Low genetic diversity in wide-spread Eurasian liver fluke Opisthorchis felineus suggests special demographic history of this trematode species.

Ilja I Brusentsov,Alexey V Katokhin,Boris V Romashov,Sergei N Borovikov,Andrey V Yevtushenko,Lyudmila A Lider,Marat M Suleymanov,Viatcheslav A Mordvinov,Samat K Shibitov,Olga T Rusinek,Irina V Brusentsova,Grigoriy G Goncharenko,Sergei V Shekhovtsov

doi:10.1371/journal.pone.0062453

Abstract

Opisthorchis felineus or Siberian liver fluke is a trematode parasite (Opisthorchiidae) that infects the hepato-biliary system of humans and other mammals. Despite its public health significance, this wide-spread Eurasian species is one of the most poorly studied human liver flukes and nothing is known about its population genetic structure and demographic history. In this paper, we attempt to fill this gap for the first time and to explore the genetic diversity in O. felineus populations from Eastern Europe (Ukraine, European part of Russia), Northern Asia (Siberia) and Central Asia (Northern Kazakhstan). Analysis of marker DNA fragments from O. felineus mitochondrial cytochrome c oxidase subunit 1 and 3 (cox1, cox3) and nuclear rDNA internal transcribed spacer 1 (ITS1) sequences revealed that genetic diversity is very low across the large geographic range of this species. Microevolutionary processes in populations of trematodes may well be influenced by their peculiar biology. Nevertheless, we suggest that lack of population genetics structure observed in O. felineus can be primarily explained by the Pleistocene glacial events and subsequent sudden population growth from a very limited group of founders. Rapid range expansion of O. felineus through Asian and European territories after severe bottleneck points to a high dispersal potential of this trematode species.

Highlights

O. felineus, O. viverrini and Clonorchis sinensis are three species from the genus Opisthorchis (Opisthorchiidae, Trematoda) that are known to cause serious human diseases affecting bile ducts and the gall bladder
Genetic Diversity All O. felineus populations studied here were combined into three geographically isolated groups: Northern Asian (Siberian, the ObIrtysh and the Yenisei river basins), Central Asian (Kazakh, the Nura-Sarysu basin, part of the endorheic Aral-Caspian basin) and East European. This grouping was based on the data of German and Beer on the existence of three O. felineus subspecies in these territories [7,56]
The levels of nucleotide and haplotype diversity were very low across the whole territory studied (Hd = 0.28, 0.61 and 0.18 (ITS1); p = 0.0013, 0.0019 and 0.0004 (ITS1)

Summary

Introduction

O. felineus, O. viverrini and Clonorchis sinensis are three species from the genus Opisthorchis (Opisthorchiidae, Trematoda) that are known to cause serious human diseases affecting bile ducts and the gall bladder. Opisthorchis infection is recognized as the major risk factor of cholangiocarcinoma [1,2,3,4,5]. An estimated 12.5, 67.3 and 601 million people are currently at risk for infection with O. felineus, O. viverrini and C. sinensis, respectively [6]. All species within the genus Opisthorchis are obligate endoparasites with a complex three-host life cycle The first intermediate hosts of O. felineus are sister-species of freshwater snails Bithynia (B. leachi, B. troscheli, B. inflata) [7]. Mature flukes live in the liver of definitive hosts (fish-eating mammals, including humans). Human infections occur by consuming raw or undercooked fish infested with metacercariae

Methods

Results

Discussion

Conclusion