Role of the bovine immune system and genome in resistance to gastrointestinal nematodes

Transcriptional Profiling of Abomasal Mucosa from Young Calves Experimentally Infected with Ostertagia ostertagi

Ostertagia ostertagi, also known as the brown stomach worm, causes significant pathology in the abomasum, resulting in production and nutritional losses in cattle. Alternative control measures, such as vaccination, are urgently needed because of rapidly growing anthelmintic drug resistance. There is a need to understand host responses to the infection, especially immune responses, to advance vaccine discovery and design. Therefore, the present study investigated comprehensive changes in gene transcription in the abomasal mucosa of cattle infected with O. ostertagi at 0, 3-5, 7-9, 10, and 21 days post-infection (dpi) using RNA sequencing (RNA-seq). Compared to uninfected controls, infected animals exhibited significant increases in differentially expressed genes (DEGs) throughout the infection period. Infection induced more upregulated than downregulated genes in the abomasal fundic mucosa (FUN) when compared to the abomasal pyloric mucosa (PYL). The largest transcriptional changes occurred between 7-9 and 10 dpi during the final development of the L4 and their emergence from the gastric glands. Most DEGs are associated with host immunity, cellular reorganization, cell migration, and proliferation. Tuft/epithelial cell response to the infection was atypical, lacking an anticipated increase in key alarmin cytokine genes. Numerous genes associated with T helper (Th) 1, Th2, and Th17 responses and T cell exhaustion were upregulated, suggesting altered immune regulation. The data collectively indicate that O. ostertagi infection elicits massive host responses, particularly immune responses, which are intertwined with the parasite's disruption of abomasal function, which likely impairs the nutrient utilization of the host. The infection is characterized by the absence of a dominant Th response and displaying a mixed activation of Th1, Th2, and Th17 pathways. Elevated expression of T cell exhaustion genes and lack of increase in epithelial alarmin cytokine genes suggest a downregulation of, or a deficiency in initiating, effective host immunity to the infection. Understanding mechanisms of parasite-mediated immune evasion and their nutritional consequences will facilitate the rational design of protective vaccines against infections of complex nematode parasites.

Mucosal Immunity of Major Gastrointestinal Nematode Infections in Small Ruminants Can Be Harnessed to Develop New Prevention Strategies

Gastrointestinal parasitic nematode (GIN) infections are the cause of severe losses to farmers in countries where small ruminants such as sheep and goat are the mainstay of livestock holdings. There is a need to develop effective and easy-to-administer anti-parasite vaccines in areas where anthelmintic resistance is rapidly rising due to the inefficient use of drugs currently available. In this review, we describe the most prevalent and economically significant group of GIN infections that infect small ruminants and the immune responses that occur in the host during infection with an emphasis on mucosal immunity. Furthermore, we outline the different prevention strategies that exist with a focus on whole and purified native parasite antigens as vaccine candidates and their possible oral-nasal administration as a part of an integrated parasite control toolbox in areas where drug resistance is on the rise.

Genome-wide association study in thoroughbred horses naturally infected with cyathostomins

Cyathostomins are considered one of the most important parasites of horses. A group of horses within a herd can be responsible for eliminating the majority of parasite eggs. This phenotype might be explained by genetic factors. This study aimed to identify genomic regions associated with fecal egg count (FEC) and hematological parameters by performing a genomic-wide association study (GWAS) in Thoroughbred horses naturally infected with cyathostomins. Packed cell volume (PCV), differential leukocyte, and FEC were determined from 90 horses. All animals were genotyped using the Illumina Equine 70 K BeadChip panel containing 65,157 SNP markers. The five genomic windows that have explained the highest percentage of the additive genetic variance of a specific trait (top 5) were further explored to identify candidate genes. A total of 33, 21, 30, 21, and 19 genes were identified for FEC, PCV, eosinophils, neutrophils, and lymphocyte count, respectively. The top 5 marker regions explained 2.86, 2.56, 2.73, 2.33, and 2.37% of the additive genetic variation of FEC, PCV, eosinophils, neutrophils, and lymphocytes count, respectively. This is the first study correlating phenotypic horse health traits to GWAS analysis, which may be used for animal breeding activities, reducing losses due to parasite infections.

Efficacy in US cattle of a novel fixed-dose combination injectable (0.2 mg/kg doramectin + 6.0 mg/kg levamisole hydrochloride) against naturally acquired gastrointestinal nematode infections

Reports of macrocyclic lactone (ML) loss of efficacy suggest ML resistance in gastrointestinal nematodes (GINs) is a growing problem in the US cattle industry. Empirical and modeling data support combining an ML and second anthelmintic from a different drug class to help ML resistance development while effectively treating existing resistant parasite populations. Here, we present a novel fixed-dose combination injectable (FDCI) solution for cattle that delivers 0.2 mg of doramectin and 6.0 mg of levamisole hydrochloride (HCl) per kg of body weight. Field studies were conducted at six sites across the Midwest United States to investigate the efficacy of a single administration of the FDCI in treating common cattle GINs. Cattle (n = 425) with GIN infections confirmed by fecal egg count (FEC) on Day -10( ± 2) were randomly allocated to the control (saline) or treatment (FDCI) group. On Day 0, pre-treatment fecal samples were collected, and cattle were administered a single subcutaneous injection of saline (n = 106) or FDCI (n = 319). Post-treatment fecal samples were collected on Day 14. Fecal egg count reduction tests (FECRTs) were conducted using Day 0 and Day 14 FECs. Efficacy was evaluated using Day 14 FECs (FDCI-treated versus saline-treated). Within treatment, samples collected on Days 0 and 14 with ≥ 20 eggs per gram (EPG) were cultured for nematode larvae recovery and identification. Day -10 FECs for enrolled animals were similar between treatment groups. Coprocultures from cattle with FEC ≥ 20 EPG (n = 68 saline; n = 211, FDCI) on Day 0 showed the presence of Cooperia punctata, Ostertagia spp., Haemonchus spp., C. oncophora, Oesophagostomum spp. and Trichostrongylus spp. Day 14 FECs for FDCI-treated cattle were significantly reduced (0-3 EPG) compared to saline-treated cattle (0-1252 EPG) (p ≤ 0.0042). At all study sites, the efficacy of the new FDCI was ≥ 99.4% and the FECR was 0.99 or 1.00. Day 14 coprocultures from control cattle showed infections of common GIN genera, confirming the efficacy of the FDCI against GINs in the field. A single administration of the doramectin + levamisole HCl combination injectable effectively treats common and economically important cattle GINs.

The Economic Impact of Parasitism from Nematodes, Trematodes and Ticks on Beef Cattle Production

Global human population growth requires the consumption of more meat such as beef to meet human needs for protein intake. Cattle parasites are a constant and serious threat to the development of the beef cattle industry. Studies have shown that parasites not only reduce the performance of beef cattle, but also negatively affect the profitability of beef agriculture and have many other impacts, including contributing to the production of greenhouse gases. In addition, some zoonotic parasitic diseases may also threaten human health. Therefore, ongoing cattle parasite research is crucial for continual parasite control and the development of the beef cattle industry. Parasitism challenges profitable beef production by reducing feed efficiency, immune function, reproductive efficiency, liveweight, milk yield, calf yield and carcass weight, and leads to liver condemnations and disease transmission. Globally, beef cattle producers incur billions (US$) in losses due to parasitism annually, with gastrointestinal nematodes (GIN) and cattle ticks causing the greatest economic impact. The enormity of losses justifies parasitic control measures to protect profits and improve animal welfare. Geographical differences in production environment, management practices, climate, cattle age and genotype, parasite epidemiology and susceptibility to chemotherapies necessitate control methods customized for each farm. Appropriate use of anthelmintics, endectocides and acaricides have widely been shown to result in net positive return on investment. Implementing strategic parasite control measures, with thorough knowledge of parasite risk, prevalence, parasiticide resistance profiles and prices can result in positive economic returns for beef cattle farmers in all sectors.

