Molecular diagnosis of Eimeria stiedae in hepatic tissue of experimentally infected rabbits

Camellia sinensis Aqueous Extract: A Promising Candidate for Hepatic Eimeriosis Treatment in Rabbits

Eimeria stiedae (E. stiedae) is a common coccidian species that infects the liver and causes economic losses for the rabbit industry. This study aimed to determine the efficiency of green tea aqueous extract (GTE) as a natural treatment for eimeriosis caused by E. stiedae. Male rabbits Cuniculus L. (Oryctolagus) of the New Zealand White rabbit strain (4-4.5 months) were used, as they are suitable for research and conducting experiments. Thirty rabbits were allocated into six groups, with five rabbits in each group; the G1 group (non-infected untreated) served as a negative control group; the G2 group was not infected and treated with 250 mg GTE; the G3 group was not infected and treated with 500 mg GTE; the G4 group was untreated and was infected with 3 × 104 Sporulated E. stiedae oocysts, which served as a positive control group; the G5 group was infected and treated with 250 mg GTE; and the G6 group was infected and treated with 500 mg GTE. The hematological and biochemical analyses of each group of rabbit sera were carried out. Phytochemical analysis was performed to evaluate the active components in GTE leaves using the following methods: IR spectroscopy, liquid chromatography-mass spectrometry (LC-MS), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy. The infected rabbit groups treated with GTE at both doses of 250 and 500 mg/kg exhibited a significant decrease in the extent of E. stiedae oocyst shedding compared with the infected untreated group at 14, 21, and 28 days post-infection. Also, treatment with green tea showed improvement in liver weight compared with the enlarged livers of infected, untreated rabbits. The disturbance in serum liver enzymes' gamma-glutamyl transferase (GGT) and aspartate aminotransferase (AST/GOT) levels, as well as serum glucose, potassium, uric acid, cholesterol, and urea levels, were improved after the treatment of infected rabbit groups with green tea compared with the infected untreated group. Moreover, in this study, the images of the egg stages of the parasite were taken using a fluorescence microscope at 25 µm and 26 µm magnifications. This study provides promising results for the effective cell absorption of the aqueous extract of green tea, which was confirmed in the analyzed images using a scanning electron microscope at 5 µm and 20 µm magnifications.

Attenuation of pathogenesis of Eimeria stiedae sporulated oocysts using Egyptian alginate propolis nanoparticles

BACKGROUND

Coccidiosis is a costly and widespread infectious disease that affects mammals and causes huge losses for the global rabbit meat industry. This study evaluated the potency of Egyptian alginate propolis nanoparticles (NPs) in attenuating the infectivity of Eimeria stiedae sporulated oocysts. The gelification method was used to prepare alginate propolis NPs, which were then characterized using a transmission electron microscope and zeta potential analysis.

RESULTS

The results revealed that the zeta potential of the prepared alginate propolis NPs increased from - 60.60 ± 9.10 mV to -72.26 ± 6.04 mV. The sporulated oocysts were treated with 50 mg/mL of the alginate propolis NPs. Thereafter, the treated oocysts were tested for their ability to infect rabbits. The rabbits were divided into three groups: the healthy control (G1) group, the infected control (G2) group, and the treated oocyst-infected (G3) group. The rabbits were sacrificed 43 days post-infection (dpi). The infectivity of the oocysts was assessed. The treated oocyst-infected rabbits exhibited slight abdominal distension and dullness symptoms. The G3 group had no oocyst output, with a 100% reduction from 41 dpi until the end of the experiment. Immunologically, the IgG level of the G2 group gradually increased (p ≤ 0.05) much more than that of the G3 group. The IL-12 level in the G3 group significantly increased from 16 dpi until the end of the experiment, nearly reaching the level in healthy animals. Decreased CD4+ and CD8+ immunolabelling was observed in the liver sections of the group infected with the alginate propolis NP-treated oocysts, and there was a remarkable improvement in the histopathological parameters.

CONCLUSIONS

These data indicate that Alg propolis NPs are sufficient to reduce the infectivity of E. stiedae oocysts.

