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Dietary probiotics may enhance gut health by directly competing with pathogenic agents and through immunostimulatory effects. These properties are recognized in the context of bacterial and viral pathogens, but less is known about interactions with eukaryotic pathogens such as parasitic worms (helminths). In this study we investigated whether two probiotic mixtures (comprised of Bacillus amyloliquefaciens, B. subtilis , and Enterococcus faecium [BBE], or Lactobacillus rhamnosus LGG and Bifidobacterium animalis subspecies Lactis Bb12 [LB]) could modulate helminth infection kinetics as well as the gut microbiome and intestinal immune responses in pigs infected with the nodular worm Oesophagostomum dentatum . We observed that neither probiotic mixture influenced helminth infection levels. BBE, and to a lesser extent LB, changed the alpha- and beta-diversity indices of the colon and fecal microbiota, notably including an enrichment of fecal Bifidobacterium spp. by BBE. However, these effects were muted by concurrent O. dentatum infection. BBE (but not LB) significantly attenuated the O. dentatum -induced upregulation of genes involved in type-2 inflammation and restored normal lymphocyte ratios in the ileo-caecal lymph nodes that were altered by infection. Moreover, inflammatory cytokine release from blood mononuclear cells and intestinal lymphocytes was diminished by BBE. Collectively, our data suggest that selected probiotic mixtures can play a role in maintaining immune homeostasis during type 2-biased inflammation. In addition, potentially beneficial changes in the microbiome induced by dietary probiotics may be counteracted by helminths, highlighting the complex inter-relationships that potentially exist between probiotic bacteria and intestinal parasites.

The intensity and prevalence of different gastrointestinal nematode species vary across regions worldwide. Oesophagostomum radiatum commonly shows a high occurrence in young cattle. O. radiatum causes anaemia, hypoproteinaemia, and immunopathological changes in the large intestine wall, impairing calves’ body weight gain. This study aimed to assess the impact of natural O. radiatum infection on haematological parameters and immune responses in 23 Nellore calves, considering sex-based differences. Assessments included Oesophagostomum egg count (EPG), worm count, packed cell volume (PCV), total plasma protein, histopathological and immunohistochemistry analyses. A large number of parasites attached to the colon mucosa were observed, along with massive nodule formation and haemorrhagic lesions, mainly within a 20–30 cm-long segment adjacent to the nodules. The maximum mean egg shedding was approximately 165 EPG for males and 173 EPG for female calves; however, males presented a significantly higher worm count (969 ± 200.5) than females (460 ± 99.5). There were significant positive correlations between the total O. radiatum worm count and O. radiatum EPG for both female and male calves. Significant negative correlations were observed between the total O. radiatum worm count and PCV in female calves. Our results demonstrated that natural O. radiatum infection in Nellore calves induced marked immunopathological alterations, including chronic inflammatory responses that impaired intestinal function. Sex-related differences suggested that female calves may develop more effective tissue responses. These findings emphasise the economic impact of subclinical infections and reinforce the importance of control strategies to minimise productivity losses in cattle.

Oesophagostomum bifurcum larvae, cultured from human stools collected in northern Ghana, were used to establish experimental infections in monkeys. A patent infection was established in a rhesus monkey (Macaca mulatta) and this infection was used to generate larvae to inoculate additional monkeys. In all, 17 animals were inoculated. Thirteen of 15 animals developed antibodies to the infection between 19 and 62 days post inoculation (PI); two animals had a positive response before inoculation. Four of ten animals developed patent infections between 88 and 134 days and passed eggs in the faeces. Egg shedding was consistent in only one animal, but at low levels of one or two eggs per 2 mg direct smear, and extended over a 400 day period. In the other three animals, egg shedding was sporadic and of only 2–4 weeks duration. In seven animals necropsied between 19 and 22 days PI, one to 17 early fourth-stage larvae were recovered from nodules in the bowel wall; in an eighth animal examined at 314 days, six immature adult worms (early fifth stage) were recovered from nodules in the bowel wall. The morphological features and growth of these recovered larvae are described. Three animals were inoculated with larvae that had been dried for one week at 28°C; two animals began shedding eggs at 128 and 134 days PI, respectively. The present results suggest that the parasite obtained from humans is poorly adapted to lower primate hosts, and supports the concept that Oesophagostomum bifurcum found in humans and monkeys in the same geographical region of northern Ghana and Togo are distinct and that the infections in humans are not likely to represent zoonotic infections acquired from monkeys.