Global genomic methylation related to the degree of parasitism in cattle

The objective of the present study was to characterize a herd of 72 ½ Angus × ½ Nellore heifers, identify the resistant, resilient and susceptible animals to parasites, relate the overall DNA methylation of these animals with the degree of parasitism, evaluated by the egg count per gram of feces (EPG), Haematobia irritans count (horn fly) and Rhipicephalus microplus count (bovine tick). The experiment was carried out in a completely randomized design, containing 72 treatments, with each animal considered a treatment, and 11 repetitions, with each collection within a year considered a repetition. The data obtained from the counts of the evaluated parasites were subjected to statistical analysis using the SISVAR program, to classify heifers according to the degree of parasitism in low (resistant), intermediary (resilient) and high (susceptible) parasite load for infection by nematodes, infestation by ticks and flies. Addition the animals in these three groups, by hierarchical grouping using the GENES program, heifers were classified as to the degree of parasitism by the three parasites along with the DNA methylation content of the animals in each group. A negative relationship was observed between resistance and methylated DNA content in both classifications, with the resistant, resilient, and susceptible animals showing the highest, intermediate, and lowest methylated DNA quantifications, respectively. Thus, the methodologies used herein enabled the classification of 72 heifers according to the degree of collective infection by gastrointestinal nematodes and infestation by ticks and horn flies, thereby establishing a link between the degree of parasitic resistance in cattle and the global methylated DNA quantification.

Influence of silvopastoral systems on gastrointestinal nematode infection and immune response of Nellore heifers under tropical conditions

Among the strategies for integrating crops, livestock, and forestry, silvopastoral systems must be highlighted due to their inherent microclimatic conditions, mainly in tropical countries such as Brazil, where cattle are frequently subjected to unfavorable thermal conditions. However, according to some studies, shading can potentially worsen herds´ parasitism due to better microclimatic condition for the parasites. This study aimed to assess fecal egg count in Nellore heifers reared in two silvopastoral arrangements (pasture with single or triple tree rows), in a crop-livestock system, and open pasture. In the silvopastoral treatment composed of triple rows, lesser parasite burden means were found, with a peak infection in February/March and another in October. Regarding the effect of seasons over the year, there was an environmental influence on the egg counts, with higher averages during the late rainy season and the beginning of the dry season. An immunological investigation of animals from each group showed that cattle kept on the silvopastoral arrangements with either single or triple rows have significantly higher lymphocyte proliferation when stimulated with specific antigens than those kept on open pastures. Based on our results, it can be concluded that both silvopastoral systems were not considered as a risk factor for nematode egg counts in Nellore heifers. Indeed, the shadiest system promoted milder parasitism and higher immunological lymphocyte responses in animals.

Positivity Rate Investigation and Anthelmintic Resistance Analysis of Gastrointestinal Nematodes in Sheep and Cattle in Ordos, China

Simple Summary

In order to understand the positivity rates of gastrointestinal nematodes in cattle and sheep in Ordos, and the effects of different pasture types on the distribution of gastrointestinal nematodes, we conducted an epidemiological investigation and analysis in four banner districts of Ordos. The results showed that the positive rates of sheep and cattle were 38.84% and 4.48%, respectively. The anthelmintic resistance analysis revealed that the nematode population in the area was severely resistant to ivermectin and albendazole, and resistance to levamisole, nitroxynil and closantel was suspected.

Abstract

Gastrointestinal nematodes (GINs), such as Trichostrongylidae, are important pathogens in small ruminants, causing significant losses in these livestock species. Despite their veterinary importance, GINs have not been studied in certain regions of the world. Therefore, much of their epidemiology and economic impact on production remain unknown. In the present study, a systematic epidemiological survey based on the modified McMaster technique was conducted to investigate the type and infection of GINs in sheep and cattle. In 9622 fecal samples from 491 sampling sites in the four main banner districts of Ordos, the prevalence of GIN infection was found to be 38.84% and 4.48% in sheep and cattle, respectively. At the same time, the effects of four pasture types on the distribution of GINs were analyzed. This study also found severe resistance to ivermectin and albendazole in GINs and suspected anthelmintic resistance in nitroxynil, levamisole and closantel. We report the type and infection of GINs in Ordos, with the aim to help the prevention and control of GINs. Based on the results of the questionnaire survey and GIN resistance test, we found several reasons for the anthelmintic resistance of GINs, consequently providing new ideas for controlling the occurrence of anthelmintic resistance.

Local immune response of Canarian Majorera goats infected with Teladorsagia circumcincta

BACKGROUND

Due to increased anthelmintic resistance, alternative methods to drugs are necessary to control gastrointestinal nematodes (GINs). Some of the most promising alternatives are based on the immune response of the host, such as the selection of genetically resistant breeds or the use of vaccines against these parasites. Given the limited information available on the immune response against GINs in goats, this study investigated the local immune response of goat kids of an indigenous Canary Islands breed (Majorera breed) experimentally infected with Teladorsagia circumcincta, one of the most pathogenic and prevalent GIN species.

METHODS

For this purpose, the relationship between different parasitological (number of mature and immature worms, worm length, and number of intrauterine eggs) and immunological parameters at the local level (related to both the humoral and cellular immune response) was analyzed at early (1 week post-infection [wpi]) and late (8 wpi) stages of infection.

RESULTS

Primary infection of goat kids with T. circumcincta infective larvae (L3) generated a complex immune response that could be defined as Th2 type, characterized by increased infiltration in abomasal tissues of several effector cells as well as a progressive presence of specific antibodies against parasitic antigens in the gastric mucus. Cellular responses were evidenced from 1 wpi onward, showing an increase in antigen-presenting cells and various lymphocyte subsets in the gastric mucosa.

CONCLUSIONS

The complexity of the host response was evidenced by statistically significant changes in the number of all these subpopulations (MHCII⁺, CD4⁺, CD8⁺, γδ⁺, CD45R⁺, IgA⁺, and IgG⁺), as well as in the evolution of the relative cytokine gene expression. From a functional point of view, negative associations were observed between the number of most of the immune cells (CD4, IgA, IgG, and CD45R cells) and parameters that could be related to the fecundity of worms, a phenomenon that was especially evident when the number of IgG and CD45R cells or the specific IgA levels of the gastric mucus were compared with parasitological parameters such as the female worm length or fecal egg counts at 8 wpi.

Risk and protection strategies of Amolops wuyiensis intestine against gastrointestinal nematode (Cosmocercoides wuyiensis n. sp.) infection

Anuran amphibians are susceptible to infection by intestinal nematodes, but the damage and response mechanisms that occur in their intestines after infection are only partially understood. In this study, the intestinal disruption and response mechanisms in Amolops wuyiensis frogs infected with Cosmocercoides wuyiensis n. sp. were revealed through analysis of the intestinal histopathology, digestive enzyme activity, transcriptome and intestinal microbiota. Tissue section analysis showed histological damage and inflammation in the infected intestine, and the digestive enzyme activity indicated a decrease in digestion and absorption of some nutrients. We found that infection led to differences in the intestinal microbiota composition, including lower diversity and symbiotic relationships. The greater relative abundance of the genera Burkholderia and Rhodococcus may enhance intestinal immunity to resist pathogenic infections. A comparison of the transcriptomes of infected and uninfected intestines revealed 1055 differentially expressed genes. GO enrichment and KEGG pathways analyses suggested that the guts of infected C. wuyiensis n. sp. show enhanced complement activation, cell adhesion molecule function, NOD-like receptor signalling pathway activity and other innate immunity responses. Among the adaptive immune responses, the intestinal immune network for IgA production was significantly enriched, and the expression of IL-17D and transforming growth factor beta-1 genes were upregulated in the infected intestine. These results imply that C. wuyiensis n. sp. infection of A. wuyiensis intestine may trigger innate and adaptive immune responses, which reduce the post-infection burden. Furthermore, the intestine of A. wuyiensis may also respond to C. wuyiensis n. sp. infection by increasing metallocarboxypeptidase activity and accelerating smooth muscle contraction.

Gastrointestinal nematode and Eimeria spp. infections in dairy cattle along a rural-urban gradient

Endoparasite infections can lead to considerable economic losses in dairy cattle due to decreases in milk yield and quality. Environmental and host-related factors contribute to endoparasite infection intensity and probability. Moreover, advancing urbanization influences parasite infection dynamics in livestock due to close human-animal cohabitation and changes in animal housing conditions. The aim of the present study was to investigate social-ecological effects on gastrointestinal nematode (GIN) and Eimeria spp. infections in dairy cattle along a rural-urban gradient in the emerging Indian megacity Bangalore. In this regard, 726 faecal samples from 441 dairy cattle of different ages and physiological stages were collected from 101 farms and examined at three visits between June 2017 and April 2018. Based on a survey stratification index (SSI) comprising built-up density and distance to the city center, we assigned the farms to urban, mixed and rural areas. GIN eggs were identified in the faeces of 243 cattle (33.5%; 95% confidence interval [CI]: 30.1-36.9%), and Eimeria spp. oocysts in the faeces of 151 cattle (20.8%; 95% CI: 17.9-23.7%). Co-infection rates of GIN and Eimeria spp. were 8.5 to 12.2% higher in rural compared to urban and mixed areas. The SSI effect significantly influenced Eimeria spp. infection probability and oocyst per gram of faeces (OpG; P < 0.001) with an infection probability and OpG higher than 26% and 40% for cattle kept in rural areas compared to cattle from urban areas. However, the SSI effect was not significant for the infection probability of GIN and for GIN eggs per gram of faeces (EpG). Infection probabilities and EpG/OpG were significantly higher in calves and heifers compared to lactating and dry cows. Moreover, we estimated significantly lower OpG values in summer compared to the other seasons. No differences were estimated for GIN and Eimeria spp. infection probabilities and EpG/OpG with regard to pasture access and breed. The variations in endoparasite infection intensity and probability observed along the rural-urban gradient of Bangalore reflect the variability in dairy husbandry systems governed by the social-ecological context.

