenges.
本研究旨在描述接种 Neospora caninum 的未成年雌性小牛的特异性免疫反应。将 48 头 6 月龄、血清学阴性的 Angus 雌性小牛随机分为两组：A 组小牛经皮下（sc）接种 1×10 个低毒力 NC-Argentina LP1 分离株的速殖子，接种于无菌磷酸盐缓冲液（PBS）中；B 组小牛 sc 接种无菌 PBS。A 组小牛产生了特异性免疫反应，表现为 IgG 抗体的产生以及 IFN-γ 和 TNF-α 细胞因子的表达。动物没有出现任何发热反应或接种部位反应。尽管接种后 A 组 50%的小牛发生了慢性 N. caninum 感染，但根据 rNc-SAG4 抗体的存在，该抗体是缓殖子的特征抗原，从接种后 210 天起，N. caninum 抗体滴度降至 ELISA 截断值以下。使用相同接种动物组的未来试验将允许描述怀孕期间免疫反应的演变，并确定用本地分离株免疫是否能够预防先天性传播并防止异源挑战。
