Eimeria bovis: An update on parasite–host cell interactions

High prevalence of pathogenic Eimeria spp. and the main risk factors associated with infection in goats from a semiarid region of Northeastern Brazil

This study aimed to analyze the epidemiology of infections caused by Eimeria spp. in goats bred in an extensive production system in Northeast Brazil. To this end, an epidemiological survey was performed, wherein 350 fecal samples were collected from goats ranging from 3 months to 8 years old across 30 farms. The number of oocysts per gram of feces (OPG) was counted using the Mini-FLOTAC method. Species were identified based on their morphological and morphometric characteristics. Frequencies between animal categories were assessed using the chi-square test and known risk factors after multivariate analysis. Eimeria oocysts were found in 99.4% (346/348) of samples and 100% (30/30) of the farms. The OPG was influenced by the age of the animals; therefore, young goats (up to 6 months old) eliminated more oocysts (2302.6 + 5454.8) than adult goats (881.7 + 1551.5). Three pathogenic species were identified, with two demonstrating a high prevalence: Eimeria arloingi (88.83%) and Eimeria christenseni (44.7%), in addition to Eimeria caprina (3.72%). In the study, the habit of ground feeding and the use of cisterns as water sources were identified as risk factors, with odds ratios of 4.04 and 9.82, respectively. However, cleaning facilities at shorter intervals was a protective factor (OR = 0.19). We concluded that there was a high prevalence of Eimeria infection in goats bred in extensive production systems, even those in semiarid regions. This high prevalence can be attributed to the congregation of animals in shaded areas and the substantial accumulation of fecal matter at night.

Effect of biosynthesized nanoselenium using Azadirachta indica (Meliaceae) leaf extracts against Eimeria papillata infection

Coccidiosis is a protozoan parasitic disease affecting different animal species. Resistance has been reported for all available anticoccidial drugs. Recently, green synthesis of nanoparticles is considered a new therapeutic tool against this parasitic disease. The present work aimed to study the effect of biosynthesized nanoselenium from Azadirachta indica leaf extracts (BNS) against Eimeria papillata-induced infection in mice. The phytochemical analysis of leaf extracts contained 33 phytochemical components. The BNS was spherical with ⁓68.12 nm in diameter and an absorption peak at 308 nm via UV-spectra. The data showed that mice infected with E. papillata revealed the highest oocyst output on the 5th-day post-infection (p.i.). Infection also induced injury and inflammation of the mice jejunum. Treatment with BNS resulted in a 97.21% suppression for the oocyst output. The treated groups with BNS showed enhancement in feed intake as compared to the infected group. Histological examinations showed a significant reduction in the intracellular developmental Eimeria stages in the jejunal tissues of infected-treated mice of about 24.86 ± 2.38 stages/10 villous crypt units. Moreover, there was a significant change in the morphometry for Eimeria stages after the treatment with BNS. Infection induced a disturbance in the level of carbohydrates and protein contents in the infected mice which enhanced after treatment with BNS. In addition, BNS counteracted the E. papillata-induced loss of the total antioxidant capacity. Collectively, BNS is considered a promising anticoccidial and antioxidant effector and could be used for the treatment of coccidiosis.

Gastrointestinal Parasites of Domestic Mammalian Hosts in Southeastern Iran

Gastrointestinal parasites (GIP) are a major cause of disease and production loss in livestock. Some have zoonotic potential, so production animals can be a source of human infections. We describe the prevalence of GIP in domestic mammals in Southeastern Iran. Fresh fecal samples (n = 200) collected from cattle (n = 88), sheep (n = 50), goats (n = 23), camels (n = 30), donkeys (n = 5), horse (n = 1), and dogs (n = 3) were subjected to conventional coprological examination for the detection of protozoan (oo)cysts and helminth ova. Overall, 83% (166/200) of the samples were positive for one or more GIP. Helminths were found in dogs, donkeys, sheep (42%), camels (37%), goats (30%), and cattle (19%), but not in the horse. Protozoa were found in cattle (82%), goats (78%), sheep (60%), and camels (13%), but not in donkeys, dogs, or the horse. Lambs were 3.5 times more likely to be infected by protozoa than sheep (OR = 3.5, 95% CI: 1.05–11.66), whereas sheep were at higher odds of being infected by helminths than lambs (OR = 4.09, 95% CI: 1.06–16.59). This is the first study assessing the prevalence of GIP in domestic mammals in Southeastern Iran.