A Review of the Neutrophil Extracellular Traps (NETs) from Cow, Sheep and Goat Models

This review provides insight into the importance of understanding NETosis in cows, sheep, and goats in light of the importance to their health, welfare and use as animal models. Neutrophils are essential to innate immunity, pathogen infection, and inflammatory diseases. The relevance of NETosis as a conserved innate immune response mechanism and the translational implications for public health are presented. Increased understanding of NETosis in ruminants will contribute to the prediction of pathologies and design of strategic interventions targeting NETs. This will help to control pathogens such as coronaviruses and inflammatory diseases such as mastitis that impact all mammals, including humans. Definition of unique attributes of NETosis in ruminants, in comparison to what has been observed in humans, has significant translational implications for one health and global food security, and thus warrants further study.

Analysis of the immunomodulatory activity of excreted and secreted products from Haemonchus placei transition infective larvae (xL3)

The excretory/secretory (E/S) products released by infective transitory larvae (xL₃) of Haemonchus placei have an important biological function in stimulating immune mechanisms during the invasive process. Our objective was to analyse the modulatory activity of 15 and 70 kDa E/S products from H. placei xL₃. Both E/S products were collected from xL₃in vitro cultures at 24 and 72 h. Proteins were confirmed by SDS-PAGE, and the corresponding spots were elicited by gel isoelectrofocusing (IEF) and characterised by mass spectrometry. Additionally, flow cytometry of CD4⁺/γδ⁺ T cells and immune gene expression were performed by proliferation assays using each E/S product to stimulate lymphocyte and peripheral blood mononuclear cells (PBMCs) from non-infected calves. The IEF results displayed two spots of 7.0 and 5.7 pI for the 15 and 70 kDa products, respectively. Additionally, 29 and 17 peptides from the 15 and 70 kDa E/S products, respectively, were identified with the hypothetical neurotransmitter and enzymatic functions necessary for larval development. The relative expression displayed upregulation of IL4, 5, 6, 8, 10, 13, IFNγ, and FCεR1A genes (from 2.0- to 17.6-fold, p < 0.05) stimulated by the 15 and 70 kDa proteins, indicating specific genes against haemonchosis. Although the percentage of median florescence intensity (MFI%) of CD4⁺/γδ⁺ T cells did not change for both E/S products compared to the negative control and concanavalin-A stimulated cells as the positive control (p > 0.05), the 15-kDa protein reduced the levels of both T cells, and the 70-kDa proteins increased the γδ⁺ cells slightly. Additionally, there was increased PBMCs proliferation by the 70 kDa proteins (p < 0.05), denoting the biological role of other immune cells. The 15 and 70 kDa protein E/S products from H. placei xL₃ showed modulation of the immune response, and although more studies are required, they indicate important functions in the host/parasite interaction.

Repeated, drug-truncated infections with Ostertagia ostertagi elicit strong humoral and cell-mediated immune responses and confer partial protection in cattle

Bovine ostertagiasis causes significant production losses to the cattle industry. Protective immunity induced by natural infection is slow to develop and anthelmintic resistance is rapidly developing. There is a need to advance alternatives for control of gastrointestinal nematode parasites. The present study investigated the effects of repeated, drug-truncated infections (rDTI) on development of protective immunity and attenuation of a challenge infection by O. ostertagi. Helminth-free calves were randomly assigned to either a rDTI or a control group (n = 5). The rDTI group received daily oral infections of 5000 Ostertagia L3 for 5 consecutive days, then were drug-treated on 14 and 15 days post infection (dpi), to attenuate O. ostertagi at the late fourth larval (L4) through young adult stages. DTI was repeated 3 weeks after the drug treatment. A total of 5 DTIs were administered to the DTI-treated animals. Non-DTI-treated, control animals received tap water as infection control. All animals were drug-treated at the same time. Animals were challenge-infected 4 weeks following the final round of rDTI. The results show that eggs per gram of feces (EPG) in the rDTI group were significantly reduced (P < 0.05) from 21 to 39 dpi, with an overall reduction in cumulative EPG. The control group exhibited reduced (P = 0.0564) average weight gains when compared to those of the rDTI group during weeks 4-5 post infection, a period coinciding with peak EPG output of control animals. Antigen-specific IgG, IgE and IgA responses were detected after the 2nd DTI, and stronger antibody recall responses were elicited by challenge infection. High levels of antigen-specific peripheral blood mononuclear cell (PBMC)/T cell proliferation to whole worm and excretory-secretory (ES) antigens were detected in rDTI-treated animals. These data indicate that partial protective immunity against ostertagiasis, involving cell-mediated and humoral responses, can be attained by rDTI which allowed for maximal antigen exposure from staggered parasitic developmental stages. The data suggest that rDTI can be used as a model to study host-parasite interactions and identify parasite antigens responsible for eliciting host protective immune responses.

Increased epithelial galectin-13 expression associates with eosinophilic airway inflammation in asthma

BACKGROUND

Airway eosinophilic inflammation is a central feature in asthma which is mainly driven by type 2 response. The expression of galectin-13 was up-regulated in a parasitic infection model which is also characterized by type 2 immune response. We hypothesized that galectin-13 may be involved in airway eosinophilic inflammation in asthma.

OBJECTIVE

To unveil the role of galectin-13 in asthma airway inflammation.

METHODS

We measured galectin-13 expressions in bronchial brushings, sputum, and plasma of asthma patients (n = 54) and healthy controls (n = 15), and analysed the correlations between galectin-13 expression and airway eosinophilia. We used human bronchial epithelial cell line 16HBE to investigate the possible mechanism by which galectin-13 participates in eosinophilic inflammation.

RESULTS

The expression of galectin-13 was markedly increased in subjects with asthma compared to controls. Epithelial galectin-13 mRNA levels in asthmatic subjects were strongly correlated with eosinophilic airway inflammation (the percentage of sputum eosinophils, the number of eosinophils in bronchial submucosa and FeNO) and the expression of Th2 signature genes (CLCA1, POSTN and SERPINB2). Inhaled corticosteroid (ICS) treatment reduced plasma galectin-13 levels, and baseline plasma galectin-13 levels reflect the response to ICS treatment. In cultured 16HBE cells, knockdown of galectin-13 suppressed IL-13-stimulated MCP-1 and eotaxin-1 expression by inhibiting the activation of EGFR and ERK.

CONCLUSIONS & CLINICAL RELEVANCE

Galectin-13 is a novel marker for airway eosinophilia in asthma, and may contribute to allergic airway eosinophilic inflammation by up-regulating the expression of MCP-1 and eotaxin-1. Plasma galectin-13 levels may be useful for predicting responses to ICS treatment.

Genome-wide insights on gastrointestinal nematode resistance in autochthonous Tunisian sheep

Gastrointestinal nematode (GIN) infections have negative impacts on animal health, welfare and production. Information from molecular studies can highlight the underlying genetic mechanisms that enhance host resistance to GIN. However, such information often lacks for traditionally managed indigenous livestock. Here, we analysed 600 K single nucleotide polymorphism genotypes of GIN infected and non-infected traditionally managed autochthonous Tunisian sheep grazing communal natural pastures. Population structure analysis did not find genetic differentiation that is consistent with infection status. However, by contrasting the infected versus non-infected cohorts using ROH, LR-GWAS, F_ST and XP-EHH, we identified 35 candidate regions that overlapped between at least two methods. Nineteen regions harboured QTLs for parasite resistance, immune capacity and disease susceptibility and, ten regions harboured QTLs for production (growth) and meat and carcass (fatness and anatomy) traits. The analysis also revealed candidate regions spanning genes enhancing innate immune defence (SLC22A4, SLC22A5, IL-4, IL-13), intestinal wound healing/repair (IL-4, VIL1, CXCR1, CXCR2) and GIN expulsion (IL-4, IL-13). Our results suggest that traditionally managed indigenous sheep have evolved multiple strategies that evoke and enhance GIN resistance and developmental stability. They confirm the importance of obtaining information from indigenous sheep to investigate genomic regions of functional significance in understanding the architecture of GIN resistance.