The in vitro culture of 3rd-stage Oesophagostomum columbianum larvae to the 4th larval stage was achieved in a culture medium of components with a molecular weight less than 6,000. The small mol wt components of chick embryo extract and sheep serum used in the culture medium were prepared by gel filtration. About 60% of the larvae successfully completed the 3rd molt and reached the 4th stage in the simplified medium. Development compared favorably with larvae cultured in vitro in complex media and with in vivo development. Culture medium in which larvae had developed was fractionated by gel filtration and the excluded peak further separated by polyacrylamide disc electrophoresis. The presence of worm antigens was demonstrated. Immunoelectrophoretic studies demonstrated the presence of more precipitating antibodies in mucosal extracts than in sera from hyperinfected sheep.

Extracts of larval and adult Oesophagostomum radiatum failed to protect calves against oral challenge of immunity when the antigens were injected subcutaneously once a week for 3 or 4 weeks. Single intraperitoneal injections of live in-vitro-grown third-stage larvae or a mixture of third-stage, third-molt, and fourth-stage larvae into cattle provided from 44 to 90% and 36 to 83% protection, respectively. The intraperitoneally inoculated larvae penetrated mesenteric tissue and associated lymph nodes producing lesions identical to those in the ileum and cecum of orally inoculated calves. Low-level patent infections developed as a result of the intraperitoneal injections in some of the calves given only third-stage larvae; however, none developed in calves given infections of the mixture of stages.

Exsheathment is crucial in the transition from free-living to parasitic phase for most strongyle nematode species. A greater understanding of this process could help in developing new parasitic control methods. This study aimed to identify commonalities in response to exsheathment triggers (heat acclimation, CO 2 and pH) in a wide range of species ( Haemonchus contortus , Trichostrongylus spp., Cooperia spp., Oesophagostomum spp., Chabertia ovina , and members of the subfamily Ostertagiinae) from sheep, cattle and farmed deer. The initial expectation of similarity in pH requirements amongst species residing within the same organ was not supported, with unexpected pH preferences for exsheathment of Trichostrongylus axei , Trichostrongylus vitrinus , Trichostrongylus colubriformis and Cooperia oncophora. We also found differences between species in their response to temperature acclimation, with higher exsheathment in response to heat shock observed for H. contortus , Ostertagia ostertagi , T. axei , T. vitrinus and Oesophagostomum sikae . Furthermore, some species showed poor exsheathment under all experimental conditions, such as Cooperia curticei and the large intestinal nematodes C. ovina and Oesophagostomum venulosum . Interestingly, there were some significant differences in response depending on the host from which the parasites were derived. The host species significantly impacted on the exsheathment response for H. contortus , Teladorsagia circumcincta, T. vitrinus and T. colubriformis . Overall, the data showed variability between nematode species in their response to these in vitro exsheathment triggers, highlighting the complexity of finding a common set of conditions for all species in order to develop a control method based on triggering the exsheathment process prematurely.