Prevalence and risk factors of coccidiosis in calves from Veracruz, México

The objectives of the present study were: (1) to determine the prevalence of Eimeria spp. sporulated oocysts in calves from 26 Municipalities in the Central Zone of the State of Veracruz, Mexico, (2) to identify the Eimeria spp. infecting calves, and (3) to identify the risk factors associated with the presence of Eimeria spp. in tropical cattle. A total of 930 individual fecal samples were analyzed by using the McMaster technique; then, oocysts were maintained in 2.5% potassium dichromate to allow sporulation. The general prevalence of calves with Eimeria spp. oocysts was 39.7% (370/930). Of a total of 10 identified species, Eimeria canadensis was the most observed, followed by Eimeria bovis and Eimeria zuernii. The statistical analysis showed an association between the age of the calves (5 to 9 months), the presence of other animals, the physiographic regions and the restricted type of husbandry with the presence of Eimeria spp. in calves (P<0.05). Protective risk factors, such as: routine coprological analysis was also associated with a decrease in infection. These data demonstrate the presence of coccidia in cattle from the State of Veracruz, additionally to the necessary measures that must be taken to control this parasitosis.

The diversity of Eimeria spp. in cattle in the Brazilian Semiarid region

The aim of the present study was to find out the diversity of Eimeria species in cattle herds in the semiarid region of Brazil. Forty cattle fecal samples were collected from 20 farms in the Paraíba State, Northeast Brazil, and examined by centrifugation-floatation technique in sucrose solution. From each positive animal, 20 oocysts were photographed and measured. Infection by Eimeria spp. was detected in 17.12% (137/800) of the samples analyzed. All the farms had at least one animal that was positive for Eimeria spp. (100%; 20/20). In total, 2740 coccidia were photographed and measured. The species detected were: Eimeria bovis (35.1%); Eimeria canadensis (17.48%); Eimeria auburnensis (14.7%); Eimeria ellipsoidalis (9.7%); Eimeria zuernii (7.22%); Eimeria brasiliensis (4.56%); Eimeria bukidnonensis (3.97%); Eimeria illinoisensis (2.91%); Eimeria wyomingensis (1.42%); Eimeria alabamensis (1.27%); Eimeria cylindrica (0.76%); Eimeria pellita (0.54%); Eimeria ildefonsoi (0.21%); and Eimeria subspherica (0.07%). It was concluded that cattle in the semiarid region of Brazil were parasitized by 14 species of Eimeria. It is thinked that the sanitary management employed, as well as the system used for raising these animals, is the crucial point that leads to high rates of infection in this region.

Eimeria infections in domestic and wild ruminants with reference to control options in domestic ruminants

Eimeria infections are commonly seen in a variety of mammalian hosts. This genus of unicellular sporozoan parasites causes significant disease (coccidiosis) in different livestock species leading to economic losses for agricultural producers. Especially the production of cattle, sheep, and goat is strongly dependent on efficient coccidiosis control. However, many other livestock hosts like, e.g., camelids, bison, rabbits, and guinea pigs may benefit from reduced parasite transmission and targeted control measures as well. Besides livestock, also wildlife and pet animals may be affected by Eimeria infections resulting in clinical or subclinical coccidiosis. Wildlife herd health is crucial to conservation efforts, and Eimeria species are a prevalent pathogen in multiple mammalian wildlife species. This review aims to highlight the epidemiology of mammalian Eimeria infections in both wild and domestic ruminants, including host specificity, transmission, survival of environmental oocysts, occurrence, and risk factors for infection. Understanding general drivers of Eimeria infection may support adequate livestock and wildlife management. Furthermore, control options for livestock with reference to management factors, drug application, and alternative approaches are discussed. The goal of Eimeria control should be to reduce pathogen transmission in different host species and to improve sustainable livestock production. Controlling Eimeria infections in livestock is important considering both their animal welfare impact and their high economic relevance.

