Hecker Anna Sophie, Raulf Marie-Kristin, König Sven, May Katharina, Strube Christina
Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Germany.
Institute of Animal Breeding and Genetics, Justus-Liebig-University Gießen, Gießen, Germany.
Parasit Vectors. 2025 Feb 13;18(1):51. doi: 10.1186/s13071-025-06701-6.
The liver fluke Fasciola hepatica is one of the most important endoparasites in domestic ruminants worldwide and can cause considerable economic losses. This study presents the first population genetic analysis of F. hepatica in Germany and aims at providing new insights into genetic diversity and population structure.
A total of 774 liver flukes, collected from 60 cows of 17 herds and 13 cows of unknown herd origin, were subjected to comparative analysis of two mitochondrial genes (cox1 and nad1), one nuclear region (internal transcribed spacer (ITS)-1) and eight nuclear microsatellite markers. In addition, individual fluke measurements allowed comparison of morphometric differences between genotypes.
The nuclear ITS-1 region showed minimal variability, with 772 of 774 flukes having identical sequences, while the mitochondrial sequences revealed a high genetic diversity, with 119 distinct haplotypes, a mean haplotype diversity (Hd) of 0.81 and a mean nucleotide diversity (π) of 0.0041. Mitochondrial phylogenetic analysis identified two clusters with no clear association with the host or farm of origin. In the microsatellite analysis, all eight loci were highly polymorphic, with a mean allele frequency of 19.0 and a mean genotype frequency of 73.5 per locus. A total of 500 unique multilocus genotypes (MLGs) were found across all fluke samples, indicating that 68.5% of all genotypes were unique. A mean expected heterozygosity of 0.71 suggested a high potential for adaptability and the number of migrants (Nm = 3.5) indicated high gene flow between farms. Population structure analysis based on microsatellite data revealed that flukes from two farms differed genetically from the others. Linear mixed model results revealed that fluke length differed significantly between the two mitochondrial clusters, although it should be noted that fluke age could not be considered in the analyses.
Fasciola hepatica in German dairy farms showed high genetic diversity and gene flow. The differences in population structure identified by mitochondrial sequences compared with microsatellite loci highlight the benefits of analysing genetic markers of different origins. This is the first study to correlate fluke morphometry measurements with genetic markers, indicating that the identified markers can influence fluke size.
肝片吸虫是全球家养反刍动物中最重要的体内寄生虫之一，可造成相当大的经济损失。本研究首次对德国的肝片吸虫进行了群体遗传学分析，旨在为遗传多样性和群体结构提供新的见解。
从17个牛群的60头牛和来源不明牛群的13头牛中收集了总共774条肝片吸虫，对两个线粒体基因（cox1和nad1）、一个核区域（内转录间隔区（ITS）-1）和八个核微卫星标记进行了比较分析。此外，对单个吸虫的测量允许比较不同基因型之间的形态差异。
核ITS-1区域显示出最小的变异性，774条吸虫中有772条具有相同的序列，而线粒体序列显示出高度的遗传多样性，有119个不同的单倍型，平均单倍型多样性（Hd）为0.81，平均核苷酸多样性（π）为0.0041。线粒体系统发育分析确定了两个聚类，与宿主或起源农场没有明显关联。在微卫星分析中，所有八个位点都具有高度多态性，每个位点的平均等位基因频率为19.0，平均基因型频率为73.5。在所有吸虫样本中总共发现了500个独特的多位点基因型（MLG），表明所有基因型中有68.5%是独特的。平均预期杂合度为0.71，表明具有很高的适应潜力，迁移个体数量（Nm = 3.5）表明农场之间有很高的基因流动。基于微卫星数据的群体结构分析表明，来自两个农场的吸虫在基因上与其他吸虫不同。线性混合模型结果显示，两个线粒体聚类之间的吸虫长度存在显著差异，不过应该注意的是，分析中没有考虑吸虫的年龄。
德国奶牛场的肝片吸虫表现出高度的遗传多样性和基因流动。与微卫星位点相比，线粒体序列确定的群体结构差异突出了分析不同来源遗传标记的好处。这是第一项将吸虫形态测量与遗传标记相关联的研究，表明所确定的标记可以影响吸虫大小。
