Molecular approaches to differentiate three species of Nematodirus in sheep and goats from China based on internal transcribed spacer rDNA sequences

An Epidemiological Investigation and Drug-Resistant Strain Isolation of Nematodirus oiratianus in Sheep in Inner Mongolia, China

Nematodirus causes major economic losses in the development of the livestock industry, as they are common gastrointestinal parasites of cattle, sheep, and other ruminants. The present study investigated Nematodirus infections in sheep in the Hulunbuir and Xilingol Grasslands, two well-known natural pastures in Inner Mongolia, China. The results indicated that the average infection rate was more than 50%. Furthermore, a naturally occurring strain of Nematodirus was obtained using numerous isolation methods in the survey region. Conventional morphology and molecular biology were used to identify the strain. The larval migration inhibition test was used to determine the ivermectin level in the isolated strain. The results indicated that the larvae belonged to the species Nematodirus oiratianus. The strain was found to be ivermectin-resistant. Thus, these results recorded the detailed development processes of Nematodirus eggs, providing novel insights regarding the prevention and control of nematodes by using conventional anthelmintic regimens and by offering valuable species resources for studying anthelmintic resistance in nematodes.

Advances in diagnosis of gastrointestinal nematodes in livestock and companion animals

Diagnosis of gastrointestinal nematodes in livestock and companion animals has been neglected for years and there has been an historical underinvestment in the development and improvement of diagnostic tools, undermining the undoubted utility of surveillance and control programmes. However, a new impetus by the scientific community and the quickening pace of technological innovations, are promoting a renaissance of interest in developing diagnostic capacity for nematode infections in veterinary parasitology. A cross-cutting priority for diagnostic tools is the development of pen-side tests and associated decision support tools that rapidly inform on the levels of infection and morbidity. This includes development of scalable, parasite detection using artificial intelligence for automated counting of parasitic elements and research towards establishing biomarkers using innovative molecular and proteomic methods. The aim of this review is to assess the state-of-the-art in the diagnosis of helminth infections in livestock and companion animals and presents the current advances of diagnostic methods for intestinal parasites harnessing (i) automated methods for copromicroscopy based on artificial intelligence, (ii) immunodiagnosis, and (iii) molecular- and proteome-based approaches. Regardless of the method used, multiple factors need to be considered before diagnostics test results can be interpreted in terms of control decisions. Guidelines on how to apply diagnostics and how to interpret test results in different animal species are increasingly requested and some were recently made available in veterinary parasitology for the different domestic species.

Characterization of the complete mitochondrial genomes of Nematodirus oiratianus and Nematodirus spathiger of small ruminants

BACKGROUND

Nematodirus spp. are among the most common nematodes of ruminants worldwide. N. oiratianus and N. spathiger are distributed worldwide as highly prevalent gastrointestinal nematodes, which cause emerging health problems and economic losses. Accurate identification of Nematodirus species is essential to develop effective control strategies for Nematodirus infection in ruminants. Mitochondrial DNA (mtDNA) could provide powerful genetic markers for identifying these closely related species and resolving phylogenetic relationships at different taxonomic levels.

METHODS

In the present study, the complete mitochondrial (mt) genomes of N. oiratianus and N. spathiger from small ruminants in China were obtained using Long-range PCR and sequencing.

RESULTS

The complete mt genomes of N. oiratianus and N. spathiger were 13,765 bp and 13,519 bp in length, respectively. Both mt genomes were circular and consisted of 36 genes, including 12 genes encoding proteins, 2 genes encoding rRNA, and 22 genes encoding tRNA. Phylogenetic analyses based on the concatenated amino acid sequence data of all 12 protein-coding genes by Bayesian inference (BI), Maximum likelihood (ML) and Maximum parsimony (MP) showed that the two Nematodirus species (Molineidae) were closely related to Dictyocaulidae.

CONCLUSIONS

The availability of the complete mtDNA sequences of N. oiratianus and N. spathiger not only provides new mtDNA sources for a better understanding of nematode mt genomics and phylogeny, but also provides novel and useful genetic markers for studying diagnosis, population genetics and molecular epidemiology of Nematodirus spp. in small ruminants.