Prevalence and risk factors of Eimeria spp. natural infection in sheep from northern Paraná, Brazil

The present study aimed to perform an epidemiological and morphological identification of Eimeria infection in sheep in Brazil. Fecal samples from sheep were collected from 20 farms in northern Paraná, Brazil. An epidemiological questionnaire was used to evaluate the risk factors. Fecal samples containing oocysts per gram of feces (OoPG) ≥1000 were subjected to the modified Willis-Mollay method to perform oocyst identification. Sporulated oocysts were observed microscopically for morphological identification. A total of 807 fecal samples were collected. Based on the morphological characteristics of the sporulated oocysts, 10 species of Eimeria were identified, with main species observed: Eimeira ovinoidalis (98.1%), Eimeria crandallis (87.6%), Eimeria parva (79.1%), and Eimeria bakuensis (60.8%). Only 2.6% (7/268) of the sheep were infected with a single species, 4.8% (13/268) contained two different species, and 92.5% (248/268) were infected with three or more species. The analysis of risk factors showed that an intensive rearing, no rotation of pasture, dirt, and slatted floors, and age up to 12 months were associated with infection. This study showed a high prevalence of Eimeria natural infection in sheep from northern Paraná, Brazil. Furthermore, based on the risk factors, good management and hygiene practices must be employed to avoid infection.

The in vitro and in vivo anti-virulent effect of organic acid mixtures against Eimeria tenella and Eimeria bovis

Eimeria tenella and Eimeria bovis are complex parasites responsible for the condition of coccidiosis, that invade the animal gastrointestinal intestinal mucosa causing severe diarrhoea, loss of appetite or abortions, with devastating impacts on the farming industry. The negative impacts of these parasitic infections are enhanced by their role in promoting the colonisation of the gut by common foodborne pathogens. The aim of this study was to test the anti-Eimeria efficacy of maltodextrin, sodium chloride, citric acid, sodium citrate, silica, malic acid, citrus extract, and olive extract individually, in vitro and in combination, in vivo. Firstly, in vitro infection models demonstrated that antimicrobials reduced (p < 0.05), both singly and in combination (AG), the ability of E. tenella and E. bovis to infect MDBK and CLEC-213 epithelial cells, and the virulence reduction was similar to that of the anti-coccidial drug Robenidine. Secondly, using an in vivo broiler infection model, we demonstrated that AG reduced (p = 0.001) E. tenella levels in the caeca and excreted faeces, reduced inflammatory oxidative stress, improved the immune response through reduced ROS, increased Mn-SOD and SCFA levels. Levels of IgA and IgM were significantly increased in caecal tissues of broilers that received 0.5% AG and were associated with improved (p < 0.0001) tissue lesion scores. A prophylactic approach increased the anti-parasitic effect in vivo, and results indicated that administration from day 0, 5 and 10 post-hatch reduced tissue lesion scores (p < 0.0001) and parasite excretion levels (p = 0.002). Conclusively, our in vitro and in vivo results demonstrate that the natural antimicrobial mixture (AG) reduced parasitic infections through mechanisms that reduced pathogen virulence and attenuated host inflammatory events.

Eimeria bovis Macromeront Formation Induces Glycolytic Responses and Mitochondrial Changes in Primary Host Endothelial Cells

Eimeria bovis is an intracellular apicomplexan parasite that causes considerable economic losses in the cattle industry worldwide. During the first merogony, E. bovis forms large macromeronts with >140,000 merozoites I in host endothelial cells. Because this is a high-energy demanding process, E. bovis exploits the host cellular metabolism to fulfill its metabolic requirements. We here analyzed the carbohydrate-related energetic metabolism of E. bovis–infected primary bovine umbilical vein endothelial cells during first merogony and showed that during the infection, E. bovis–infected culture presented considerable changes in metabolic signatures, glycolytic, and mitochondrial responses. Thus, an increase in both oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) were found in E. bovis–infected host cells indicating a shift from quiescent to energetic cell status. Enhanced levels of glucose and pyruvate consumption in addition to increased lactate production, suggesting an important role of glycolysis in E. bovis–infected culture from 12 days p.i. onward. This was also tested by glycolytic inhibitors (2-DG) treatment, which reduced the macromeront development and diminished merozoite I production. As an interesting finding, we observed that 2-DG treatment boosted sporozoite egress. Referring to mitochondrial activities, intracellular ROS production was increased toward the end of merogony, and mitochondrial potential was enhanced from 12 d p. i. onward in E. bovis–infected culture. Besides, morphological alterations of membrane potential signals also indicated mitochondrial dysfunction in macromeront-carrying host endothelial culture.