Haemonchus contortus infection induces a variable immune response in resistant and susceptible Pelibuey sheep

The immune response and phenotypic characteristics of Pelibuey lambs were analysed after the induction of a Haemonchus contortus trickle infection. Male lambs (n = 29; 20 kg live weight) were infected with 100 H. contortus infective larvae per kg of live weight on day 3, 5 and 7 of the experiment. The number of eggs per gram (epg), seven haematological parameters and the immunoglobulin A (IgA) level were analysed for 56 experimental days. In addition, histopathological samples from the fundic abomasal region and the relative expression of 10 immune-related genes from 15 infected and three non-infected lambs were analysed at day 0 and 49 of the experiment. The epg count and some haematological parameters (leucocytes, red blood cells, haemoglobin and total protein) with statistically significant differences (P < 0.01) were used to identify nine resistant and 20 susceptible lambs (1166 ± 1071 and 3171 ± 1463 epg, respectively). Moreover, acute infiltration of immune cells and parasitic granuloma formation were observed in susceptible lambs; the resistant group had moderate inflammatory cell infiltration. With respect to relative gene expression, resistant lambs showed upregulation (P < 0.001) of 10 genes, from 2.2 to 15.99 fold. Moreover, there was a strong indirect correlation (P < 0.05) between the epg count and interleukin 5 (IL5) gene expression. By contrast, there was an average 0.34 fold downregulation in nine of the immune-related genes (P ≤ 0.05) in susceptible lambs (the only exception was Fc fragment of IgE receptor Ia [FCER1A] upregulation). In addition, there was a direct correlation (P ≤ 0.05) between the epg count and the expression of IL8, which encodes an inflammatory chemokine. In conclusion, this study showed differential IL5 and IL8 gene expression during haemonchosis in resistant and susceptible Pelibuey lambs, respectively, together with a variable immune response based on histopathological and haematological parameters.

Gastrointestinal parasites of a reintroduced semi-wild plains bison (Bison bison bison) herd: Examining effects of demographic variation, deworming treatments, and management strategy

Bison (Bison spp) are being reintroduced into semi-wild, spatially constrained herds across North America and Europe. Herd managers are concerned about gastrointestinal (GI) nematode parasites as they care for the health of their bison. We examine how demographics, grazing location, herd management, and anthelmintic treatments affect the fecal egg counts (FECs) of GI nematodes within a reintroduced Plains bison (Bison bison bison) herd in the Great Plains. Our results suggest that younger bison (<2 years of age) experience higher GI parasite eggs/oocysts per gram (epg/opg) and that some taxa are more prevalent throughout different periods of a bison's early years. Demographic findings suggest that calf and yearling (0–2 yrs age) bison have the highest FECs and that these decline until reaching a low in peak adulthood and thereafter (x > 6 yrs of age). FECs of both Trichuris spp. and particularly Nematodirus spp. were much more abundant, relatively, during the first year of a bison's life. This pattern was also true of Moniezia spp. and Eimeria spp., however, strongyle-type spp. FECs appeared to peak in relative abundance during the second year of life. Our data also indicate that FECs are influenced by differences in land-use histories of pastures previously grazed by cattle or by the proportion of frequent flooding in different pastures. Treatment results suggest that fenbendazole may more effective than moxidectin at lowering FECs of bison over the long-term, and lasting effects of at least one administered anthelmintic treatment. Multiplex PCR assays revealed that American bison share GI nematodes with cattle including: Ostertagia spp., Haemonchus placei, Cooperia onchophora, and Oesophagostomum spp, but did not detect the presence Trichostrongylus columbriformis. Our results may have wider conservation implications for reintroduction efforts of American bison, as well as the endangered European bison (Bison bonasus).

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Younger plains bison (<2 years of age) are more likely to have higher fecal egg counts of gastrointestinal nematodes.

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Eimeria spp., Trichuris spp., Moniezia spp., and Nematodirus spp. are more prevalent in plains bison between zero and 1 years of age, while strongyle-type nematodes are more prevalent in bison between 1 and 2 years of age.

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Both land-use histories and landscape features may influence higher fecal egg counts of gastrointestinal nematodes in plains bison.

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Plains bison share many of the same type of gastrointestinal parasites found in cattle.

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Fenbendazole anthelmintic was more effective than moxidectin treatments in reducing fecal egg counts of gastrointestinal parasites in plains bison.

The immune gene expression induced by Cooperia punctata in naturally infected calves with resistance and susceptible phenotype traits

The analysis of the immune gene expression was performed in Zebu × Holstein calves with resistant and susceptible phenotypes naturally infected with Cooperia punctata. Fourteen calves of 4 months old were grazed for 11 weeks under a tropical climate. The parasitic infection showed an average epg value of 1055 ± 1155 and an IgG optical density of 0.814 ± 0.0.037 with statistic differences among the different weeks (p < 0.05), and a pcv value of 24 ± 2.0 % (p > 0.05). High variation in epg value was observed, between 7 ± 7.14 and 4657 ± 1886, and, based on these differences; the infected hosts were classified as five resistant calves with epg ≤ 200 and nine susceptible calves with epg ≥ 300. Moreover, IgG levels displayed statistical differences between resistance and susceptible calves to C. punctata infection. The immune gene expression was analysed in three resistant and susceptible calves, respectively. Nine cytokine genes and the FCεR1A receptor were analysed at the 3rd and 11th weeks post-infection. In the first period upregulation was found, from 2.19- to 9.45-fold, (p < 0.05) for IL-2, -5, - 6, -10, TGF-β and FCεR1A in the resistant group; the expression was decreased at the 11th week with low level of IgG. In contrast, downregulation for susceptible calves was found for nine immune genes and upregulation for INF-γ in both periods together with increased IgG levels. In conclusion, immune gene expression was regulated at the begging infection of C. punctata in resistant grazing calves. In contrast, suppression of important genes was involved in calves susceptible to C. punctata.

Rainfall as a driver of seasonality in parasitism

Parasite burdens are known to vary seasonally in wildlife, and rainfall is one key aspect of seasonality that has been linked to parasitism in a range of systems. Rainfall can have immediate effects on parasitism rates by affecting parasite survival and movement in the environment, or it can have delayed effects by affecting host susceptibility to parasites through changes in host body condition or immune function. In this study, we examined how helminth infection in a wild ungulate (Grant's gazelle, Nanger granti) is impacted by seasonal changes in rainfall. We looked at how the burdens of three helminth parasites varied in relation to current (immediate effect) and prior (delayed effect) rainfall by comparing parasite fecal egg and larval counts to rainfall 0, 1, and 2 months prior to parasite sampling. We found burdens of all three parasites to be negatively associated with rainfall, and that delayed effects were stronger than immediate effects. Our findings implicate rainfall as a driver of seasonal variation in infection and suggest one important mechanism may be through delayed effects on host susceptibility.

Sustainable Approaches to Parasite Control in Ruminant Livestock

It is increasingly difficult to manage and control gastrointestinal nematode parasites in pasture-based ruminant livestock operations because of the high prevalence of anthelmintic resistance. Anthelmintics should be combined with alternative forms of control. Sustainable tools include copper oxide wire particles and condensed tannin-rich plants, which target primarily Haemonchus contortus in small ruminants. Nematophagous fungi reduce larvae on pasture and target nematode larvae in feces of most livestock species. In addition, and perhaps most importantly, genetic selection focuses on parasite resistance. Producers should use as many tools as possible to minimize the need for pharmaceutical interventions and optimize animal production.

Biology and Epidemiology of Gastrointestinal Nematodes in Cattle

This article reviews the basics of gastrointestinal nematode biology and pathophysiology in cattle and describes how gastrointestinal nematode epidemiology is driven by environmental, host, and farm economic determinants. Adverse effects from gastrointestinal nematodes on their hosts are caused by tissue damage, nutrient absorption, immunopathologic effects, and reduced food intake induced by hormonal changes. Weather and microenvironmental factors influence the development and survival of free-living parasitic stages. A holistic control approach entails the consideration of environmental, immunologic, and socioeconomic aspects of nematode epidemiology and is key for the development and communication of sustainable control strategies.

