Genetic diversity of liver flukes (Fasciola hepatica) from Eastern Europe.

The genetic diversity of liver fluke populations in three different countries from Eastern Europe (Greece, Bulgaria, and Poland) was determined and compared with available data from other countries. Specifically, SNPs from regions of two nuclear genes, 28S rDNA, β-tubulin 3 and an informative region of the mitochondrial genome were examined. Two major lineages for the 28S rDNA gene based on the highly polymorphic 105th nucleotide position were found. These lineages were widely and almost equally spread not only through the countries studied but also in other investigated geographical areas. Two basic lineages and additional haplotypes were defined for the mtDNA gene region which consisted of the cytochrome c oxidase subunit III gene, transfer RNA histidine gene and cytochome b gene. The basic lineages were observed within Greek, Bulgarian, and Polish Fasciola hepatica populations but the distribution of additional haplotypes differed between the populations from the three countries. For the β-tubulin 3 gene multiple polymorphic sites were revealed but no explicit clades. The SNPs were spread unequally in all studied geographical regions with an evident distinction between the Greek and Polish specimens. Additional genotypes for the 28S rDNA region as well as haplotypes of the mtDNA region that were typical for the Greek or Polish populations were observed. Significant polymorphisms for β-tubulin 3 gene were displayed with decreasing percentage of presence within populations from Greece to Poland. There was an amino acid substitution in β-tubulin 3 protein found only among Polish specimens. It is hypothesized that genotypic differences between Greek, Bulgarian, and Polish liver fluke populations are due to territorial division and genetic drift in past epochs.