Genetic polymorphisms of Echinococcus tapeworms in China as determined by mitochondrial and nuclear DNA sequences

Abstract

The genetic polymorphisms of Echinococcus spp. in the eastern Tibetan Plateau and the Xinjiang Uyghur Autonomous Region were evaluated by DNA sequencing analyses of genes for mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear elongation factor-1 alpha (ef1a). We collected 68 isolates of Echinococcus granulosus sensu stricto (s.s.) from Xinjiang and 113 isolates of E. granulosus s. s., 49 isolates of Echinococcus multilocularis and 34 isolates of Echinococcus shiquicus from the Tibetan Plateau. The results of molecular identification by mitochondrial and nuclear markers were identical, suggesting the infrequency of introgressive hybridization. A considerable intraspecific variation was detected in mitochondrial cox1 sequences. The parsimonious network of cox1 haplotypes showed star-like features in E. granulosus s. s. and E. multilocularis, but a divergent feature in E. shiquicus. The cox1 neutrality indexes computed by Tajima's D and Fu's Fs tests showed high negative values in E. granulosus s. s. and E. multilocularis, indicating significant deviations from neutrality. In contrast, the low positive values of both tests were obtained in E. shiquicus. These results suggest the following hypotheses: (i) recent Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access

A molecular survey of Echinococcus granulosus sensu lato in central-eastern Europe

“…This sequence type is the most commonly recorded G1 variant in southern Palearctic and it was previously recorded in China (Qinghai province) in sheep [33], in Russia (Altai region) in human [34], in Mongolia in human (GenBank Accession No. AB787538, unpublished), in Turkey in sheep, cattle and human [20,35], in Iran in sheep, human, camel and goat [36] and GenBank Accession No.…”

Phylogenetic Pattern, Evolutionary Processes and Species Delimitation in the Genus Echinococcus

“…Subsequently, much more comprehensive analyses of mtDNA variation in E. granulosus from the Middle East, Europe, China, South Asia, Africa, South America and Australia have found relatively low levels of nucleotide diversity, although greater levels of haplotype diversity, again suggesting rapid population expansion from small founder populations Nakao et al, 2010b;Casulli et al, 2012;Yanagida et al, 2012;Sharma et al, 2013). A comparison of haplotype diversities suggests a Middle Eastern origin for this species (or at least for the switch from a wildlife to a domestic host cycle), with subsequent spread to other parts of the world through anthropogenic transport of hosts (Nakao et al, 2013b).…”

“…Nakao et al (2010b) found low levels of mtDNA diversity in E. multilocularis in the Tibetan Plateau and suggested that the species was introduced to this region by a recent range extension of the red fox (Vulpes vulpes), although this hypothesis requires confirmation because there does not seem to be independent evidence of such a range extension (Kutschera et al, 2013). However, relatively high levels of mtDNA diversity have been found for E. shiquicus in the Tibetan Plateau (Nakao et al 2010b) and E. vogeli in Brazil (Santos et al 2012). Both E.…”

“…Echinococcus shiquicus is thought to have differentiated from E. multilocularis in isolation, presumably during a period of range contraction, with the current sympatric occurrence a result of recent introduction of E. mulilocularis into the Tibetan Plateau with red foxes (Nakao et al, 2010b). …”

Molecular Epidemiology of Cystic Echinococcosis: Genotypic Characterization in Humans and Different Livestock

“…This was the first study to describe the existence of EG senso estricto (G3) in South America and to verify that goats act as a reservoir of E. canadensis (G6) in Neuquén (Soriano et al). Nakao et al (2010), of the Department of Parasitology at Asahikawa Medical College in Hokkaido, Japan, investigated the genetic polymorphisms of Echinococcus spp. in the eastern part of the Tibetan plateau and the Region of Xinjiang, applying a DNA sequencing analysis to the mitochondrial COI and nuclear elongation factor-1 alpha.…”