Shifts in the Fecal Microbial Community of Cystoisospora suis Infected Piglets in Response to Toltrazuril

Comparison of an injectable toltrazuril-gleptoferron and an oral toltrazuril + injectable gleptoferron in piglets: Hematinic activities and pharmacokinetics

Iron deficiency anemia (IDA) and cystoisosporosis are the most common clinical conditions of fast-growing piglets. Until now, IDA and cystoisosporosis have been managed by intramuscular injection of iron complexes (such as dextran or gleptoferron) and oral administration of toltrazuril. Recently, a new combination product containing toltrazuril and gleptoferron for intramuscular application (Forceris®) has been registered. The objective of this study was to compare the pharmacokinetic profiles of toltrazuril and its main metabolite, toltrazuril sulfone, following a single oral (Baycox®) or intramuscular (Forceris®, a toltrazuril-iron combination product) administration at 20 mg/kg to young suckling piglets. The orally treated piglets were also supplemented with iron (Gleptosil®), and the hematinic activities were compared. Piglets in both groups received comparable doses. The peak concentration (Cmax) of toltrazuril after intramuscular administration was 11% lower than that after oral administration (p = .376). However, the exposure to toltrazuril (AUC) was significantly increased (40% higher) when toltrazuril was administered intramuscularly (p = .036). The Cmax and AUC values of the active metabolite, toltrazuril sulfone were 39% and 34% higher, respectively, after intramuscular administration (p = .007 and 0.008, respectively). Piglets in both groups were properly protected against IDA. In conclusion, a higher relative bioavailability of toltrazuril is observed when toltrazuril is administered intramuscularly.

The effect of an injectable toltrazuril - gleptoferron (Forceris®) on Cystoisospora suis oocyst excretion and growth of neonatal piglets pre- and post-weaning

In this study the efficacy of an intramuscular formulation of toltrazuril combined with gleptoferron for the control of porcine cystoisosporosis caused by Cystoisospora suis was investigated. The study was carried out on three Belgian farms with a confirmed history of C. suis infections. As none of the farms implemented a standardized toltrazuril treatment regimen for their piglets, the presence of resistant C. suis strains seems improbable. In total 90 litters, representing 1249 piglets, were included in the study and randomly allocated to either the treatment or control group. Piglets in the treatment group received a single intramuscular injection, containing 45 mg toltrazuril and 200 mg gleptoferron, between 1 and 3 days of age. Piglets in the control group received a single injection with only 200 mg gleptoferron. The effect of treatment on oocyst excretion, expressed in oocysts per gram of feces (OPG), average daily weight gain (ADG) and mortality was determined both pre- and post-weaning. A significant decrease in OPG as well as a decrease in the number of litters (pre-weaning) and pens (post-weaning) that tested positive for cystoisosporosis, was observed in the treated animals compared to the controls. Furthermore, treatment resulted in an increased ADG during the period from day 1 to day 21 (p-value: 0.03881). There was no significant difference in mortality observed between the treatment group to the control group (p-value: 0.2167). To our knowledge, this is the first report on the effect of toltrazuril on oocyst excretion after weaning. This finding highlights the potential long-term benefits of the treatment beyond the initial administration.

Cystoisospora suis in Portugal: an observational study of prevalence, management, and risk factors

BACKGROUND

Neonatal coccidiosis is a common and important disease of suckling piglets in modern farming caused by Cystoisospora suis. Prevalence rates are high, namely, in Portugal, although no recent data are available. The metaphylactic administration of a single dose of toltrazuril and hygienic measures are the backbone of control strategies on positive farms. However, several studies have shown that these programs are not always effective, underlining the need to revise the risk factors and control strategies currently applied. The present study evaluated C. suis prevalence on Portuguese farms and assessed the risk factors associated with facilities and farm rearing practices.

RESULTS

From the 27 tested farms, 23 were positive to Cystoisopora suis (85.2%). In total, 258 litters were sampled (accounting for 516 samples-2 samples per litter), with an average of 59.7% of positive litters per positive farm. Faecal pools from litters, in which liquid faeces predominated had a higher probability of containing oocysts than litter pools with mainly solid (Odds Ratio: 9.87; p < 0.0001) or pasty faeces (OR: 7.05; p = 0.001), and samples obtained from younger animals had higher oocyst counts (coefficient: - 0.0720; 95% CI - 0.125; - 0.019). No significant effect of toltrazuril administration was observed on the positivity rate, and none of the tested farms used disinfectants with official claims against parasites and known anticoccidial effects (e.g., cresol-based products).