Canine Angiostrongylus vasorum-Induced Early Innate Immune Reactions Based on NETs Formation and Canine Vascular Endothelial Cell Activation In Vitro

Simple Summary

Angiostrongylus vasorum is a cardiopulmonary nematode that affects canids, residing in the pulmonary artery and right atrium/ventricle. Due to its location, the parasite will have a close interaction with the different components of the innate immune system, including endothelial cells and polymorphonuclear neutrophils (PMN). Here we evaluated the expression of adhesion molecules of canine aortic endothelial cells (CAEC), and NETs formation by co-culture of freshly isolated canine PMN with A. vasorum L3. Overall, we found distinct inter-donor variations in adhesion molecule expression among CAEC isolates. Additionally, PMN and A. vasorum co-culture induced NETs release without affecting larval viability.

Abstract

Due to its localization in the canine blood stream, Angiostrongylus vasorum is exposed to circulating polymorphonuclear neutrophils (PMN) and the endothelial cells of vessels. NETs release of canine PMN exposed to A. vasorum infective stages (third stage larvae, L3) and early pro-inflammatory immune reactions of primary canine aortic endothelial cells (CAEC) stimulated with A. vasorum L3-derived soluble antigens (AvAg) were analyzed. Expression profiles of the pro-inflammatory adhesion molecules ICAM-1, VCAM-1, P-selectin and E-selectin were analyzed in AvAg-stimulated CAEC. Immunofluorescence analyses demonstrated that motile A. vasorum L3 triggered different NETs phenotypes, with spread NETs (sprNETs) as the most abundant. Scanning electron microscopy confirmed that the co-culture of canine PMN with A. vasorum L3 resulted in significant larval entanglement. Distinct inter-donor variations of P-selectin, E-selectin, ICAM-1 and VCAM-1 gene transcription and protein expression were observed in CAEC isolates which might contribute to the high individual variability of pathological findings in severe canine angiostrongylosis. Even though canine NETs did not result in larval killing, the entanglement of L3 might facilitate further leukocyte attraction to their surface. Since NETs have already been documented as involved in both thrombosis and endothelium damage events, we speculate that A. vasorum-triggered NETs might play a critical role in disease outcome in vivo.

The Role of TLR2 and TLR4 in Recognition and Uptake of the Apicomplexan Parasite Eimeria bovis and Their Effects on NET Formation

BACKGROUND

Bovine polymorphonuclear neutrophils (PMN) constitutively express the Toll-like receptors (TLRs) TLR2 and TLR4 and have been shown to generate Neutrophil extracellular traps (NETs) upon exposure to Eimeria bovis. The present work investigated the role of TLR2 and TLR4 in the recognition and uptake of E. bovis sporozoites, IL-8 production and neutrophil extracellular trap (NET) formation.

METHODS

TLR expression was performed by flow cytometric analysis on PMN exposed to live carboxyfluorescein succinimidyl ester (CFSE)-stained sporozoites. Supernatants of PMN exposed to different E. bovis sporozoite preparations and antigens in the absence or presence of TLR antibodies were assessed for IL-8 secretion. Cells were exposed to sporozoite preparations and assessed for the activation of transcription factor NF-κB using a luciferase reporter assay. Immunofluorescence analysis was done to investigate TLR2 and TLR4 surface expression and NET formation on bovine PMN exposed to vital sporozoites.

RESULTS

we observed significantly increased TLR2 and TLR4 expression with a mean increase in expression that was greater for TLR2 than TLR4. This upregulation neither inhibited nor promoted sporozoite phagocytosis by bovine PMN. Live sporozoites together with anti-TLR2 mAb resulted in a significant enhancement of IL-8 production. NF-κB activation was more strongly induced in TLR2-HEK cells than in TLR4/MD2-HEK cells exposed to heat-killed sporozoites and antigens. Immunofluorescence analysis showed TLR-positive signals on the surface of PMN and concomitant NET formation.