Characterization of IL-10-producing neutrophils in cattle infected with Ostertagia ostertagi

IL-10 is a master regulator of immune responses, but its cellular source and function in cattle during the initial phase of immune priming have not been well established. Despite a massive B cell response in the abomasal draining lymph nodes in Ostertagia ostertagi (OO)-infected cattle, protective immunity is slow to develop, and partial protection requires years of repeated exposure. In addressing this problem, our initial hypothesis was that B cells produce IL-10 that downregulates the host protective immune response. However, our results showed that neutrophils made up the majority of IL-10-producing cells in circulation and in secondary lymphoid tissues, particularly the spleen (80%). Conversely, IL-10-producing B cells were rare. In addition, approximately 10% to 20% of the neutrophils in the blood and spleen expressed MHC II and were IL-10 negative, suggesting that neutrophils could also participate in antigen presentation. In vitro investigation of bovine neutrophils revealed that exposure thereof to OO extract increased IL-10 and MHC II expression in these cells in a dose-dependent manner, consistent with IL-10+/MHC II+ neutrophils detected in cattle shortly after experimental OO infection. Co-culture of untreated neutrophils with anti-CD3 antibody (Ab)-stimulated CD4+ T cells led to enhanced T cell activation; also, IL-10 depletion with neutralizing Ab enhanced the stimulatory function of neutrophils. OO extract depressed neutrophil stimulation of CD4+ T cells in the presence of IL-10-neutralizing Ab, suggesting that OO utilizes both IL-10-dependent and independent mechanisms to manipulate the bovine immune response. Finally, contact and viability were required for T cell-stimulatory neutrophil function. This report, to the best of our knowledge, is the first to demonstrate that neutrophil-derived IL-10 is directly involved in T cell regulation in cattle. Our data suggest that neutrophils and neutrophil-derived IL-10 are co-opted by nematode parasites and other pathogens to attenuate host immune responses and facilitate pathogen survival.

Genome-wide associations and functional gene analyses for endoparasite resistance in an endangered population of native German Black Pied cattle

Background

Gastrointestinal nematodes (GIN), liver flukes (Fasciola hepatica) and bovine lungworms (Dictyocaulus viviparus) are the most important parasitic agents in pastured dairy cattle. Endoparasite infections are associated with reduced milk production and detrimental impacts on female fertility, contributing to economic losses in affected farms. In quantitative-genetic studies, the heritabilities for GIN and F. hepatica were moderate, encouraging studies on genomic scales. Genome-wide association studies (GWAS) based on dense single nucleotide polymorphism (SNP) marker panels allow exploration of the underlying genomic architecture of complex disease traits. The current GWAS combined the identification of potential candidate genes with pathway analyses to obtain deeper insights into bovine immune response and the mechanisms of resistance against endoparasite infections.

Results

A 2-step approach was applied to infer genome-wide associations in an endangered dual-purpose cattle subpopulation [Deutsches Schwarzbuntes Niederungsrind (DSN)] with a limited number of phenotypic records. First, endoparasite traits from a population of 1166 Black and White dairy cows [including Holstein Friesian (HF) and DSN] naturally infected with GIN, F. hepatica and D. viviparus were precorrected for fixed effects using linear mixed models. Afterwards, the precorrected phenotypes were the dependent traits (rFEC-GIN, rFEC-FH, and rFLC-DV) in GWAS based on 423,654 SNPs from 148 DSN cows. We identified 44 SNPs above the genome-wide significance threshold (p_Bonf = 4.47 × 10^− 7), and 145 associations surpassed the chromosome-wide significance threshold (range: 7.47 × 10^− 6 on BTA 1 to 2.18 × 10^− 5 on BTA 28). The associated SNPs identified were annotated to 23 candidate genes. The DAVID analysis inferred four pathways as being related to immune response mechanisms or involved in host-parasite interactions. SNP effect correlations considering specific chromosome segments indicate that breeding for resistance to GIN or F. hepatica as measured by fecal egg counts is genetically associated with a higher risk for udder infections.

Conclusions

We detected a large number of loci with small to moderate effects for endoparasite resistance. The potential candidate genes regulating resistance identified were pathogen-specific. Genetic antagonistic associations between disease resistance and productivity were specific for specific chromosome segments. The 2-step approach was a valid methodological approach to infer genetic mechanisms in an endangered breed with a limited number of phenotypic records.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5659-4) contains supplementary material, which is available to authorized users.

Immune response against subclinical haemonchosis in Himalayan hill goats

Haemonchosis commonly occurs as chronic and subclinical infection in small ruminants, and understanding of immunological response against subclinical haemonchosis is of paramount importance for designing and implementing effective control strategies. The present study was designed to evaluate immunological response during subclinical haemonchosis, experimentally established in goats. Sixteen 5-6 month-old helminth naive kids were randomly allocated into one of two groups, infected and uninfected; the infected group being infected per os with 250 Haemonchus contortus larvae per kg body weight. Faecal, blood and serum samples were collected every third day up to 30 days post-infection (DPI), thereafter weekly up to 58 DPI to record changes in faecal egg count (FEC), haemoglobin (Hb), packed cell volume (PCV), peripheral eosinophil percentage and immunological parameters, such as macrophage cytokine interleukin-12 (IL-12), Th1 cytokine (IFN-γ), Th2 cytokines (IL-4, 13, 25, 33) and immunoglobulins (IgG and IgE). Pre-patent period of H. contortus in the present study was 18 days and eggs per gram (EPG) peaked on 30 DPI. The total reduction in body weight gain in the infected group was 26 g per day when compared with uninfected animals. Hb (7.35 ± 0.34 g/dL in infected animals compared with 9.76 ± 0.67 in control animals) and PCV levels (22 ± 1.54 g/dL in infected animals compared with 29.2 ± 1.27 in control animals) decreased significantly up to 44 DPI in infected group (P = 0.000). IL-4, IL-13, IL-33, IgG and IgE showed significant increase in infected animals at different periods. IFN-γ, IL-12 and IL-25 did not show any significant changes barring a steep rise of IFN-γ on 27 DPI. A positive correlation was observed between IgE and IL-4 in subclinical haemonchosis. Of particular note was that all the major cytokines, such as IFN-γ (P = 0.000), IL-4 (P = 0.000), IL-13 (P = 0.009), and both IgG (P = 0.000) and IgE (P = 0.003), were observed at the lowest concentration on 24 DPI. The effect of infection was found to be significant on cytokines with a strong interaction with time. Taken together, the data suggest that Th2 immune response is predominating in subclinical haemonchosis. The economic loss in term of body weight gain due to subclinical haemonchosis was considerable.

Bovine Neonatal Monocytes Display Phenotypic Differences Compared With Adults After Challenge With the Infectious Abortifacient Agent Neospora caninum

The neonatal period represents a window of susceptibility for ruminants given the abundance of infectious challenges in their environment. Maternal transfer of immunity does not occur in utero but post-parturition, however this does not compensate for potential deficits in the cellular compartment. Here we present a cellular and transcriptomic study to investigate if there is an age-related difference in the monocyte response in cattle during intra-cellular protozoan infection. We utilized Neospora caninum, an obligate intracellular protozoan parasite that causes abortion and negative economic impacts in cattle worldwide, to study these responses. We found neonatal animals had a significant greater percentage of CD14⁺ monocytes with higher CD80 cell surface expression. Adult monocytes harbored more parasites compared to neonatal monocytes; additionally greater secretion of IL-1β was observed in neonates. Microarray analysis revealed neonates have 535 genes significantly upregulated compared to adult with 23 upregulated genes. Biological pathways involved in immune response were evaluated and both age groups showed changes in the upregulation of tyrosine phosphorylation of STAT protein and JAK-STAT cascade pathways. However, the extent to which these pathways were upregulated in neonates was much greater. Our findings suggest that neonates are more resistant to cellular invasion with protozoan parasites and that the magnitude of the responses is related to significant changes in the JAK-STAT network.

Immunity to gastrointestinal nematodes in ruminants: effector cell mechanisms and cytokines

Gastrointestinal nematodes (GINs) of ruminants are prevalent and have major economic impacts worldwide. The insight studies of immune responses triggered against GINs are of great concern to understand interaction between host's immune system and parasite. T-helper 2 cytokines drive the effector cell mechanisms which include eosinophils and mast cells. The immune responses are controlled by Th2 secreted interleukins (IL); IL3, IL-4, IL-5, IL-9, IL-10 and IL-13. B-Cell immune response is incorporated in defense mechanisms developed against GINs specially immunoglobulins (Ig); IgA, IgE and IgG. The immune resistance of the infected host is presented by failure of larval establishment or hypobiosis, low worm burden and decreased female fecundity. The host-parasite interaction is a complex series that affected by host's genetic constitution, nutrition, age and physiological status. The GINs have different immune evasion mechanisms to improve their survival within the host. Also, management of the host influences GINs parasitism. Thus, the aim of this review is to highlight the hallmarks of immune responses that endorse GINs parasitism. The insights studies of the triggered immune responses developed against GINs will improve the appropriate protective immune strategy.