CONCLUSIONS

The C. suis prevalence on Portuguese swine farms appears to be similar to the prevalence found in other European countries. Repeated sampling of the same litter and the use of autofluorescence microscopy after a modified Ritchie technique seems to have increased sensitivity and consequently the detection rate of positive litters. Finally, despite the common use of oral toltrazuril, C. suis control programs appear to not always be effective (based on the detection of oocysts in faecal samples), suggesting the need to revise the control strategies applied in the field, including management factors and choices of disinfectant products.

Temporal Microbial Dynamics in Feces Discriminate by Nutrition, Fecal Color, Consistency and Sample Type in Suckling and Newly Weaned Piglets

Feces enable frequent samplings for the same animal, which is valuable in studies investigating the development of the gut microbiome in piglets. Creep feed should prepare the piglet's gut for the postweaning period and shape the microbiome accordingly. Little is known about the variation that is caused by differences in fecal color and consistency and different sample types (feces versus swab samples). Therefore, this study evaluated the age-related alterations in the microbiome composition (16S rRNA gene) in feces of suckling and newly weaned piglets in the context of nutrition and fecal consistency, color and sample type from day 2 to 34 of life. Feces from 40 healthy piglets (2 each from 20 litters) were collected on days 2, 6, 13, 20, 27, 30 and 34. Weaning occurred on day 28. Half of the litters only drank sow milk during the suckling phase, whereas the other half had access to creep feed from day 10. Creep feeding during the suckling phase influenced the age-related total bacterial and archaeal abundances but had less of an influence on the relative bacterial composition. Results further showed different taxonomic compositions in feces of different consistency, color and sample type, emphasizing the need to consider these characteristics in comprehensive microbiome studies.

Microbiome-Metabolomics Analysis of the Impacts of Cryptosporidium muris Infection in BALB/C Mice

Cryptosporidium is a leading cause of diarrheal disease and mortality in young children worldwide. Cryptosporidium invades small intestinal epithelial cells and forms a unique intracellular niche, a process that may alter gut microbes and their production metabolites. However, the mechanism of interactions between gut microbes, metabolites, and parasites is poorly understood. Here, we first characterized the impacts of Cryptosporidium infection on gut microbiota using a microbiome-to-metabolome association study. BALB/c mice were gavaged with Cryptosporidium muris, and fecal samples were collected at 0, 7, 14, 21, and 28 days postinfection (dpi) to observe changes in the intestinal microbes of the body during parasite infection. The infected group had a significantly increased relative abundance of bacterial taxa, such as Lachnospiraceae and Prevotella (P < 0.05), associated with the biosynthesis of short-chain fatty acids (SCFAs). Metabolites related to the metabolic pathways, steroid hormone biosynthesis, and biosynthesis of unsaturated fatty acids pathway were upregulated at 7 dpi, indicating that related metabolites in the biosynthesis of unsaturated fatty acids may be essential for C. muris reproduction in vivo. The metabolites involved in metabolic pathways, bile secretion, and primary bile acid biosynthesis were upregulated at 14 dpi, and we speculate that these metabolites may be critical to the growth and development of Cryptosporidium oocysts in the host. Correlation analysis revealed that Firmicutes bacteria are significantly associated with α-linolenic acid metabolism pathways (P< 0.05). The gut microbiota changes dynamically, and the metabolites involved in fatty acid and bile acid biosynthesis may play important roles during cryptosporidiosis. Details of the gut microbiota and the metabolome after infection with Cryptosporidium may aid in the discovery of specific diagnostic markers and help us understand the changes in parasite metabolic pathways. IMPORTANCE Cryptosporidiosis is a gastrointestinal disease in humans and animals caused by the protozoan parasite Cryptosporidium. Control and treatment of the disease is challenging due to the lack of sensitive diagnostic tools and effective chemotherapy. The dynamics of gut microbiota and metabolites during Cryptosporidium infection may be the key to finding drugs and targets for parasite infection control. Our results indicate that C. muris infection can disrupt gut microbiota and metabolites, resulting in decreased bacterial abundance at the parasitic site. Unsaturated fatty acid pathway biosynthesis-related metabolites are significantly elevated at the patent period. Interestingly, the metabolite pathway that significantly elevated during peak parasite growth was bile acid, the metabolites of which may be important for the circulation of infection of Cryptosporidium oocysts in the host. The enhancing effects of short-chain fatty acid and bile acid metabolism on the growth and development of Cryptosporidium proposed in this study may provide a theoretical basis for future research on novel drugs and vaccines against this intestinal parasite.