CONCLUSIONS

This is the first report on E. bovis-induced concomitant TLR2 and TLR4 expression during bovine PMN-derived NETosis.

Optimized excystation protocol for ruminant Eimeria bovis- and Eimeria arloingi-sporulated oocysts and first 3D holotomographic microscopy analysis of differing sporozoite egress

Successful excystation of sporulated Eimeria spp. oocysts is an important step to acquire large numbers of viable sporozoites for molecular, biochemical, immunological and in vitro experiments for detailed studies on complex host cell-parasite interactions. An improved method for excystation of sporulated oocysts and collection of infective E. bovis- and E. arloingi-sporozoites is here described. Eimeria spp. oocysts were treated for at least 20 h with sterile 0.02 M _L-cysteine HCl/0.2 M NaHCO₃ solution at 37 °C in 100% CO₂ atmosphere. The last oocyst treatment was performed with a 0.4% trypsin 8% sterile bovine bile excystation solution, which disrupted oocyst walls with consequent activation of sporozoites within oocyst circumplasm, thereby releasing up to 90% of sporozoites in approximately 2 h of incubation (37 °C) with a 1:3 (oocysts:sporozoites) ratio. Free-released sporozoites were filtered in order to remove rests of oocysts, sporocysts and non-sporulated oocysts. Furthermore, live cell imaging 3D holotomographic microscopy (Nanolive®) analysis allowed visualization of differing sporozoite egress strategies. Sporozoites of both species were up to 99% viable, highly motile, capable of active host cell invasion and further development into trophozoite- as well as macroment-development in primary bovine umbilical vein endothelial cells (BUVEC). Sporozoites obtained by this new excystation protocol were cleaner at the time point of exposure of BUVEC monolayers and thus benefiting from the non-activation status of these highly immunocompetent cells through debris. Alongside, this protocol improved former described methods by being is less expensive, faster, accessible for all labs with minimum equipment, and without requirement of neither expensive buffer solutions nor sophisticated instruments such as ultracentrifuges.

First database of the spatial distribution of Eimeria species of cattle, sheep and goats in Mexico

Ruminant coccidiosis is a gastrointestinal disease caused by parasites of the genus Eimeria. Environmental and climatic factors are relevant for the development, survival, and transmission of coccidiosis because Eimeria oocysts are able to survive in the environment for several weeks or months in favorable conditions of moderate heat and moisture. The aim of the present study was to georeference, for the first time, the locations of Eimeria occurrences in Mexico from 1961 to 2018. A dataset was created for 3414 reports of Eimeria occurrences in cattle, sheep, and goats in Mexico. Twelve species of Eimeria that infect cattle were recorded, 11 Eimeria species of sheep are present in Mexico, and eight species of goats are geographically distributed in the country. In the current findings, it has been observed that Eimeria colonizes mainly the temperate semihumid, temperate humid, warm humid, and warm semihumid areas during spring and summer in animals younger than 1 year of age. Macroenvironmental variables like temperature and rainfall influence the prevalence of Eimeria in cattle, sheep, and goats, and for some species, the rearing system, facility type, farm size, and altitude affect the occurrence of this parasite. Results may support future studies aimed at reducing the disease prevalence of the parasite in endemic regions of Mexico. The use of recorded cases and climate variables yields a more comprehensive perspective of the epidemiology of eimeriosis, which would be difficult to infer from laboratory studies alone.

Epidemiological survey and risk factor analysis on Eimeria infections in calves and young cattle up to 1 year old in Colombia

A large-scale cross-sectional epidemiological study was conducted to evaluate prevalence, species diversity, and associated risk factors of Eimeria infections in 55 cattle farms across seven states of Colombia, including subtropical and tropical regions. In total, 1333 fecal samples from young animals (< 1 year of age) were examined at a single sampling date from August 2016 to December 2016. Flotation and McMaster techniques were conducted for parasitological investigation. Excreted Eimeria oocysts were allowed to sporulate in vitro and thereafter identified to species level based on morphological and morphometric characteristics. The overall Eimeria prevalence was 75.5% (1006/1333), with no difference observed between age categories. In total, 13 different Eimeria species were identified. The most prevalent species was E. bovis (33.5%), followed by E. auburnensis (12.5%) and E. zuernii (11.9%). Analysis of extrinsic associated risk factors revealed the floor type, feeding system, watering system, and herd size as significant (p < 0.05) risk factors for Eimeria spp. infections. Based on these data, it can be assumed that bovine coccidiosis infections occur ubiquitously in the country and might play an important role especially in its subclinical form by affecting production parameters in conventional cattle management systems.

