SALUVET, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Madrid, Spain.
PLoS One. 2013 Aug 6;8(8):e72678. doi: 10.1371/journal.pone.0072678. Print 2013.
The cyst-forming protozoan parasite Neosporacaninum is one of the main causes of bovine abortion worldwide and is of great economic importance in the cattle industry. Recent studies have revealed extensive genetic variation among N. caninum isolates based on microsatellite sequences (MSs). MSs may be suitable molecular markers for inferring the diversity of parasite populations, molecular epidemiology and the basis for phenotypic variations in N. caninum, which have been poorly defined. In this study, we evaluated nine MS markers using a panel of 11 N. caninum-derived reference isolates from around the world and 96 N. caninum bovine clinical samples and one ovine clinical sample collected from four countries on two continents, including Spain, Argentina, Germany and Scotland, over a 10-year period. These markers were used as molecular tools to investigate the genetic diversity, geographic distribution and population structure of N. caninum. Multilocus microsatellite genotyping based on 7 loci demonstrated high levels of genetic diversity in the samples from all of the different countries, with 96 microsatellite multilocus genotypes (MLGs) identified from 108 N. caninum samples. Geographic sub-structuring was present in the country populations according to pairwise F(ST). Principal component analysis (PCA) and Neighbor Joining tree topologies also suggested MLG segregation partially associated with geographical origin. An analysis of the MLG relationships, using eBURST, confirmed that the close genetic relationship observed between the Spanish and Argentinean populations may be the result of parasite migration (i.e., the introduction of novel MLGs from Spain to South America) due to cattle movement. The eBURST relationships also revealed genetically different clusters associated with the abortion. The presence of linkage disequilibrium, the co-existence of specific MLGs to individual farms and eBURST MLG relationships suggest a predominant clonal propagation for Spanish N. caninum MLGs in cattle.
囊形成原虫寄生虫 Neosporacaninum 是世界范围内导致牛流产的主要原因之一，在养牛业中具有重要的经济意义。最近的研究表明，基于微卫星序列 (MSs)，N. caninum 分离株之间存在广泛的遗传变异。MSs 可能是推断寄生虫种群多样性、分子流行病学和 N. caninum 表型变异基础的合适分子标记，而这些方面的研究还很不完善。在本研究中，我们使用来自世界各地的 11 个 N. caninum 参考分离株和 96 个 N. caninum 牛临床样本以及来自两个大陆的四个国家（西班牙、阿根廷、德国和苏格兰）的一个绵羊临床样本的小组评估了 9 个 MS 标记物。这些标记物被用作分子工具，以研究 N. caninum 的遗传多样性、地理分布和种群结构。基于 7 个位点的多位点微卫星基因分型显示，来自所有不同国家的样本具有高水平的遗传多样性，从 108 个 N. caninum 样本中鉴定出 96 个微卫星多位点基因型 (MLG)。根据成对 F(ST)，国家群体中存在地理亚结构。主成分分析 (PCA) 和邻接聚类树拓扑也表明，MLG 分离部分与地理起源相关。使用 eBURST 对 MLG 关系的分析证实，西班牙和阿根廷种群之间观察到的密切遗传关系可能是由于牛的迁移导致寄生虫的迁移（即从西班牙向南美洲引入新的 MLG）。eBURST 关系还揭示了与流产相关的遗传不同聚类。连锁不平衡的存在、特定 MLG 与单个农场共存以及 eBURST MLG 关系表明，西班牙 N. caninum MLG 在牛中存在主要的无性繁殖。