Quercetin alleviates intestinal inflammation and improves intestinal functions via modulating gut microbiota composition in LPS-challenged laying hens

Quercetin, a well-known flavonoid, has been demonstrated to exert beneficial effects on intestinal functions and gut microbiota in birds. In this study, we investigated the effects of quercetin supplementation on inflammatory responses, intestinal barrier functions and gut microbial community in LPS-challenged laying hens. A total of two hundred eighty-eight 32-wk-old Jingfen No.6 laying hens were randomly assigned to 3 groups, the CON group, the LC group and the LQ group. LQ group was fed with 0.4 mg/kg quercetin and at the end of 12 wk, LC and LQ groups were challenged intraperitoneally with lipopolysaccharide (LPS). After LPS challenge, 8 birds of each group were randomly selected and sampled. LPS challenge induced an obvious intestinal mucosal injury, necrosis and shedding, while quercetin intervention maintained its structure. Quercetin significantly decreased the elevated malondialdehyde contents (P < 0.05), and increased the activity of total antioxidant capacity and glutathione peroxidase (P < 0.05) in intestinal mucosa of LPS-challenged laying hens. Quercetin rescued the LPS-induced decreases in goblet cell density and mucin2 expression levels (P < 0.05). There was a significant decline (P < 0.05) in the mRNA expression of Claudin1 and Occludin in intestinal mucosa of LPS-challenged layers, which could be alleviated (P < 0.05) by dietary quercetin. LPS challenge induced the increased expression levels (P < 0.05) of IL-1β and TLR-4 in intestinal mucosa, while these rises could be reversed (P < 0.05) following dietary quercetin supplementation. LPS challenge induced a shift in gut microenvironment, and quercetin addition could elevate the relative abundance of some short chain fatty acids (SCFA)-producing or health-promoting bacteria such as Phascolarctobacterium, Negativicutes, Selenomonadales, Megamonas, Prevotellaceae, and Bacteroides_salanitronis. In conclusion, dietary quercetin addition ameliorated the LPS challenge-induced intestinal inflammation and improved intestinal functions, possibly associated with its modulation on gut microbiota, particularly the increased population of SCFA-producing bacteria.

Short-Chain Fatty Acids Modulate Permeability, Motility and Gene Expression in the Porcine Fetal Jejunum Ex Vivo

Postnatally, short-chain fatty acids (SCFA) are important energetic and signaling agents, being involved in host nutrition, gut imprinting and immune and barrier function. Whether SCFA exert similar effects during the late fetal phase has been insufficiently elucidated. This study aimed to evaluate whether the fetal jejunum senses SCFA and whether SCFA modify the muscle tension and epithelial permeability and related signaling in jejunal tissue from the porcine fetus in late gestation. Exposure of fetal jejunal tissue to a mix of SCFA (70 µmol/mL) in an organ bath for 20 min lowered the muscle tension. Moreover, SCFA decreased the transepithelial conductance while increasing the short-circuit current in the Ussing chamber, indicating reduced permeability and increased SCFA absorption. Gene expression in the tissues harvested from the Ussing chamber after 30 min indicated downregulation of the expression of receptors (i.e., FFAR2 and TLR2), MCT1 and tight-junction and adherens proteins, which may be a negative feedback response to the applied high SCFA concentration compared with the micromolar concentration detected in fetal gastric fluid. Taken together, our data demonstrate that the fetal jejunum senses SCFA, which trigger electrophysiological, muscle contraction and related gene transcription responses. Hence, SCFA may play a role in prenatal gut nutrition and imprinting.