Pinniped- and Cetacean-Derived ETosis Contributes to Combating Emerging Apicomplexan Parasites (Toxoplasma gondii, Neospora caninum) Circulating in Marine Environments

Leukocytes play a major role in combating infections either by phagocytosis, release of antimicrobial granules, or extracellular trap (ET) formation. ET formation is preceded by a certain leukocyte cell death form, known as ETosis, an evolutionarily conserved mechanism of the innate immune system also observed in marine mammals. Besides several biomolecules and microbial stimuli, marine mammal ETosis is also trigged by various terrestrial protozoa and metazoa, considered nowadays as neozoan parasites, which are circulating in oceans worldwide and causing critical emerging marine diseases. Recent studies demonstrated that pinniped- and cetacean-derived polymorphonuclear neutrophils (PMNs) and monocytes are able to form different phenotypes of ET structures composed of nuclear DNA, histones, and cytoplasmic peptides/proteases against terrestrial apicomplexan parasites, e.g., Toxoplasma gondii and Neospora caninum. Detailed molecular analyses and functional studies proved that marine mammal PMNs and monocytes cast ETs in a similar way as terrestrial mammals, entrapping and immobilizing T. gondii and N. caninum tachyzoites. Pinniped- and cetacean leukocytes induce vital and suicidal ETosis, with highly reliant actions of nicotinamide adenine dinucleotide phosphate oxidase (NOX), generation of reactive oxygen species (ROS), and combined mechanisms of myeloperoxidase (MPO), neutrophil elastase (NE), and DNA citrullination via peptidylarginine deiminase IV (PAD4).This scoping review intends to summarize the knowledge on emerging protozoans in the marine environment and secondly to review limited data about ETosis mechanisms in marine mammalian species.

Chicken endothelial cells are highly responsive to viral innate immune stimuli and are susceptible to infections with various avian pathogens

It is well established that the endothelium plays a prominent role in the pathogenesis of various infectious diseases in mammals. However, little is known about the role of endothelial cells (EC) as targets for avian pathogens and their contribution to the pathogenesis of infectious diseases in galliform birds. First, we explored the innate immune response of primary chicken aortic endothelial cells (pchAEC), obtained from 18-day-old embryos, to stimulation with pathogen-associated molecular patterns or recombinant chicken interferons (type I, II and III IFNs). In spite of the abundant expression of a number of innate immune receptors, marked cytokine responses to stimulation with pathogen-associated molecular patterns were only seen in pchAEC treated with the TLR3 agonist polyI:C (pI:C) and the MDA5 agonist liposome-complexed polyI:C (L-pI:C), as was assessed by quantitative PCR and luciferase-based IFN-I/NFκB reporter assays. Treatments of pchAEC with IFN-α, IFN-γ and IFN-λ resulted in STAT1-phosphorylation/activation, as was revealed by immunoblotting. Next, we demonstrated that pchAEC are susceptible to infection with a variety of poultry pathogens, including Marek's disease virus (MDV), infectious bursal disease virus (IBDV), avian pathogenic Escherichia coli (APEC) and Eimeria tenella. Our data highlight that chicken EC are potential targets for viral, bacterial and protozoan pathogens in gallinaceous poultry and may partake in the inflammatory and antimicrobial response. The pchAEC infection model used herein will allow further studies interrogating avian pathogen interactions with vascular EC. RESEARCH HIGHLIGHTS Use of a well-defined primary chicken aortic endothelial cell (pchAEC) culture model for studying avian host-pathogen interactions. pchAEC are responsive to innate immune stimulation with viral pathogen-associated molecular patterns and chicken type I, II and III interferons. pchAEC are susceptible to infections with economically important poultry pathogens, including MDV, IBDV, APEC and Eimeria tenella.