One third of the human population is currently infected by one or more species of parasitic helminths. Certain helminths establish long-term chronic infections resulting in a modulation of the host's immune system with attenuated responsiveness to \"bystander\" antigens such as allergens or vaccines. In this study we investigated whether parasite-derived products suppress the development of allergic inflammation in a mouse model. We show that extract derived from adult male Oesophagostomum dentatum (eMOD) induced Th2 and regulatory responses in BALB/c mice. Stimulation of bone marrow-derived dendritic cells induced production of regulatory cytokines IL-10 and TGF-beta. In a mouse model of birch pollen allergy, co-administration of eMOD with sensitizing allergen Bet v 1 markedly reduced the production of allergen-specific antibodies in serum as well as IgE-dependent basophil degranulation. Furthermore, eMOD prevented the development of airway inflammation, as demonstrated by attenuation of bronchoalveolar lavages eosinophil influx, peribronchial inflammatory infiltrate, and mucus secretion in lungs and IL-4 and IL-5 levels in lung cell cultures. Reduced secretion of Th2-related cytokines by birch pollen-re-stimulated splenocytes and mesenteric lymph node cells was observed in eMOD-treated/sensitized and challenged mice in comparison to sensitized and challenged controls. The suppressive effects of eMOD were heat-stable. Immunization with model antigens in the presence of eMOD reduced production of antibodies to thymus-dependent but not to thymus-independent antigen, suggesting that suppression of the immune responses by eMOD was mediated by interference with antigen presenting cell or T helper cell function but did not directly suppress B cell function. In conclusion, we have shown that eMOD possesses immunomodulatory properties and that heat-stable factors in eMOD are responsible for the dramatic suppression of allergic responses in a mouse model of type I allergy. The identification and characterization of parasite-derived immune-modulating molecules might have potential for designing novel prophylactic/therapeutic strategies for immune-mediated diseases.

Cross antigenicity is the major problem in developing a reliable tool for immunodiagnosis and immunoprophylaxis of parasitic diseases. Mixed infection due to different types of gastrointestinal parasites is more common than single species infection under field condition. The present study was undertaken to detect antigenic cross-reactivity among and of goats by SDS-PAGE and western blot analysis using hyperimmune sera (HIS) rose in rabbit separately against the antigens of the three nematode species. Thirteen, 16 and 14 polypeptides in crude somatic antigen (CSAg) of (CSAg-Hc), (CSAg-Oc) and (CSAg-To), respectively, were resolved in SDS PAGE analyses. It was revealed that 54 kDa peptide was shared by and , whereas 47 kDa peptide was shared by and . Western blot analyses revealed that three immunogenic polypeptides (MW 54, 49 and 42 kDa) in CSAg-Hc, five in CSAg-Oc (54, 47, 44, 38 and 35.5 kDa) and CSAg-To and five polypeptides (90, 51, 47, 39.5 and 31 kDa) in CSAg-To cross-reacted with the heterologous HIS. Four species-specific immunoreactive polypeptides (92, 85, 65 and 39 kDa) of and two (72 & 26 kDa) in were also identified in the study. The shared polypeptides and species-specific polypeptides might be evaluated as protective antigen and subsequently exploitation for developing immunodiagnostic and for immunoprophylactic tools of for these common nematode species.

A cDNA was isolated from an adult male Oesophagostomum dentatum gene library by screening with a male-specific, partial expressed sequence tag (EST) probe identified previously using a differential display technique. The full-length cDNA of 642 bp included 5′ and 3′ untranslated regions of 44 and 121 nucleotides, respectively, and encoded a predicted protein with a putative 18 amino acid signal sequence and a mature polypeptide of 14.7 kDa comprising ∼15% cysteine residues. The amino acid sequence showed similarity with a number of proteins from Caenorhabditis elegans, parasitic nematodes, insects and amphibia, all of which contain a trypsin inhibitor-like cysteine-rich domain. A 3-dimensional structure model constructed for the O. dentatum protein (designated OdmCRP) inferred that it is composed of 2 domains, each with 5 disulfide bonds, which are indicative of the Ascaris family of serine protease inhibitors. These findings indicate that OdmCRP, with 2 structural domains relating to functionally active sites, is a new member of this inhibitor family.