The present study examined the molecular organisation and sequence variation in the nuclear ribosomal DNA (rDNA) region, including the two internal transcribed spacers (ITS1 and ITS2) and the 5.8S gene of the Clonorchis sinensis from the Russian Far East. The relevant sequences from other parts of this species' area were downloaded from GenBank. The results showed 100% identity for all investigated 5.8S-ITS2 rDNA sequences. In contrast, two levels of intraspecific variations were revealed in the complete ITS1 sequences. The intra-genomic variation resulted from a C/T polymorphism in a single position. The inter-individual differences between the ITS1 sequences were both due to nucleotide and size polymorphisms resulting from a varying number of five-nucleotide repeats and followed by two ITS1 length variants. These variant frequencies correlate with the clonorchiasis level in some geographical localities. ITS1 differences, both in the mutation profile and mutation localisation, were revealed between northern and southern geographical samples. The presence of GC boxes that are identical to known regulatory motifs in eukaryotes was detected within the ITS1 sub-repeats. The predicted secondary structures for ITS1 consist of two large branches, one of which was invariable, while another depended on ITS1 length. The predicted secondary structure for ITS2 includes four helices around the core. The main differences between C. sinensis and other opisthorchids were localised on the tops of helices 2, 3, and 4. A phylogenetic MST reconstruction subdivided all ITS1 sequences into two well differentiated clusters, each with the major widespread ribotype, and showed that ribotype diversity in both Russia and Korea is much lower than in China. The results obtained demonstrate the feasibility of complete ITS1 sequences in C. sinensis population genetics and can be considered as a basis for further studies of the parasite infection because they may help to elucidate the molecular mechanisms of pathogen evolution and adaptation.
"i et al . , 2006 ) . There are a number of examples that certain molecu - lar characteristics of parasites are closely correlated with their adaptive ability and infectivity ( e . g . Schönian et al . , 2001 ; Rooney , 2004 ; Subbotin et al . , 2011 ) . We came to the same conclu - sion based on data of the nuclear rDNA sequences of C . sinensis ( Tatonova et al . , 2012 ) . Additionally , there is evidence that genes associated with infection or resistance to infection have particu - larly high rates of molecular evolution ( Blanc et al . , 2005 ; Obbard et al . , 2006 ; Barrett et al . , 2009 ) . At the very least , it may be impor - tant for C . sinensis populations that the ability of parasites to e"
[Show abstract][Hide abstract] ABSTRACT: Clonorchiasis is a parasitic disease of high public health importance in many countries in southeastern Asia and is caused by the Chinese liver fluke Clonorchis sinensis. However, the genetic structure and demographic history of its populations has not been sufficiently studied throughout the geographic range of the species and available data are based mainly on partial gene sequencing. In this study, we explored the genetic diversity of the complete 1560 bp cytochrome c oxidase subunit 1 (cox1) gene sequence for geographically isolated C. sinensis populations in Russia and Vietnam, to our knowledge for the first time. The results demonstrated low nucleotide and high haplotype differentiation within and between the two compared regions and a clear geographical vector for the distribution of genetic diversity patterns among the studied populations. These results suggest a deep local adaptation of the parasite to its environment including intermediate hosts and the existence of gene flow across the species' range. Additionally, we have predicted an amino acid substitution in the functional site of the COX1 protein among the Vietnamese populations, which were reported to be difficult to treat with praziquantel. The haplotype networks consisted of several region-specific phylogenetic lineages, the formation of which could have occurred during the most extensive penultimate glaciations in the Pleistocene Epoch. The patterns of genetic diversity and demographics are consistent with population growth of the liver fluke in the late Pleistocene following the Last Glacial Maximum, indicating the lack of a population bottleneck during the recent past in the species' history. The data obtained have important implications for understanding the phylogeography of C. sinensis, its host-parasite interactions, the ability of this parasite to evolve drug resistance, and the epidemiology of clonorchiasis under global climate change.
International Journal for Parasitology 08/2014; 44(11). DOI:10.1016/j.ijpara.2014.06.009 · 3.87 Impact Factor
"Despres et al. found no differences among the ITS2 sequences of S. mansoni from several geographical locations in Africa and the western hemisphere . Similar results were reported for E. revolutum, Clonorchis sinensis, and Opisthorchis viverrini [26–28]. Thus, the ITS2 sequence is a useful marker for identifying closely related trematode species. "
[Show abstract][Hide abstract] ABSTRACT: Sequences of the complete nuclear ribosomal DNA (rDNA) gene from five individual Paramphistomum cervi were determined for the first time. The five complete rDNA sequences, which included the 18S rDNA, the internal transcribed spacer 1 (ITS1), the 5.8S rDNA, the internal transcribed spacer 2 (ITS2), the 28S rDNA, and the intergenic spacer (IGS) regions, had a length range of 8,493-10,221 bp. The lengths of the investigated 18S, ITS1, 5.8S, ITS2, and 28S rDNA sequences, which were 1,994 bp, 1,293 bp, 157 bp, 286 bp, and 4,186 bp, respectively, did not vary. However, the IGS rDNA sequences had a length range of 577-2,305 bp. The 5.8S and ITS-2 rDNA sequences had 100% identity among the five investigated samples, while the identities among the IGS had a range of 53.7-99.8%. A comparative analysis revealed that different types and numbers of repeats were found within each ITS1 and IGS region, which may be related to the length polymorphism of IGS. The phylogenetic position of P. cervi in Paramphistomatidae was analyzed based on the 18S rDNA sequences. These results will aid in studying the intra- and interspecific variation of the Paramphistomatidae and the systematics and phylogenetics of Digenea.
[Show abstract][Hide abstract] ABSTRACT: Background:
Clonorchiasis is of considerable public health importance, particularly in the People's Republic of China (PR China), where most of the 15 million individuals infected with Clonorchis sinensis are currently concentrated. Praziquantel is the drug of choice, but tribendimidine might be an alternative.
We performed a randomized open-label trial in Guangxi, PR China, to assess the efficacy and safety of 400 mg tribendimidine once, 400 mg tribendimidine daily for 3 days, and 75 mg/kg praziquantel in 1 day divided in 3 doses against parasitological-confirmed C. sinensis infections. Cure and egg reduction rates were determined 3 weeks posttreatment using available case analysis. Clinical symptoms were documented at baseline, and adverse events were recorded and graded 3 and 24 hours after each dose.
A total of 74 patients were included in the final analysis. Single-dose tribendimidine achieved a cure rate of 44%, whereas cure rates of 58% and 56% were obtained for tribendimidine administered for 3 days and praziquantel, respectively. High egg reduction rates (97.6%-98.8%) were observed for all treatment regimens. Single-dose tribendimidine was the best-tolerated treatment scheme. Patients treated with praziquantel experienced significantly more adverse events than did tribendimidine recipients (P < .05).
Tribendimidine has an efficacy comparable to praziquantel in the treatment of C. sinensis infection and resulted in fewer adverse events compared to praziquantel. Larger clinical trials are warranted among C. sinensis-infected patients to determine the potential of tribendimidine against clonorchiasis and other helminthiases. Clinical Trials Registration.Controlled-Trials.com, ISRCTN80829842.
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