Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu, Sichuan, China.
Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu, Sichuan, China.
Acta Trop. 2021 Sep;221:105989. doi: 10.1016/j.actatropica.2021.105989. Epub 2021 May 28.
The prevalence of E. multilocularis is a major public health problem in China. To better understand the molecular epidemiology and evolutionary patterns of E. multilocularis, an adequate dataset regarding the genetic variance of this parasite is necessary. However, for now, available genetic data of E. multilocularis is still insufficient. In the study, the EmsB microsatellite and the partial mitochondrial cox1 gene were combined to investigate the genetic diversity of 64 E. multilocularis samples from human, dogs and voles. These samples were collected in the Western Sichuan Plateau, where the highest village-based human prevalence of alveolar echinococcosis was recorded worldwide. The aim of the study is to gather more informative genetic data of E. multilocularis in the areas, especially those obtained using the EmsB marker. The microsatellite analysis revealed 7 different EmsB profiles, 1 of which was found in 90.63% of the total samples collected from all 3 hosts. This major profile was identical to the one detected in the same area 16 years ago. The rest of the 6 profiles, each represented by only 1 isolate, did not correspond to any of the profiles previously reported. All the profiles detected in the study belonged to the Asian cluster. Meanwhile, according to sequence analysis of the 758 bp cox1 region, 4 haplotypes all assigned to the Asian clade were detected among the isolates. A star-like haplotype network was exhibited with a centrally positioned haplotype found in 93.75% of the samples. The overall haplotype and nucleotide diversities were both low. These findings provided evidence for a founder event or bottleneck and subsequent population expansion in E. multilocularis. The EmsB profiles were not fully consistent with the cox1 haplotypes. The same correspondence relationship was mainly observed in samples with the major profile P5 and the main haplotype EmHa1. A total of 54 isolates assigned to profile P5 were classified to the EmHa1 haplotype. In conclusion, both the microsatellite and mtDNA markers showed low variability within the Tibetan population of E. multilocularis. An EmsB profile and a cox1 haplotype were found to be predominant in the study area, which appears to remain steady for over a decade. The results reinforce the higher potential of the microsatellite DNA marker with high discriminative power to identify the very low genetic polymorphism of E. multilocularis than that of the partial cox1 sequencing. The data obtained in the study would be helpful to enlarge the data pool to further probe the possible origins and dispersal of E. multilocularis in China.
泡状棘球蚴病在中国是一个主要的公共卫生问题。为了更好地了解泡状棘球蚴的分子流行病学和进化模式，有必要获得关于该寄生虫遗传变异的充分数据集。然而，目前，泡状棘球蚴的可用遗传数据仍然不足。在这项研究中，我们将 EmSB 微卫星和部分线粒体 cox1 基因结合起来，调查了来自人类、狗和田鼠的 64 个泡状棘球蚴样本的遗传多样性。这些样本是在世界范围内记录到最高村落型泡状棘球蚴感染率的川西高原地区收集的。本研究的目的是在该地区收集更多关于泡状棘球蚴的信息性遗传数据，特别是使用 EmSB 标记获得的数据。微卫星分析显示了 7 种不同的 EmSB 图谱，其中 1 种在从所有 3 种宿主中收集的总样本中发现占 90.63%。这一主要图谱与 16 年前在同一地区检测到的图谱相同。其余 6 种图谱，每种图谱仅代表 1 个分离株，与以前报道的任何图谱都不对应。本研究中检测到的所有图谱都属于亚洲聚类。同时，根据 cox1 区 758bp 序列分析，在分离株中检测到 4 种属于亚洲支系的单倍型。在星状单倍型网络中，中心位置的单倍型在 93.75%的样本中发现。总体单倍型和核苷酸多样性都很低。这些发现为泡状棘球蚴的创始事件或瓶颈以及随后的种群扩张提供了证据。EmSB 图谱与 cox1 单倍型不完全一致。在主要图谱 P5 和主要单倍型 EmHa1 中主要观察到相同的对应关系。总共 54 个被归类为 P5 图谱的分离株被归类为 EmHa1 单倍型。总之，在青藏高原地区的泡状棘球蚴群体中，微卫星和 mtDNA 标记都显示出较低的变异性。在研究区域发现了一种 EmSB 图谱和一种 cox1 单倍型占主导地位，这似乎在十多年来一直保持稳定。结果表明，微卫星 DNA 标记比部分 cox1 测序具有更高的分辨力，能更有效地识别泡状棘球蚴的遗传多态性较低的特征。本研究获得的数据有助于扩大数据池，进一步探讨泡状棘球蚴在中国的可能起源和传播。
