Abstract Background Horses can suffer from gastrointestinal (GI) disease in domestic environments, often precipitated by human‐led changes in management. Understanding the consequences of these changes on equine gut microbiota is key to the prevention of such disease episodes. Objective Profile the faecal microbiota of adult female Exmoor ponies under three management conditions, representing increasing levels of management by humans, encompassing different diets; whilst controlling for age, breed and sex. Study design Cross‐sectional descriptive. Methods Faecal samples were collected from three populations of Exmoor ponies kept under contrasting management conditions: 29 adult female ponies in groups with low management (LM) ( n = 10), medium management (MM) ( n = 10) and high management (HM) ( n = 9) levels, based on diet, drug use, handling and exercise. Faecal microbial composition was profiled via high‐throughput sequencing of the bacterial 16S rRNA gene, and functional metagenome predictions. Results We observed profound step‐wise changes in microbiome structure in the transition from LM to MM to HM. A relatively high abundance of Proteobacteria and Tenericutes was associated with the HM group; higher abundance of Methanobacteria was observed in the LM group. The MM group had intermediate levels of these taxa and exhibited high ‘within group’ variation in alpha diversity. Functional predictions revealed increased amino acid and lipid metabolism in HM; energy metabolism in LM and carbohydrate metabolism and immune/metabolic disease pathways in MM. Main limitations Low group sizes, incomplete knowledge of bacterial genomes in equine gut microbiota and it was not possible to assess the relative impact of diet, drug use, handling and exercise on the microbiome as variables were confounded. Conclusions Human‐led management factors had profound step‐wise effects on faecal microbial composition. Based on functional metagenome predictions, we hypothesise that dietary differences between groups were the major driver of observed differences.
Anthelmintic resistance is a global problem that threatens sustainable control of the equine gastrointestinal cyathostomins (Phylum Nematoda; Superfamily Strongyloidea). Of the three novel anthelmintic classes that have reached the veterinary market in the last decade, none are currently licenced in horses, hence current control regimens focus on prolonging the useful lifespan of licenced anthelmintics. This approach would be facilitated by knowledge of the resistance mechanisms to the most widely used anthelmintics, the macrocyclic lactones (ML). There are no data regarding resistance mechanisms to MLs in cyathostomins, although in other parasitic nematodes, the ABC transporters, P-glycoproteins (P-gps), have been implicated in playing an important role. Here, we tested the hypothesis that P-gps are, at least in part, responsible for reduced sensitivity to the ML ivermectin (IVM) in cyathostomins; first, by measuring transcript levels of pgp-9 in IVM resistant versus IVM sensitive third stage larvae (L3) pre-and post-IVM exposure in vitro. We then tested the effect of a range of P-gp inhibitors on the effect of IVM against the same populations of L3 using the in vitro larval development test (LDT) and larval migration inhibition test (LMIT). We demonstrated that, not only was pgp-9 transcription significantly increased in IVM resistant compared to IVM sensitive L3 after anthelmintic exposure (p < 0.001), but inhibition of P-gp activity significantly increased sensitivity of the larvae to IVM in vitro, an effect only observed in the IVM resistant larvae in the LMIT. These data strongly implicate a role for P-gps in IVM resistance in cyathostomins. Importantly, this raises the possibility that P-gp inhibitor-IVM combination treatments might be used in vivo to increase the effectiveness of IVM against cyathostomins in Equidae.
In spite of the emergence of populations of drug-resistant cyathostomines worldwide, little is known of parasite species responsible for ‘early egg shedding’ in cohorts of horses subjected to treatment with widely used anthelmintics, e.g. ivermectin (IVM). In this study, we determined the cyathostomine egg reappearance period (ERP) after IVM treatment in a cohort of yearlings from a large Thoroughbred (TB) stud farm in the United Kingdom, and identified species of cyathostomines with reduced ERP using a combination of fundamental parasitology techniques coupled with advanced molecular tools. Individual faecal samples were collected from TB yearlings with cyathostomine infection prior to IVM treatment, as well as at 14, 21, 28, 35, 42 and 49 days post-treatment. Faecal egg counts (FEC) were performed for each individual sample for determination of ERPs. In addition, individual larval cultures were performed and representative numbers of third-stage larvae (L3s) harvested from each culture were subjected to molecular species identification via PCR-Reverse Line Blot (RLB). Prior to IVM treatment, 11 cyathostomine species were detected in faecal samples from TB horses enrolled in this study, i.e. Cyathostomum catinatum, Cylicostephanus longibursatus, Cylicostephanus goldi, Cylicocyclus nassatus, Cylicostephanus calicatus, Cyathostomum pateratum, Cylicocyclus radiatus, Paraposteriostomum mettami, Coronocyclus labratus, Cylicocyclus insigne and Cylicocyclus radiatus variant A. Of these, eggs of Cya. catinatum, Cys. longibursatus, Cyc. nassatus and Cyc. radiatus could be detected at 28 days post-treatment, while from day 42 onwards, cyathostomine species composition reflected data obtained pre-IVM treatment, with the exception of eggs of Cor. labratus and Cyc. insigne which could no longer be detected post-IVM administration. This study provides valuable data on the occurrence of IVM-resistance in cyathostomines in the UK. Nevertheless, further investigations are needed to shed light on the prevalence and incidence of drug-resistance in this country, as well as other areas of the world where equine trade is substantial.