The transcriptome from asexual to sexual in vitro development of Cystoisospora suis (Apicomplexa: Coccidia)

The apicomplexan parasite Cystoisospora suis is an enteropathogen of suckling piglets with woldwide distribution. As with all coccidian parasites, its lifecycle is characterized by asexual multiplication followed by sexual development with two morphologically distinct cell types that presumably fuse to form a zygote from which the oocyst arises. However, knowledge of the sexual development of C. suis is still limited. To complement previous in vitro studies, we analysed transcriptional profiles at three different time points of development (corresponding to asexual, immature and mature sexual stages) in vitro via RNASeq. Overall, transcription of genes encoding proteins with important roles in gametes biology, oocyst wall biosynthesis, DNA replication and axonema formation as well as proteins with important roles in merozoite biology was identified. A homologue of an oocyst wall tyrosine rich protein of Toxoplasma gondii was expressed in macrogametes and oocysts of C. suis. We evaluated inhibition of sexual development in a host-free culture for C. suis by antiserum specific to this protein to evaluate whether it could be exploited as a candidate for control strategies against C. suis. Based on these data, targets can be defined for future strategies to interrupt parasite transmission during sexual development.

Absorption and Distribution of Toltrazuril and Toltrazuril Sulfone in Plasma, Intestinal Tissues and Content of Piglets after Oral or Intramuscular Administration

Piglet coccidiosis due to Cystoisospora suis is a major cause of diarrhea and poor growth worldwide. It can effectively be controlled by application of toltrazuril (TZ), and oral formulations have been licensed for many years. Recently, the first parenteral formulation containing TZ in combination with iron (gleptoferron) was registered in the EU for the prevention of coccidiosis and iron deficiency anemia, conditions in suckling piglets requiring routine preventive measures. This study evaluated the absorption and distribution of TZ and its main metabolite, toltrazuril sulfone (TZ-SO₂), in blood and intestinal tissues after single oral (20 mg/kg) or single intramuscular (45 mg/piglet) application of TZ. Fifty-six piglets were randomly allocated to the two treatment groups. Animals were sacrificed 1-, 5-, 13-, and 24-days post-treatment and TZ and TZ-SO₂ levels were determined in blood, jejunal tissue, ileal tissue, and mixed jejunal and ileal content (IC) by high performance liquid chromatography (HPLC). Intramuscular application resulted in significantly higher and more sustained concentrations of both compounds in plasma, intestinal tissue, and IC. Higher concentrations after oral dosing were only observed one day after application of TZ in jejunum and IC. Toltrazuril was quickly metabolized to TZ-SO₂ with maximum concentrations on day 13 for both applications. Remarkably, TZ and TZ-SO₂ accumulated in the jejunum, the primary predilection site of C. suis, independently of the administration route, which is key to their antiparasitic effect.

Pilot Sub-Study of the Effect of Hepatitis C Cure by Glecaprevir/Pibrentasvir on the Gut Microbiome of Patients with Chronic Hepatitis C Genotypes 1 to 6 in the Mythen Study

In this small pilot sub-study, longitudinal gut microbiota composition changes, after successful treatment of hepatitis C virus (HCV) with the co-formulated glecaprevir/pibrentasvir (GLE/PIB), were analyzed before treatment (baseline) and 12 weeks post-treatment. Participating patients provided a fresh stool sample the week before their study visit, from which microbial DNA was extracted and sequenced for the 16S rRNA region in an Illumina MiSeq2 platform. Microbial and statistical analyses were conducted to determine the alpha-diversity (number of different taxa within a sample) and beta-diversity (number of overlapping taxa between samples). Stool samples from 58 patients were eligible for analysis. There were 27 patients with HCV genotype 1, 10 with genotype 2, 16 with genotype 3, and 5 with genotype 4. No statistically significant differences in gut microbiota diversity, species richness, or microbial community pattern were found at baseline and at post-treatment Week 12. Lack of statistically significant differences remained consistent in further analysis by demographic and baseline disease characteristics. Surprisingly, no statistically significant changes in alpha- and beta-diversity were seen in the microbiota after GLE/PIB treatment, though there was a trend toward less richness over time. Further investigation is needed into this unexpected outcome to better understand the role of HCV treatment and the gut microbiota.