Mucus-Pathogen Interactions in the Gastrointestinal Tract of Farmed Animals

Gastrointestinal infections cause significant challenges and economic losses in animal husbandry. As pathogens becoming resistant to antibiotics are a growing concern worldwide, alternative strategies to treat infections in farmed animals are necessary in order to decrease the risk to human health and increase animal health and productivity. Mucosal surfaces are the most common route used by pathogens to enter the body. The mucosal surface that lines the gastrointestinal tract is covered by a continuously secreted mucus layer that protects the epithelial surface. The mucus layer is the first barrier the pathogen must overcome for successful colonization, and is mainly composed of densely glycosylated proteins called mucins. The vast array of carbohydrate structures present on the mucins provide an important setting for host-pathogen interactions. This review summarizes the current knowledge on gastrointestinal mucins and their role during infections in farmed animals. We examine the interactions between mucins and animal pathogens, with a focus on how pathogenic bacteria can modify the mucin environment in the gut, and how this in turn affects pathogen adhesion and growth. Finally, we discuss analytical challenges and complexities of the mucus-based defense, as well as its potential to control infections in farmed animals.

High species diversity of trichostrongyle parasite communities within and between Western Canadian commercial and conservation bison herds revealed by nemabiome metabarcoding

Background

Many trichostrongylid nematode species are reported to infect bison, some of which are major causes of disase and production loss in North American bison herds. However, there is little information on the species distribution and relative abundance of these parasites in either commercial or conservation herds. This is largely because trichostrongylid nematode species cannot be distinguished by visual microscopic examination of eggs present in feces. Consequently, we have applied ITS2 rDNA nemabiome metabarcoding to describe the trichostrongyle parasite species diversity in 58 bison production groups derived from 38 commercial North American plains bison (Bison bison bison) herds from across western Canada, and two bison conservation herds located in Elk Island National Park (EINP) [plains bison and wood bison (Bison bison athabascae)] and one in Grasslands National Park (GNP) (plains bison).

Results

We report much higher infection intensities and parasite species diversity in commercial bison herds than previously reported in beef cattle herds grazing similar latitudes. Predominant trichostrongyle parasite species in western Canadian commercial bison herds are those commonly associated with Canadian cattle, with Ostertagia ostertagi being the most abundant followed by Cooperia oncophora. Combined with high fecal egg counts in many herds, this is consistent with significant clinical and production-limiting gastrointestinal parasitism in western Canadian bison herds. However, Haemonchus placei was the most abundant species in five of the production groups. This is both surprising and important, as this highly pathogenic blood-feeding parasite has not been reported at such abundance, in any livestock species, at such northerly latitudes. The presence of Trichostrongylus axei as the most abundant parasite in four herds is also unusual, relative to cattle. There were striking differences in parasite communities between the EINP and commercial bison herds. Most notably, Orloffia bisonis was the predominant species in the wood bison herd despite being found at only low levels in all other herds surveyed.

Conclusions

This study represents the most comprehensive description of parasite communities in North American bison to date and illustrates the power of deep amplicon sequencing as a tool to study species diversity in gastrointestinal nematode communities.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2880-y) contains supplementary material, which is available to authorized users.

Patent gastrointestinal nematode infections in organically and conventionally pastured dairy cows and their impact on individual milk and fertility parameters

Infections with gastrointestinal nematodes (GIN) can lead to production losses and impacts on product quality in affected cows, which has mainly been demonstrated during deworming experiments or via herd-level measurements. Here, a field study was carried out to explore the association between GIN infection status and milk production as well as fertility parameters in individual dairy cows. Different selection lines of Black and White cows were included in the study, which were distributed among 17 small and medium-sized organic and conventional German grassland farms. Faecal samples of 1166 dairy cows were examined twice, in July and September 2015. Nematode eggs were found in the faeces of 473 (40.6%) cows. As expected, strongylid eggs (Trichostrongylidae or Oesophagostomum and Bunostomum spp., respectively) were the predominant morphotype, followed by Strongyloides papillosus and Capillaria spp. eggs. In July, cows kept under organic conditions had a significantly lower GIN prevalence in comparison to cows kept on conventional farms. Faecal egg counts were generally low, with the highest value in September and an arithmetic mean of 11.3 eggs per gram faeces (EPG) for all observations. The relationships between GIN infection status and milk yield (kg milk/cow/day), milk protein content (%) and milk fat content (%) for each first test-day record after parasitological assessment were estimated by using linear mixed models. Milk protein content was estimated 0.05% lower in GIN positive compared to GIN negative cows, whereas no significant effect on milk yield or milk fat content was observed. The impact of GIN infection status on success in first insemination (SFI) was estimated by using a threshold model. No significant association was demonstrated between GIN infection status and SFI. Unexpectedly, the fertility parameter days from calving-to-first-service (CTFS) showed a significantly shorter average interval in GIN positive cows. However, these data on reproductive performance need to be considered preliminary as long-term studies are needed to allow a firm prediction of the impact of GIN infection status on dairy cow fertility parameters.

Reciprocal relationships between behaviour and parasites suggest that negative feedback may drive flexibility in male reproductive behaviour

Parasites are ubiquitous components of the environment that contribute to behavioural and life-history variation among hosts. Although it is well known that host behaviour can affect parasite infection risk and that parasites can alter host behaviour, the potential for dynamic feedback between these processes is poorly characterized. Using Grant's gazelle (Nanger granti) as a model, we tested for reciprocal effects of behaviour on parasites and parasites on behaviour to understand whether behaviour-parasite feedback could play a role in maintaining variation in male reproductive behaviour. Adult male gazelles either defend territories to attract mates or reside in bachelor groups. Territoriality is highly variable both within- and between-individuals, suggesting that territory maintenance is costly. Using a combination of longitudinal and experimental studies, we found that individual males transition frequently between territorial and bachelor reproductive status, and that elevated parasite burdens are a cost of territoriality. Moreover, among territorial males, parasites suppress aspects of behaviour related to territory maintenance and defence. These results suggest that territorial behaviour promotes the accumulation of parasites in males, and these parasites dampen the very behaviours required for territory maintenance. Our findings suggest that reciprocal feedback between host behaviour and parasitism could be a mechanism maintaining variation in male reproductive behaviour in the system.

Genetic line comparisons and genetic parameters for endoparasite infections and test-day milk production traits

Keeping dairy cows in grassland systems relies on detailed analyses of genetic resistance against endoparasite infections, including between- and within-breed genetic evaluations. The objectives of this study were (1) to compare different Black and White dairy cattle selection lines for endoparasite infections and (2) the estimation of genetic (co)variance components for endoparasite and test-day milk production traits within the Black and White cattle population. A total of 2,006 fecal samples were taken during 2 farm visits in summer and autumn 2015 from 1,166 cows kept in 17 small- and medium-scale organic and conventional German grassland farms. Fecal egg counts were determined for gastrointestinal nematodes (FEC-GIN) and flukes (FEC-FLU), and fecal larvae counts for the bovine lungworm Dictyocaulus viviparus (FLC-DV). The lowest values for gastrointestinal nematode infections were identified for genetic lines adopted to pasture-based production systems, especially selection lines from New Zealand. Heritabilities were low for FEC-GIN (0.05-0.06 ± 0.04) and FLC-DV (0.05 ± 0.04), but moderate for FEC-FLU (0.33 ± 0.06). Almost identical heritabilities were estimated for different endoparasite trait transformations (log-transformation, square root). The genetic correlation between FEC-GIN and FLC-DV was 1.00 ± 0.60, slightly negative between FEC-GIN and FEC-FLU (-0.10 ± 0.27), and close to zero between FLC-DV and FEC-FLU (0.03 ± 0.30). Random regression test-day models on a continuous time scale [days in milk (DIM)] were applied to estimate genetic relationships between endoparasite and longitudinal test-day production traits. Genetic correlations were negative between FEC-GIN and milk yield (MY) until DIM 85, and between FEC-FLU and MY until DIM 215. Genetic correlations between FLC-DV and MY were negative throughout lactation, indicating improved disease resistance for high-productivity cows. Genetic relationships between FEC-GIN and FEC-FLU with milk protein content were negative for all DIM. Apart from the very early and very late lactation stage, genetic correlations between FEC-GIN and milk fat content were negative, whereas they were positive for FEC-FLU. Genetic correlations between FEC-GIN and somatic cell score were positive, indicating similar genetic mechanisms for susceptibility to udder and endoparasite infections. The moderate heritabilities for FEC-FLU suggest inclusion of FEC-FLU into overall organic dairy cattle breeding goals to achieve long-term selection response for disease resistance.