Artemisinin and Artemisia annua leaves alleviate Eimeria tenella infection by facilitating apoptosis of host cells and suppressing inflammatory response

Evasion strategies of intracellular parasites by hijacking cellular pathways, are necessary to ensure successful survival and replication. Eimeria tenella (E. tenella) has the ability to circumvent apoptosis of infected cells through increased expression of the transcriptional factor NF-κB and the anti-apoptotic factor Bcl-x_L during the development of second generation schizonts. Artemisinin (ART) and its original plant, the dried leaves of Artemisia annua (LAA) have been shown to be effective against avian coccidiosis, however, the underlying mechanism remains unclear. We showed that E. tenella infection promoted the expression of anti-apoptotic protein Bcl-2 and inhibited the expression of pro-apoptotic proteins Bax and cleaved caspase-3 at 60 h post infection (PI), with a higher ratio of Bcl-2 to Bax. Nevertheless, the expression trends of Bcl-2, Bax and caspase-3 were reversed at 120 h and 192 h PI. ART treatment significantly abrogated Bcl-2 expression, whereas it promoted the expression levels of Bax and cleaved caspase-3 at the three time points above. Additionally, ART remarkably suppressed the increased mRNA expressions of NF-κB and interleukin-17A in ceca during infection by E. tenella. Compared with the ART treatment, LAA treatment exerted more improvements in clinical symptoms, promoting apoptosis and suppressing inflammatory response. These alterations caused by ART and LAA treatments were consistent with the reduced clinical diarrhea and pathological improvements in chicken ceca. Collectively, these results indicate that the inhibitory effects of ART or LAA on E. tenella infection may work through facilitating the apoptosis of infected host cells and inhibiting the inflammatory response.

Occurrence of endoparasites in wild Antillean manatees (Trichechus manatus manatus) in Colombia

The recognized impact of parasites in wildlife populations demands surveillance of endangered species like the Antillean manatees (Trichechus manatus manatus) in Colombia. We conducted a parasitological survey in four rescued sea cows in order to document the parasite diversity of this sirenian in the Caribbean wetland of Colombia and contribute to the molecular characterization of its trematodes. The flukes Chiorchis fabaceus, Nudacotyle undicola and the protozoans Eimeria manatus and E. nodulosa were identified in analysed faecal samples. For C. fabaceus and N. undicola, partial regions of ribosomal RNA genes were amplified and sequenced in order to infer their phylogenetic relations. The current study constitutes a new sirenian host (T. manatus manatus) record for the genus Eimeria and the trematode N. undicola.

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Gastrointestinal parasites of the Antillean manatee of Caribbean wetland in Colombia.

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First report of Eimeria species and N. undicola in the Antillean manatee (T. manatus manatus).

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First contribution to the phylogenetic knowledge of trematode parasites of manatees.

A newly described strain of Eimeria arloingi (strain A) belongs to the phylogenetic group of ruminant-infecting pathogenic species, which replicate in host endothelial cells in vivo

Coccidiosis caused by Eimeria species is an important disease worldwide, particularly in ruminants and poultry. Eimeria infection can result in significant economic losses due to costs associated with treatment and slower growth rates, or even with mortality of heavily infected individuals. In goat production, a growing industry due to increasing demand for caprine products worldwide, coccidiosis is caused by several Eimeria species with E. arloingi and E. ninakohlyakimovae the most pathogenic. The aims of this study were genetic characterization of a newly isolated European E. arloingi strain (A) and determination of phylogenetic relationships with Eimeria species from other ruminants. Therefore, a DNA sequence of E. arloingi strain (A) containing 2290 consensus nucleotides (the majority of 18S rDNA, complete ITS-1 and 5.8S sequences, and the partial ITS-2) was amplified and phylogenetic relationship determined with the most similar sequences available on GenBank. The phylogenetic tree presented a branch constituted by bovine Eimeria species plus E. arloingi, and another one exclusively populated by ovine Eimeria species. Moreover, E. arloingi, E. bovis and E. zuernii, which all replicate in host intestinal endothelial cells of the lacteals, were found within the same cluster. This study gives new insights into the evolutionary phylogenetic relationships of this newly described caprine Eimeria strain and confirmed its close relationship to other highly pathogenic ruminant Eimeria species characterized by macromeront formation in host endothelial cells of the central lymph capillaries of the small intestine.

