Saluvet, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
Saluvet-innova, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040, Madrid, Spain.
Vet Res. 2019 Sep 24;50(1):72. doi: 10.1186/s13567-019-0691-6.
Early Neospora caninum infection dynamics were investigated in pregnant heifers intravenously inoculated with PBS (G-Control) or 10 tachyzoites of high (G-NcSpain7)- or low (G-NcSpain1H)-virulence isolates at 110 days of gestation. Serial culling at 10 and 20 days post-infection (dpi) was performed. Fever was detected at 1 dpi in both infected groups (P < 0.0001), and a second peak was detected at 3 dpi only in G-NcSpain7 (P < 0.0001). At 10 dpi, Nc-Spain7 was detected in placental samples from one animal related to focal necrosis, and Nc-Spain7 transmission was observed, although no foetal lesions were associated with this finding. The presence of Nc-Spain1H in the placenta or foetuses, as well as lesions, were not detected at 10 dpi. At 20 dpi, G-NcSpain7 animals showed almost 100% positive placental tissues and severe focal necrosis as well as 100% transmission. Remarkably, foetal mortality was detected in two G-NcSpain7 heifers. Only one animal from G-NcSpain1H presented positive placental samples. No foetal mortality was detected, and lesions and parasite transmission to the foetus were not observed in this group. Finally, 100% of G-NcSpain7 heifers at 20 dpi presented specific antibodies, while only 60% of G-NcSpain1H animals presented specific antibodies at 20 dpi. In addition, earlier seroconversion in G-Nc-Spain7 was observed. In conclusion, tachyzoites from Nc-Spain7 reached the placenta earlier and multiplied, leading to lesion development, transmission to the foetus and foetal mortality, whereas Nc-Spain1H showed delayed infection of the placenta and no lesional development or transmission during early infection.
早期刚地弓形虫感染动态的研究，在怀孕的小母牛静脉接种磷酸盐缓冲液（G-对照）或 10 速殖子高（G-NcSpain7）-或低（G-NcSpain1H）-毒力分离株于 110 天妊娠。在感染后 10 天和 20 天（dpi）进行连续淘汰。在两个感染组中，在 1 dpi 时均检测到发热（P<0.0001），仅在 G-NcSpain7 中检测到第二次发热高峰（P<0.0001）。在 10 dpi 时，在与局灶性坏死相关的一个动物的胎盘样本中检测到 Nc-Spain7，并且观察到 Nc-Spain7 的传播，尽管与这一发现相关的没有胎仔病变。在 10 dpi 时，在胎盘或胎仔中未检测到 Nc-Spain1H 的存在，也未检测到病变。在 20 dpi 时，G-NcSpain7 动物的胎盘组织几乎 100%阳性，并且显示出严重的局灶性坏死以及 100%的传播。值得注意的是，在两只 G-NcSpain7 小母牛中检测到胎仔死亡。在 G-NcSpain1H 中只有一只动物的胎盘样本为阳性。在该组中未检测到胎仔死亡，也未观察到病变和寄生虫向胎仔的传播。最后，在 20 dpi 时，G-NcSpain7 小母牛的 100%呈现特异性抗体，而在 20 dpi 时，G-NcSpain1H 动物的 60%呈现特异性抗体。此外，在 G-Nc-Spain7 中观察到更早的血清转化。总之，来自 Nc-Spain7 的速殖子更早到达胎盘并增殖，导致病变发展、向胎仔传播和胎仔死亡，而 Nc-Spain1H 显示出对胎盘的感染延迟，并且在早期感染期间没有病变发展或向胎仔的传播。