Occurrence, Histopathological Findings, and Molecular Identification of Pathogenic Eimeria Infections in Rabbits (Mammalia: Lagomorpha) in Japan

PURPOSE

Eimeria spp. are commonly found among rabbits (Mammalia: Lagomorpha) worldwide. Among the 11 Eimeria species, several are highly virulent, including E. intestinalis and E. flavescens, which cause intestinal coccidiosis, and E. stiedae, which causes hepatic coccidiosis. Unlike other countries, the occurrence of Eimeria infections in rabbits in Japan remains unknown, except for one reported case of natural infection.

METHODS

We surveyed Eimeria infections in clinically affected rabbits over the past approximately 10 years at Livestock Hygiene Centers in 42 prefectures. A total of 16 tissue samples (14 liver, 1 ileum, and 1 cecum) were collected from 15 rabbits in 6 prefectures.

RESULTS

Characteristic histopathologic findings were observed, especially around the bile ducts, depending on the developmental stages of the parasites. Eimeria stiedae and E. flavescens were successfully identified by PCR and sequencing analyses in 5 liver samples and 1 cecum sample, respectively.

CONCLUSION

Our results could enhance understanding of infection with Eimeria spp. in rabbits in Japan and contribute to pathological or molecular diagnoses.

Hepatic Coccidiosis in Wild Rabbits in Greece: Parasite Detection on Liver Imprints and the Associated Biochemical Profile

(1) Background: Rabbit hepatic coccidiosis, caused by Eimeria stiedae, is a devastating disease with high morbidity and mortality rates. The disease is well described in rabbits, but little is known about E. stiedae infection in wild rabbits. In this study, we investigated the presence of E. stiedae infection in wild rabbits from the island of Lemnos, Greece, where this species is overpopulated, and the effects of infection on common hepatic biomarkers. (2) Methods: We used liver impression smears to detect the coccidian oocysts, and we defined the liver biochemical profile of the infected individuals. (3) Results: Overall, 13.3% of the liver imprints examined were positive for the presence of coccidial oocysts. The activities of liver enzymes, that is, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and glutamyltransferase (GGT), as well as globulins (GLOB), were increased while the concentrations of albumins (ALB), total proteins (TP) and the albumin to globulin (A/G) ratio were decreased in the infected individuals compared to the non-infected ones. (4) Conclusions: This study adds to the current knowledge on the pathogens affecting wild rabbits and those circulating in this population on the island of Lemnos, Greece. Moreover, we showed that E. stiedae infection exerts pathological effects on the hepatocyte integrity and liver function of wild rabbits, as reflected by the abnormal values of liver injury and dysfunction biomarkers.

Protective Effect of Litchi chinensis Peel Extract-Prepared Nanoparticles on Rabbits Experimentally Infected with Eimeria stiedae

The present study used Litchi chinensis peel extract to synthesize silver nanoparticles (AgNPs). This technique is eco-friendly and can be performed in a single step; thus, it has attracted great attention for NPs biosynthesis. Herein, we biosynthesized AgNPs with L. chinensis peel extract and examined their anticoccidial activity in rabbit hepatic coccidiosis induced by E. stiedae infection. Thirty-five rabbits were allocated into seven groups: a healthy group (G1), an infected control group (G2), four groups infected before treatment with 10 mg/kg L. chinensis peel extract-biosynthesized AgNPs (G3, G5) or 50 mg/kg amprolium (G4, G6), and rabbits infected after two weeks of pretreatment with 10 mg/kg L. chinensis eel extract-biosynthesized AgNPs (G7). In this study, both pre-and post-treatment with AgNPs produced a substantial reduction in fecal oocyst output, liver enzyme levels, and histopathological hepatic lesions relative to the infected group. In conclusion, L. chinensis peel extract-prepared AgNPs should be considered harmless and efficient in the cure of hepatic coccidiosis in rabbits.