Exploring the Genetic Resistance to Gastrointestinal Nematodes Infection in Goat Using RNA-Sequencing

Gastrointestinal nematodes (GINs) are one of the most economically important parasites of small ruminants and a major animal health concern in many regions of the world. However, the molecular mechanisms of the host response to GIN infections in goat are still little known. In this study, two genetically distinct goat populations, one relatively resistant and the other susceptible to GIN infections, were identified in Yichang goat and then four individuals in each group were chosen to compare mRNA expression profiles using RNA-seq. Field experiment showed lower worm burden, delayed and reduced egg production in the relatively resistant group than the susceptible group. The analysis of RNA-seq showed that 2369 genes, 1407 of which were up-regulated and 962 down-regulated, were significantly (p < 0.001) differentially expressed between these two groups. Functional annotation of the 298 genes more highly expressed in the resistant group yielded a total of 46 significant (p < 0.05) functional annotation clusters including 31 genes (9 in innate immunity, 13 in immunity, and 9 in innate immune response) related to immune biosynthetic process as well as transforming growth factor (TGF)-β, mitogen-activated protein kinase (MAPK), and cell adhesion molecules (CAMs) pathways. Our findings provide insights that are immediately relevant for the improvement of host resistance to GIN infections and which will make it possible to know the mechanisms underlying the resistance of goats to GIN infections.

Study of gastrointestinal parasites in water buffalo (Bubalus bubalis) reared under Mexican humid tropical conditions

The objective was to determine the frequency of gastrointestinal parasites (GP) genera affecting water buffalo (Bubalus bubalis) reared under humid tropical conditions of Mexico. Three hundred eighty-three Munrah breed water buffalo were included, 251 adult females and 132 calves. Feces were directly collected form the rectum of the animals and processed by the McMaster technique. Coprocultures were made to identify the genera of the nematodes. The frequency of GP in B. bubalis was 42%, independently of their age, 60% of calves resulted parasitized. Age had a strong association with the presence of GP (Xi² = 77.4014, d.f. = 1, p = 0.001). The family Trichostrongylidae was found in both age groups. The genera identified were Strongyloides sp. (47.2%), Cooperia sp. (33.9%), and Haemonchus sp. (10.4%), as well as Eimeria sp., Moniezia sp., Trichuris sp., and Strongyloides sp. The highest parasite burden corresponded to the genus Strongyloides sp. with 1108.9 EPG. There is a need to carry out further studies in order to know the prevalence and incidence of nematode affecting to B. bubalis as an introduced animal species to Mexican tropics.

Survey of gastrointestinal parasites, liver flukes and lungworm in feces from dairy cattle in the high tropics of Antioquia, Colombia

A cross sectional study was undertaken to determine the prevalence and intensity of parasitic infections in dairy cattle in the high tropics of Colombia. A total of 1003 rectal samples were collected from dairy cows at 29 farms between May and June 2014 to represent the number of farms, age groups, and size of the 65,000-cow population in the municipality of San Pedro de los Milagros. Coprological techniques were used to detect gastrointestinal nematodes, liver flukes, coccidian oocysts, and first larval stage counts of Dictyocaulus viviparus. In order of decreasing prevalence, the following parasites were detected: coccidial oocyst (36.7%; 95% CIs, 31.6–42.7), strongyle nematodes (31.6%, 27.8–35.4), liver flukes (30.9%, 21.5–37.5), cestodes (8.4%, 7.1–9.7), and D. viviparus (5.4%, 3.4–7.5). Co-infections by all possible combinations of the three most predominant groups occurred in 11 to 15% of the animals. There were significant differences in infection rates between age groups, with higher risk of liver fluke infection in animals older than 1 year of age (odds ratio (OR) = 3.2), but lower presence for coccidia and strongyles (OR = 0.19 and 0.51, respectively). For Fasciola hepatica, within-herd prevalences of > 25% in 16 farms and 94 of 281 (33.5%) animals with > 5 eggs per gram (epg) indicate that significant production losses are likely occurring. The variation in the prevalence of gastrointestinal parasites and liver flukes, together with the level of infection among age groups, could be used in integrated management programs to establish selective anthelmintic treatments and select for heritable traits of host resistance. These results serve as a baseline for future studies to determine the success of control measures and should increase awareness that subclinical parasitism is widespread in the livestock sector.

A review of the epidemiology and control of gastrointestinal nematode infections in cattle in Zimbabwe

In this review, the main gastrointestinal nematodes infecting cattle in Zimbabwe and the epidemiological factors influencing their occurrence are reviewed and discussed. Nineteen gastrointestinal nematode species that belong to seven families have been found to occur in cattle in Zimbabwe. The main genera reported to date are Cooperia, Haemonchus, Trichostrongylus and Oesophagostomum and the dominant species are Cooperia pectinata, Cooperia punctata, Haemonchus placei and Trichostrongylus axei. The mixed infection by several species from the genera is the cause of parasitic gastroenteritis in cattle in Zimbabwe. Production and husbandry practices, season, host age and environment are considered to be the main factors that influence gastrointestinal nematode infection in cattle. The geographical distribution of the gastrointestinal nematodes is also reviewed in relation to the climatic conditions of the country. Various control options are discussed and how they are applicable to the Zimbabwean situation. Based on reports and existing data on the epidemiological features of the gastrointestinal nematode infection in cattle, practical control measures are critically reviewed and recommendations are made for a national control programme.

Conservation of indigenous cattle genetic resources in Southern Africa's smallholder areas: turning threats into opportunities - A review

The current review focuses on characterization and conservation efforts vital for the development of breeding programmes for indigenous beef cattle genetic resources in Southern Africa. Indigenous African cattle breeds were identified and characterized using information from refereed journals, conference papers and research reports. Results of this current review reviewed that smallholder beef cattle production in Southern Africa is extensive and dominated by indigenous beef cattle strains adaptable to the local environment. The breeds include Nguni, Mashona, Tuli, Malawi Zebu, Bovino de Tete, Angoni, Landim, Barotse, Twsana and Ankole. These breeds have important functions ranging from provision of food and income to socio-economic, cultural and ecological roles. They also have adaptive traits ranging from drought tolerant, resistance to ticks and tick borne diseases, heat tolerance and resistance to trypanosomosis. Stakeholders in the conservation of beef cattle were also identified and they included farmers, national government, research institutes and universities as well as breeding companies and societies in Southern Africa. Research efforts made to evaluate threats and opportunities of indigenous beef cattle production systems, assess the contribution of indigenous cattle to household food security and income, genetically and phenotypically characterize and conserve indigenous breeds, and develop breeding programs for smallholder beef production are highlighted. Although smallholder beef cattle production in the smallholder farming systems contributes substantially to household food security and income, their productivity is hindered by several constraints that include high prevalence of diseases and parasites, limited feed availability and poor marketing. The majority of the African cattle populations remain largely uncharacterized although most of the indigenous cattle breeds have been identified.

Prevalence of Cryptosporidia, Eimeria, Giardia, and Strongyloides in pre-weaned calves on smallholder dairy farms in Mukurwe-ini district, Kenya

AIM

Gastrointestinal diseases are among the leading causes of calf morbidity and mortality in Kenya and elsewhere. This study was undertaken to determine the prevalence of Cryptosporidia, Eimeria, Giardia, and Strongyloides in calves on smallholder dairy farms (SDF) in Mukurwe-ini District, Nyeri County, Kenya. These infections have been associated with economic losses by decreased growth rates, decreased productivity, and increased susceptibility to other diseases.

MATERIALS AND METHODS

An observational study was conducted on 109 farms in Mukurwe-ini District, Nyeri County, Kenya, where 220 calf fecal samples (each calf at 4 and 6 weeks of age) from 110 calves (1 set of twins) were collected and analyzed for Cryptosporidia, Eimeria, Giardia, and helminth parasites.

RESULTS

Eimeria oocysts, Cryptosporidia oocysts, and Strongyloides eggs were detected in the fecal samples examined, but no Giardia cysts were found. The overall period prevalence of Eimeria, Cryptosporidia, and Strongyloides was 42.7% (47/110), 13.6% (15/110), and 5.4% (6/110), respectively. The prevalence at 4 weeks of age for Eimeria, Cryptosporidia, and Strongyloides was 30.0% (33/110), 8.2% (9/110), and 3.7% (4/109), respectively, while the prevalence at 6 weeks of age was 20.2% (22/109), 6.5% (7/107), and 2.7% (3/110), respectively. There was, however, no significant difference in the prevalence at 4 and 6 weeks (p>0.05).

