Schwantes J B, Quevedo P, D'Ávila M F, Molento M B, Graichen D A S
Graduate Program in Animal Biodiversity, Federal University of Santa Maria, Av. Roraima, 1000, Santa Maria, Rio Grande do Sul, CEP 97105-900, Brazil.
Evolutionary Genetics Laboratory, Federal University of Santa Maria, Av. Independência, 3751, Palmeira das Missões, Rio Grande do Sul, CEP 98300-000, Brazil.
J Helminthol. 2019 Sep 9;94:e83. doi: 10.1017/S0022149X19000774.
Fasciola hepatica is a trematode parasite that affects mammals, including humans. In Brazil, fascioliasis, a disease caused by the parasite, is of great importance. The disorder affects the welfare of the Brazilian population through impairing the agricultural production of cattle, where the disease causes weight loss as a result of liver damage. This study aimed to evaluate the genetic diversity of F. hepatica throughout Southern Brazil to determine its geographic origin and estimate the colonization route of the parasite. To accomplish these aims, flukes were collected from slaughterhouses in three endemic areas of Rio Grande do Sul and Paraná states. DNA was isolated using the phenol-chloroform protocol from single flukes and two mitochondrial genes, cytochrome oxidase subunit I (COI) and nicotinamide dehydrogenase subunit 1 (Nad1), were amplified and sequenced. Ten haplotypes of COI were found from 75 isolated parasites and the total haplotype and nucleotide diversity observed were 0.475 and 0.002, respectively. Using the Nad1 gene, we found 24 haplotypes from 79 samples, resulting in haplotype and nucleotide diversity values of 0.756 and 0.004, respectively. An analysis of molecular variance showed that 57.4% and 77.5% of variation was within populations (FST), while 9.0 and 36.8% of variation was among groups (FCT) when considering COI and Nad1 genes, respectively. For COI, the fixation index values of 0.425 and 0.368 were obtained for FST and FCT, respectively, while analysis of Nad1 0.225 and 0.089 index values were obtained for FST and FCT, respectively. We have determined that F. hepatica found in the two distinct areas originated from several geographical regions, since we found haplotypes that were shared with at least three different continents. These data are in accordance with the recent colonization of Brazil, and the recent import of cattle from South American, European and, possibly, some African countries. The observed FST and FCT values for COI and Nad1 genes of F. hepatica may be a result of limited movement of animals within states and support the lack of geographical structure of the parasite in Brazil, which are in agreement with the observed cattle production systems in this region.
肝片吸虫是一种影响包括人类在内的哺乳动物的吸虫寄生虫。在巴西，由这种寄生虫引起的肝片吸虫病非常重要。该疾病通过损害牛的农业生产影响巴西人口的福祉，在牛群中，这种疾病会因肝脏损伤导致体重减轻。本研究旨在评估巴西南部肝片吸虫的遗传多样性，以确定其地理起源并估计该寄生虫的定殖路线。为实现这些目标，从南里奥格兰德州和巴拉那州三个流行地区的屠宰场收集吸虫。使用酚 - 氯仿法从单个吸虫中分离DNA，并扩增和测序两个线粒体基因，即细胞色素氧化酶亚基I（COI）和烟酰胺脱氢酶亚基1（Nad1）。从75个分离的寄生虫中发现了10种COI单倍型，观察到的总单倍型多样性和核苷酸多样性分别为0.475和0.002。使用Nad1基因，我们从79个样本中发现了24种单倍型，单倍型多样性和核苷酸多样性值分别为0.756和0.004。分子方差分析表明，考虑COI和Nad1基因时，分别有57.4%和77.5%的变异存在于种群内（FST），而分别有9.0%和36.8%的变异存在于群体间（FCT）。对于COI，FST和FCT的固定指数值分别为0.425和0.368，而Nad1分析中FST和FCT的指数值分别为0.225和0.089。我们已经确定，在两个不同地区发现的肝片吸虫起源于几个地理区域，因为我们发现了与至少三个不同大陆共有的单倍型。这些数据与巴西最近的定殖情况以及最近从南美、欧洲以及可能的一些非洲国家进口牛的情况相符。观察到的肝片吸虫COI和Nad1基因的FST和FCT值可能是动物在州内移动受限的结果，并支持该寄生虫在巴西缺乏地理结构，这与该地区观察到的养牛生产系统一致。
