Authors

ME Oakland¹; M Hegarty¹; PM Brophy¹; E Scott-Baird²; RM Morphew¹;  ¹ Aberystwyth University, UK;  ² Drayton Animal Health, UK

Discussion

Gastrointestinal (GI) nematodes are  a worldwide threat to sustainable farming and animal production. Specifically, the GI nematode Nematodirus helvetianus is a parasite of veterinary importance with cattle infected following the ingestion of infective L3 larvae found in pasture. The life cycle of N. helvetianus is direct. The larvae develop into mature adult worms in the small intestine excreting eggs in the faeces into the environment. Calves with naïve immunity are susceptible, and infection results in scouring, dehydration, and malnutrition. Thus, infection negatively impacts animal welfare and economic production. Furthermore, age-related resistance has been observed yet coinfection with other GI nematode populations can have detrimental effects. N. helvetianus is particularly problematic for pasture-based herds, as the larvae moults occur within the ensheathed eggs. This makes them resistant to harsh climates and desiccation, leading to a mass hatch and an accumulation of infectious L3 larvae in the spring. In addition, as the larvae and eggs can survive on the pasture for months to years, this renders control difficult for pasture-based herds. Currently, anthelmintics and alternate grazing strategies are used in control. However, the increasing challenge of resistance due to the misuse of anthelmintics, and the pressure of climate change, there is a need for novel control strategies. Recently, the use of omic technologies, such as genomics, transcriptomics and proteomics, in the control of related GI helminths offers hope for the alternative control of Nematodirus. At present, knowledge and thus omic resources focused on N. helvetianus are extremely limited; emphasised with the lack of an available genome or transcriptome datasets. Therefore, this project aims to generate the first discovery transcriptome to support future functional genomics in this important GI nematode. Samples of L3 larvae N. helvetianus were purified using a Baermann funnel and snap frozen prior to tRNA extraction. tRNA extractions were completed using Trizol and mechanical bead beating followed by purification using the Zymo spin column methodology. Transcriptome sequencing is currently underway.  In addition,  N. helvetianus are currently undergoing protein extraction to perform preliminary proteomic screening. The whole proteome is to be subjected to global proteomic analysis using a GeLC approach to provide the first evidence of the N. helvetianus proteome.  Finally, of particular interest are the glutathione transferases (GSTs). GSTs have key roles involved in immunomodulation, detoxification, and critical house-keeping roles in cell signalling. These integral roles in helminths make them ideal targets in future control strategies.Initial investigations will focus on a transcriptome-based bioinformatics approach to reveal potential GST members produced by N. helvetianus. Finally, GSTs will be purified using glutathione affinity chromatography and subjected to high resolution proteomic analysis. Therefore, this project will provide support in the pursuit of future anthelmintic targets and future vaccine discovery through transcriptome RNA sequencing and targeted protein purification, aiding further research into host-parasite interactions and parasitic genomics. This is vital in taking the next steps in control of N. helvetianus.