SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Madrid, Spain.
SALUVET-Innova S.L., Faculty of Veterinary Sciences, Complutense University of Madrid, Madrid, Spain.
Vet Res. 2021 Jun 10;52(1):82. doi: 10.1186/s13567-021-00953-7.
Toxoplasma gondii is an important zoonotic agent with high genetic diversity, complex epidemiology, and variable clinical outcomes in animals and humans. In veterinary medicine, this apicomplexan parasite is considered one of the main infectious agents responsible for reproductive failure in small ruminants worldwide. The aim of this study was to phenotypically characterize 10 Spanish T. gondii isolates recently obtained from sheep in a normalized mouse model and in an ovine trophoblast cell line (AH-1) as infection target cells. The panel of isolates met selection criteria regarding such parameters as genetic diversity [types II (ToxoDB #1 and #3) and III (#2)], geographical location, and sample of origin (aborted foetal brain tissues or adult sheep myocardium). Evaluations of in vivo mortality, morbidity, parasite burden and histopathology were performed. Important variations between isolates were observed, although all isolates were classified as "nonvirulent" (< 30% cumulative mortality). The isolates TgShSp16 (#3) and TgShSp24 (#2) presented higher degrees of virulence. Significant differences were found in terms of in vitro invasion rates and tachyzoite yield at 72 h post-inoculation (hpi) between TgShSp1 and TgShSp24 isolates, which exhibited the lowest and highest rates, respectively. The study of the CS3, ROP18 and ROP5 loci allelic profiles revealed only type III alleles in ToxoDB #2 isolates and type II alleles in the #1 and #3 isolates included. We concluded that there are relevant intra- and inter-genotype virulence differences in Spanish T. gondii isolates, which could not be inferred by genetic characterization using currently described molecular markers.
刚地弓形虫是一种重要的动物源性病原体，具有高度的遗传多样性、复杂的流行病学特征以及在动物和人类中不同的临床结局。在兽医领域，这种顶复门寄生虫被认为是导致全球小反刍动物生殖失败的主要传染性病原体之一。本研究的目的是在标准化的小鼠模型和绵羊胎盘细胞系（AH-1）中对最近从绵羊中分离得到的 10 株西班牙刚地弓形虫分离株进行表型特征分析，将其作为感染靶细胞。这些分离株符合遗传多样性（类型 II（ToxoDB #1 和 #3）和 III（#2））、地理位置和来源样本（流产胎儿脑组织或成年绵羊心肌）等参数的选择标准。进行了体内死亡率、发病率、寄生虫负荷和组织病理学评估。尽管所有分离株均被归类为“非毒力型”（<30%累积死亡率），但仍观察到了分离株之间的重要差异。分离株 TgShSp16（#3）和 TgShSp24（#2）表现出更高的毒力。在感染后 72 小时（hpi）时，分离株 TgShSp1 和 TgShSp24 的体外入侵率和速殖子产量存在显著差异，这两个分离株的入侵率和速殖子产量分别最低和最高。对 CS3、ROP18 和 ROP5 基因座等位基因谱的研究表明，在 ToxoDB #2 分离株中仅存在 III 型等位基因，而在包括 #1 和 #3 分离株中存在 II 型等位基因。我们得出结论，西班牙刚地弓形虫分离株存在显著的基因型内和基因型间毒力差异，这不能通过目前描述的分子标记进行遗传特征推断。
