Abstract
BackgroundDespite the public health importance of toxocariasis/toxascariasis, only a few species of these ascaridoid parasites from wild canine and feline carnivores have been studied at the molecular level so far. Poor understanding of diversity, host distribution and the potential (zoonotic) transmission of the ascaridoid species among wild animals negatively affects their surveillance and control in natural settings. In this study, we updated previous knowledge by profiling the genetic diversity and phylogenetic relationships of ascaridoid species among eleven wild canine and feline animals on the basis of a combined analysis of the ribosomal internal transcribed spacer region (ITS) gene and the partial mitochondrial cytochrome c oxidase subunit 2 (cox2) and NADH dehydrogenase subunit 1 (nad1) genes.ResultsIn total, three genetically distinct ascaridoid lineages were determined to be present among these wild carnivores sampled, including Toxocara canis in Alopex lagopus and Vulpes vulpes, Toxocara cati in Felis chaus, Prionailurus bengalensis and Catopuma temmincki and Toxascaris leonina in Canis lupus, Panthera tigris altaica, Panthera tigris amoyensis, Panthera tigris tigris, Panthera leo and Lynx lynx. Furthermore, it was evident that T. leonina lineage split into three well-supported subclades depending on their host species, i.e. wild felids, dogs and wolves and foxes, based on integrated genetic and phylogenetic evidence, supporting that a complex of T. leonina other than one species infecting these hosts.ConclusionsThese results provide new molecular insights into classification, phylogenetic relationships and epidemiological importance of ascaridoids from wild canids and felids and also highlight the complex of the taxonomy and genetics of Toxascaris in their wild and domestic carnivorous hosts.
Highlights
Ascaridoid nematodes of the genera Toxocara (Toxocaridae) and Toxascaris (Ascarididae) are the most common intestinal parasites among carnivores of the families Canidae and Felidae [1, 2]
The conserved and genus-specific nucleotide sites of internal transcribed spacer region (ITS), cox2 and nad1were identified by adding the congeneric species T. canis, T. cati, T. malaysiensis and T. vitulorum as well as T. leonina and other related species, Baylisascaris spp. and Ascaris spp
We mainly focused on the conserved sites in these two mitochondrial genes and detected their variable sites in the same regions as well, in order to determine if the base conservations were Toxocara and Toxascaris-specific and if there were nonsynonymous substitutions apparent in these two genes by respective comparisons of their protein sequences in representative specimens
Summary
Ascaridoid nematodes of the genera Toxocara (Toxocaridae) and Toxascaris (Ascarididae) are the most common intestinal parasites among carnivores of the families Canidae and Felidae [1, 2]. Considering that single rDNA or mtDNA loci only allow limited inference of molecular analyses [24] and that current sampling and studies mostly focus on domestic animal-originated Toxocara and Toxascaris [4, 12], it would be essential and urgent to develop a combined analysis of nuclear and mitochondrial data for more accurate and robust branches in ascaridoids from a wider host-range that includes wild canids and felids. We updated previous knowledge by profiling the genetic diversity and phylogenetic relationships of ascaridoid species among eleven wild canine and feline animals on the basis of a combined analysis of the ribosomal internal transcribed spacer region (ITS) gene and the partial mitochondrial cytochrome c oxidase subunit 2 (cox2) and NADH dehydrogenase subunit 1 (nad1) genes
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