The multifaceted interactions occurring between gastrointestinal (GI) parasitic helminths and the host gut microbiota are emerging as a key area of study within the broader research domain of host-pathogen relationships. Over the past few years, a wealth of investigations has demonstrated that GI helminths interact with the host gut flora, and that such interactions result in modifications of the host immune and metabolic statuses. Nevertheless, whilst selected changes in gut microbial composition are consistently observed in response to GI helminth infections across several host-parasite systems, research in this area to date is largely characterised by inconsistent findings. These discrepancies are particularly evident when data from studies of GI helminth-microbiota interactions conducted in humans from parasite-endemic regions are compared. In this review, we provide an overview of the main sources of variance that affect investigations on helminth-gut microbiota interactions in humans, and propose a series of methodological approaches that, whilst accounting for the inevitable constraints of fieldwork, are aimed at minimising confounding factors and draw biologically meaningful interpretations from highly variable datasets.
This report provides an in-depth review of the science and opportunities in microbiome biobanking, inspired by the success of the UK Biobank. It delivers actionable recommendations to establish a world-leading "UK Microbiome Biobank" (UKMB) to support academic and industrial research. The report highlights the importance of microbes in health, agriculture, and the environment, and the need to conserve microbial resources for research and innovation. Key recommendations include establishing the UKMB as a hub-and-spoke model with thematic areas, incorporating existing infrastructure, promoting data and technology exchange, developing standards, and ensuring ethical and regulatory compliance. The UKMB aims to enhance economic competitiveness, support the bioeconomy, and address global challenges.
Reasons for performing study Anthelmintic resistance is a global problem and constitutes a major threat to the welfare of equids worldwide. The cyathostomins are the most numerous and pathogenic gastrointestinal nematode ( GIN ) of equids in the developed world. Cyathostomins show widespread resistance to 2 out of 3 of the major classes of anthelmintic and recently there are reports of reduced efficacy to the potent macrocyclic lactones ( MLs ). None of the 3 novel classes of anthelmintic that have emerged in the last decade are licensed for use in equids. The cysteine proteases ( CPs ) are plant proteins that have shown potent activity against GINs in vivo in sheep and pigs. Objectives This study aimed to evaluate the anthelmintic effect of the CP papain on cyathostomins in vitro using the egg hatch assay ( EHA ) and larval migration inhibition test ( LMIT ). Methods Samples of cyathostomin eggs and third stage larvae were collected and cultured from a population of equids that have recently shown reduced ML efficacy in vivo . The EHA and LMIT were performed on repeated samples with increasing concentrations of papain. Dose–response curves were plotted and PROBIT analysis performed on the data to give EC ‐50 values (concentration that gives 50% of the maximal response). Results Papain caused a dose dependent inhibition of both egg hatch and larval migration. The EC ‐50 values were 2 μmol/l and 100 μmol/l in the EHA and LMIT respectively, indicating a more potent effect on egg hatch. Conclusions The CP papain shows potent anthelmintic activity against cyathostomins in vitro . Good evidence of anthelmintic effect against GINs in other host species is supportive of its potential use in equids. Further work is indicated to evaluate safety and in vivo efficacy. Ethical animal research: The study was approved by the University of L iverpool and Donkey Sanctuary Ethics Committee. Explicit owner informed consent for participation in this study was not stated. Sources of funding: The Donkey Sanctuary, University of L iverpool – Institute of Infection and Global Health. Competing interests: None.
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