CONCLUSION

Findings from this study show that Eimeria, Cryptosporidia, and Strongyloides, are prevalent in the study area and indicate the need to adopt optimal management practices to control infections in calves.

The effect of gastrointestinal nematode infection level on grazing distance from dung

Avoiding grazing near feces is an efficient strategy to prevent parasitic infection and contamination; therefore, in the evolution of herbivorous species, this behavior may have developed as a mechanism to protect the host against infection by gastrointestinal nematodes. The aim of this study was to assess whether grazing distance from dung is related to the level of parasitic infection in cattle. Based on Fecal Egg Count (FEC) means, 18 castrated male steers, aged 18 months, were divided into three groups: High (FEC ≥ 315); Medium (FEC = 130–160); and Low (FEC = 40–70). To analyze the response to a new natural infection by gastrointestinal nematodes and to standardize infection levels, all animals received anthelmintic treatment at twenty days prior to field observation. Three observers simultaneously collected data on grazing behavior for 2.5 hours/week for 12 weeks. Observers recorded the distance when grazing occurred at less than one meter from dung. Every two weeks, fecal samples were collected for FEC, as well as serum samples to measure immunoglobulin G (IgG) levels against larvae and adult antigens of the parasitic species Haemonchus placei. All groups grazed farther from the dung on days of greater insolation (r = 0.62; P = 0.03). Animals with high levels of parasitism grazed farther from the dung (P < 0.05) but had lower levels (P < 0.0001) of IgG serum levels compared to those with medium and low levels of infection. FEC values varied over the experiment, remaining below 200 for the low and medium group and reaching 1000 (P < 0.01) for the animals with the highest rates of parasitism. Our results indicate that cattle showing high levels of parasitism are more likely to avoid contaminated areas than animals with lower infection levels, and the immune system seems to be involved in such behavior.

Splice variants and regulatory networks associated with host resistance to the intestinal worm Cooperia oncophora in cattle

To elucidate the molecular mechanism of host resistance, we characterized the jejunal transcriptome of Angus cattle selected for parasite resistance for over 20 years in response to infection caused by the intestinal worm Cooperia oncophora. The transcript abundance of 56 genes, such as that of mucin 12 (MUC12) and intestinal alkaline phosphatase (ALPI), was significantly higher in resistant cattle. Novel splicing variants, exon skipping events, and gene fusion events, were also detected. An algorithm for the reconstruction of accurate cellular networks (ARACNE) was used to infer de novo regulatory molecular networks in the interactome between the parasite and host. Under a combined cutoff of an error tolerance (ϵ = 0.10) and a stringent P-value threshold of mutual information (1.0 × 10(-5)), a total of 229,100 direct interactions controlled by 20,288 hub genes were identified. Among these hub genes, 7651 genes had ≥ 100 direct neighbors while the top 9778 hub genes controlled more than 50% of total direct interactions. Three lysozyme genes (LYZ1, LYZ2, and LYZ3), which are co-located in bovine chromosome 5 in tandem and are strongly upregulated in resistant cattle, shared a common regulatory network of 55 genes. These ancient antimicrobials were likely involved in regulating host-parasite interactions by affecting host gut microbiome. Notably, ALPI, known as a gut mucosal defense factor, controlled a molecular network consisting 410 genes, including 14 transcription factors (TF) and 10 genes that were significantly regulated in resistant cattle. Several large regulatory networks were controlled by TF, such as STAT6, SREBF1, and ELF4. Gene ontology (GO) processes significantly enriched in the regulatory network controlled by STAT6 included lipid metabolism. Our findings provide insights into the immune regulation of host-parasite interactions and the molecular mechanisms of host resistance in cattle.

Nematode-coccidia parasite co-infections in African buffalo: Epidemiology and associations with host condition and pregnancy

Co-infections are common in natural populations and interactions among co-infecting parasites can significantly alter the transmission and host fitness costs of infection. Because both exposure and susceptibility vary over time, predicting the consequences of parasite interactions on host fitness and disease dynamics may require detailed information on their effects across different environmental (season) and host demographic (age, sex) conditions. This study examines five years of seasonal health and co-infection patterns in African buffalo (Syncerus caffer). We use data on two groups of gastrointestinal parasites, coccidia and nematodes, to test the hypothesis that co-infection and season interact to influence (1) parasite prevalence and intensity and (2) three proxies for host fitness: host pregnancy, host body condition, and parasite aggregation. Our results suggest that season-dependent interactions between nematodes and coccidia affect the distribution of infections. Coccidia prevalence, coccidia intensity and nematode prevalence were sensitive to factors that influence host immunity and exposure (age, sex, and season) but nematode intensity was most strongly predicted by co-infection with coccidia and its interaction with season. The influence of co-infection on host body condition and parasite aggregation occurred in season-dependent manner. Co-infected buffalo in the early wet season were in worse condition, had a less aggregated distribution of nematode parasites, and lower nematode infection intensity than buffalo infected with nematodes alone. We did not detect an effect of infection or co-infection on host pregnancy. These results suggest that demographic and seasonal variation may mediate the effects of parasites, and their interactions, on the distribution and fitness costs of infection.

Endoparasitismo gastrintestinal em cabras da raça Anglonubiana

A dificuldade de manutenção do rebanho em condições sanitárias adequada compromete a eficiência da criação de caprinos, principalmente em relação ao controle de endoparasitas. O objetivo com este trabalho foi avaliar a sensibilidade de matrizes da raça Anglonubiana a nematoides gastrintestinais, considerando as cabras estratificadas por estágio fisiológico (lactantes e não lactantes) dentro de três classes de idade. Utilizou-se as características: Ovos por grama de fezes (OPG), Grau de anemia (indicado pelo método Famacha©), Peso e Escore da condição corporal e porcentagem de coletas de fezes cujo valor do OPG foi igual a Zero, variável utilizada para demonstrar a resposta ao antihelmintico, disponibilizadas pelo banco de dados dessa raça na UFPI. Os dados são referentes ao período de janeiro de 2009 a dezembro de 2011. As cabras em lactação apresentaram maior valor médio de OPG, maior grau de anemia, menor escore corporal e menor quantidade de coleta de fezes com valor de OPG zero, que as cabras não lactantes, independentemente da classe de idade considerada. Assim, a lactação aumenta a sensibilidade a endoparasitismo em matrizes da raça Anglonubiana. A elevação do OPG tende a se mostrar associada ao maior grau de anemia determinado pelo método Famacha©, que levam a redução da condição corporal.

Analysis of the mucosal immune responses induced by single and trickle infections with the bovine abomasal nematode Ostertagia ostertagi

The purpose of this study was to provide more information on the kinetics of the immunological changes occurring in the abomasal mucosa after single and trickle infections with the bovine parasite Ostertagia ostertagi. The time course analysis of gene expression revealed that the major changes coincided with the emergence of adult worms from the gastric glands. These changes consisted of a simultaneous upregulation of Th1- and Th2-type cytokines. In addition, a single O. ostertagi infection elicited an upregulation of the epithelial-derived cytokine IL33, while TSLP expression levels were not impacted. Apart from the massive increase in inflammatory cytokines IL6, IL17 and IL21, O. ostertagi infection also elicited an upregulation of the immunosuppressors TGFB, IL10 and ARG1, as well as NK and γδ-T cell markers. Furthermore, the cytotoxic factors granulysin, perforin and granzyme B were upregulated following an O. ostertagi infection. Analysis of cytokine transcript levels in animals receiving trickle infections for 60 days showed a similar trend as observed following a single infection except for IL33, IL6, GATA-3, TBX21 and NCR1, which were no longer upregulated after trickle infections. Finally, the long trickle infections were associated with mucosal eosinophilia and mastocytosis.

A genome-wide survey reveals a deletion polymorphism associated with resistance to gastrointestinal nematodes in Angus cattle

Gastrointestinal (GI) nematode infections are a worldwide threat to human health and animal production. In this study, we performed a genome-wide association study between copy number variations (CNVs) and resistance to GI nematodes in an Angus cattle population. Using a linear regression analysis, we identified one deletion CNV which reaches genome-wide significance after Bonferroni correction. With multiple mapped human olfactory receptor genes but no annotated bovine genes in the region, this significantly associated CNV displays high population frequencies (58.26 %) with a length of 104.8 kb on chr7. We further investigated the linkage disequilibrium (LD) relationships between this CNV and its nearby single nucleotide polymorphisms (SNPs) and genes. The underlining haplotype blocks contain immune-related genes such as ZNF496 and NLRP3. As this CNV co-segregates with linked SNPs and associated genes, we suspect that it could contribute to the detected variations in gene expression and thus differences in host parasite resistance.