Molecular identification of Eimeria species in liver and feces of naturally infected rabbits in Japan

Among the 11 species of Eimeria in rabbits, some of which are known to be pathogenic and cause enteritis, E. stiedae induces severe liver lesions resulting in elevated mortality. Unlike in other countries, the incidence and prevalence of the parasites in rabbits have not been reported in Japan. In the present study, we histopathologically analyzed hepatic coccidiosis in a rabbit and attempted several primers to genetically identify the parasites and investigated the prevalence of Eimeria species at the same farm. In the liver of the affected rabbit, we observed fibrosis and edema around multiple bile ducts and epithelial cell hyperplasia of the bile ducts. Large numbers of developing parasites of Eimeria spp., mainly oocysts, were present in the bile ducts. PCR and sequencing analyses with the published primers for Cyclospora and Eimeria spp. were used to successfully identify the parasites in the liver as E. stiedae. The oocysts of Eimeria spp. were detected in 13 out of 20 fecal samples collected from other rabbits at the farm, and five Eimeria spp. (E. perforans, E. flavescens, E. exigua, E. magna, and E. vejdovskyi) were genetically confirmed. Our results provide the first indication that Eimeria spp., including highly pathogenic species, are present in Japan and the primer set used herein can be a useful tool for the identification of rabbit Eimeria spp.

Biochemical and Pathomorphological Investigations on Rabbits with Experimentally Induced Hepatic Eimeriosis

The present study aimed to evaluate the changes in concentrations of some biochemical parameters, as well as macro and microscopic alterations during Eimeria stiedae infection in rabbits. The experiment was performed using 12 three-month-old healthy rabbits, randomly allocated into 2 equal groups: G1 (controls, uninfected animals) and G2 (rabbits infected with E. stiedae). Blood samples were collected at time zero (prior to the infection), 6th, 24th, and 48th hours, and also 7th, 14th, 21st, 28th days after the infection. After sampling, the blood was centrifuged, plasma was separated and frozen at −20 ºC until analyzed. Thawed plasma was used for the quantitative determination of haptoglobin (Hp), total protein (TP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), total cholesterol (TC), total bilirubin (TBIL), urea, and creatinine (CREA). The results in infected rabbits revealed a significant increase in Hp, AST, ALT, GGT, TBIL, and TC levels, as well as a significant decrease in ALP and urea. A weak hyperproteinemia was also observed. There were no changes in CREA concentration. At the end of the clinical investigation, all rabbits were humanely euthanized and necropsied. The post-mortem examination of the infected group revealed hepatomegaly, multifocal yellowish nodules diffusely spread over the liver surface and in the parenchyma, considerably dilated bile ducts, and biliary hyperplasia. Given the results obtained from this experiment, it can be affirmed that hepatic eimeriosis in rabbits is a severe parasitic disease leading to significant disturbances of liver histology and resulting changes in the biochemical profile of infected rabbits.

Global transcriptome landscape of the rabbit protozoan parasite Eimeria stiedae

Background

Coccidiosis caused by Eimeria stiedae is a widespread and economically significant disease of rabbits. The lack of studies on the life-cycle development and host interactions of E. stiedae at the molecular level has hampered our understanding of its pathogenesis.

Methods

In this study, we present a comprehensive transcriptome landscape of E. stiedae to illustrate its dynamic development from unsporulated oocysts to sporulated oocysts, merozoites, and gametocytes, and to identify genes related to parasite-host interactions during parasitism using combined PacBio single-molecule real-time and Illumina RNA sequencing followed by bioinformatics analysis and qRT-PCR validation.

Results

In total, 12,582 non-redundant full-length transcripts were generated with an average length of 1808 bp from the life-cycle stages of E. stiedae. Pairwise comparisons between stages revealed 8775 differentially expressed genes (DEGs) showing highly significant description changes, which compiled a snapshot of the mechanisms underlining asexual and sexual biology of E. stiedae including oocyst sporulation between unsporulated and sporulated oocysts; merozoite replication between sporulated oocysts and merozoites; and gametophyte development and gamete generation between merozoites and gametocytes. Further, 248 DEGs were grouped into nine series clusters and five groups by expression patterns, and showed that parasite–host interaction-related genes predominated in merozoites and gametocytes and were mostly involved in steroid biosynthesis and lipid metabolism and carboxylic acid. Additionally, co-expression analyses identified genes associated with development and host invasion in unsporulated and sporulated oocysts and immune interactions during gametocyte parasitism.

Conclusions

This is the first study, to our knowledge, to use the global transcriptome profiles to decipher molecular changes across the E. stiedae life cycle, and these results not only provide important information for the molecular characterization of E. stiedae, but also offer valuable resources to study other apicomplexan parasites with veterinary and public significance.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04811-5.

