Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Cholangiocarcinoma Research Institute, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
Int J Parasitol. 2020 Dec;50(14):1133-1144. doi: 10.1016/j.ijpara.2020.06.011. Epub 2020 Aug 29.
Infection by the small liver fluke, Opisthorchis viverrini, causes serious public health problems, including cholangiocarcinoma, in Thailand and southeastern Asian countries. Previous studies have reported that O. viverrini represents a species complex with varying levels of genetic differentiation in Thailand and Lao PDR. In this study, we re-examined population genetic structure and genetic diversity of O. viverrini using extensive samples of the parasite collected over 15 years from 12 geographical localities in Thailand and eight localities in Lao PDR. Parasite life-cycle stages of 721 individuals of O. viverrini (91 cercariae, 230 metacercariae and 400 adult worms) were genotyped using 12 microsatellite loci. Metacercariae exhibited genetic diversity comparable with that of experimentally raised adults: metacercariae can therefore be used to represent O. viverrini populations without the need for laboratory definitive hosts. Data obtained from larval as well as adult worms identified two distinct genetic clusters of O. viverrini. Sequences of a portion of the mitochondrial cox1 gene strongly supported the existence of these two clusters. One, the widespread cluster, was found at all sampled sites. The second cluster occurred only in Phang Khon District, Sakon Nakhon Province (SPk), within the Songkram River wetland in Thailand. A striking feature of our data relates to the temporal dynamics of the SPk cluster, which was largely replaced by representatives of the widespread cluster over time. If the SPk cluster is excluded, no marked genetic differences were seen among O. viverrini populations from Thailand and Lao PDR. The underlying causes of the observed population structure and population dynamics of O. viverrini are not known.
华支睾吸虫感染会导致严重的公共卫生问题，包括在泰国和东南亚国家的胆管癌。先前的研究报告称，华支睾吸虫在泰国和老挝人民民主共和国代表一个具有不同遗传分化水平的种复合体。在这项研究中，我们使用从泰国 12 个地理地点和老挝人民民主共和国 8 个地点在过去 15 年中收集的广泛寄生虫样本，重新检查了华支睾吸虫的种群遗传结构和遗传多样性。使用 12 个微卫星基因座对华支睾吸虫的 721 个个体的寄生虫生活史阶段（91 尾蚴、230 囊蚴和 400 成虫）进行了基因分型。囊蚴表现出与实验饲养成虫相当的遗传多样性：因此，无需实验室确定宿主即可使用囊蚴来代表华支睾吸虫种群。从幼虫和成虫获得的数据确定了华支睾吸虫的两个不同遗传簇。部分线粒体 cox1 基因序列强烈支持这两个簇的存在。一个是广泛分布的簇，在所有采样地点都有发现。第二个簇仅发生在泰国的蓬坤区（SPk），在 Songkram 湿地内。我们的数据的一个显著特征与 SPk 簇的时间动态有关，随着时间的推移，该簇主要被广泛分布的簇代表所取代。如果排除 SPk 簇，则在泰国和老挝人民民主共和国的华支睾吸虫种群之间没有明显的遗传差异。观察到的华支睾吸虫种群结构和种群动态的潜在原因尚不清楚。