Prophylactic and Therapeutic Efficacy of Prebiotic Supplementation against Intestinal Coccidiosis in Rabbits

Simple Summary

There are limitations for using chemical products in meat production. The use of prebiotics to control Eimeria infections in rabbits may be of value. Prebiotics as a prophylaxis resulted in diminishing adverse effects caused by Eimeria spp. through decreasing fecal oocyst counts, retaining body weight, and reducing the number of parasitic stages in the intestinal tissues when compared with the non-supplemented controls.

Abstract

This study was conducted to investigate the effect of prebiotic supplementation against intestinal coccidiosis in rabbits. Fifty male rabbits aged 35–60 days (1–1.5 kg) were divided into prophylactic and therapeutic experiments (five groups, 10 rabbits per group). Prophylactic experiment had prebiotic supplemented (PS-P), non-supplemented infected control (NI-P), and non-supplemented non-infected control (NN-P) groups. Ten days post-prebiotic supplementation (PPS), rabbits in groups PS-P and NI-P were infected orally with 5.0 × 10⁴ sporulated oocysts of mixed Eimeria species. However, therapeutic experiment had prebiotic supplemented (PS-T) and untreated infected (UI-T) groups of naturally infected rabbits with Eimeria species. A significant reduction in oocyst count per gram feces (OPG) (p ≤ 0.05) was reported in the PS-P (57.33 × 10³ ± 2.84) and NI-P (130.83 × 10³ ± 43.38) groups during the experiment. Additionally, rabbits in groups (PS-P, 970.33 ± 31.79 g and NI-P, 870.66 ± 6.66 g) showed weight loss after infection. However, a significant (p ≤ 0.05) decrease in OPG was observed at day seven PPS in the PS-T group (4 × 10³ ± 0.00) when compared with the UI-T group (32 × 10³ ± 7.54). Furthermore, the PS-T group had a higher body weight than rabbits in the UI-T group. Histopathological findings of the intestinal tissues (duodenum, jejunum, and ileum) showed that the counts of the endogenous stages were significantly higher in the NI-P and UI-T groups than in the prebiotic-supplemented groups (PS-P and PS-T). Supplementation of the prebiotic did not have any adverse effects on biochemical parameters, such as AST, ALT, creatinine, total protein, and total cholesterol. In conclusion, prebiotic supplementation can be used to minimize the adverse effects of intestinal coccidiosis in rabbits, which in turn limits body weight loss, especially for the prophylaxis of coccidial infection.

Comparative effects of Herba Cox®, a commercial herbal extract, on rabbits (Oryctolagus cuniculus) experimentally infected with Eimeria stiedae

The objective of this study was to evaluate the efficacy of Herba Cox®, a commercial herbal compound containing extracts from Bombax malabaricum, Aegle marmelos, Anethum foeniculum, Resina salvia, Ferula asafoetida and Papaver somniferum, for the treatment of rabbit hepatic coccidiosis. Thirty rabbits were allocated into three groups (10 × 3), the G1 group served as a negative control group, G2 group (positive control group) was infected with 5 × 10⁴ sporulated E. stiedaeoocysts and served as infected-untreated group, and G3 group was infected with 5 × 10⁴ sporulated E. stiedaeoocysts and treated with Herba Cox®, 1 ml/liter of drinking water, starting 7 days before infection and continuing for 4 weeks post-infection. When compared to the infected group (G2), body weight and weight gain were significantly (P ≤ 0.05) increased, the feed conversion rate was improved and no mortality was detected in infected treated group (G3) and similar to negative control group (G1). In addition, faecal oocyst output and liver enzymes were significantly decreased. Malondialdehyde, nitric oxide, and glutathione concentrations observed in G3 were similar to those in G1. In infected-untreated rabbits (G2), the haemoglobin, lymphocytes, and CD4+/ CD8+ ratio were significantly decreased, while the total leukocyte count, percentage of heterophils, and heterophil/lymphocyte ratio were increased. Significantly more severe histopathological hepatic lesions were observed in G2 when compared to G1 and G3. In conclusion, the obtained results showed that Herba Cox® should be considered a safe and novel effective compound for the treatment of E. stiedae infection in rabbits.