Molecular analyses on Neospora caninum-triggered NETosis in the caprine system

Neospora caninum is an obligate intracellular protozoan parasite causing serious reproductive disorders in large and small ruminants worldwide. Polymorphonuclear neutrophils (PMN) react against multiple invading pathogens through different mechanisms including the release of neutrophil extracellular traps (NETs). Here, in vitro interactions of caprine PMN and N. caninum tachyzoites were studied. Scanning electron microscopic- and immunofluorescence-analyses demonstrated that caprine PMN undergo NETosis upon contact with tachyzoites of N. caninum, extruding filaments that entrap parasites. Detailed co-localization studies of N. caninum tachyzoite-induced NETs revealed the presence of PMN-derived DNA being decorated with histones (H1, H2A/H2B, H3,H4) and neutrophil elastase (NE) corroborating the molecular characteristics of classical mammalian NETs. As a new result for parasite-induced NETosis, we identified pentraxin and cathepsin B in N. caninum-triggered NETs. Nonetheless, functional inhibition assays revealed that during caprine NET formation triggered by N. caninum different molecular signaling pathways are induced, when compared to other apicomplexan parasites or host species. As such, N. caninum-induced NETosis appears to be influenced by MPO but independent of NADPH oxidase, SOCE, ERK1/2 and p38 MAPK activities. Furthermore, the inhibition of PMN autophagy via blockage of the PI3K-mediated signaling pathway failed to influence tachyzoite-induced NETosis. Since N. caninum-tachyzoites induced caprine NETosis, this effector mechanism should be considered as an early host immune response during acute caprine neosporosis.

Eimeria ninakohlyakimovae induces NADPH oxidase-dependent monocyte extracellular trap formation and upregulates IL-12 and TNF-α, IL-6 and CCL2 gene transcription

Extracellular trap (ET) formation has been demonstrated as novel effector mechanism against diverse pathogens in polymorphonuclear neutrophils (PMN), eosinophils, mast cells, macrophages and recently also in monocytes. In the current study, we show that E. ninakohlyakimovae triggers the deliverance of monocyte-derived ETs in vitro. Fluorescence illustrations as well as scanning electron microscopy (SEM) analyses showed that monocyte-derived ET formation was rapidly induced upon exposure to viable sporozoites, sporocysts and oocysts of E. ninakohlyakimovae. Classical features of monocyte-released ETs were confirmed by the co-localization of extracellular DNA adorned with myeloperoxidase (MPO) and histones (H3) in parasite-entrapping structures. The treatment of caprine monocyte ET structures with NADPH oxidase inhibitor diphenylene iodondium (DPI) significantly reduced ETosis confirming the essential role of reactive oxygen species (ROS) in monocyte mediated ETs formation. Additionally, co-culture of monocytes with viable sporozoites and soluble oocyst antigen (SOA) induced distinct levels of cytokine and chemokine gene transcription. Thus, the transcription of genes encoding for IL-12 and TNF-α was significantly upregulated after sporozoite encounter. In contrast IL-6 and CCL2 gene transcripts were rather weakly induced by parasites. Conversely, SOA only induced the up-regulation of IL-6 and CCL2 gene transcription, and failed to enhance transcripts of IL-12 and TNF-α in vitro. We here report on monocyte-triggered ETs as novel effector mechanism against E. ninakohlyakimovae. Our results strongly suggest that monocyte-mediated innate immune reactions might play an important role in early host immune reactions against E. ninakohlyakimovae in goats.

Apicomplexans pulling the strings: manipulation of the host cell cytoskeleton dynamics

Invasive stages of apicomplexan parasites require a host cell to survive, proliferate and advance to the next life cycle stage. Once invasion is achieved, apicomplexans interact closely with the host cell cytoskeleton, but in many cases the different species have evolved distinct mechanisms and pathways to modulate the structural organization of cytoskeletal filaments. The host cell cytoskeleton is a complex network, largely, but not exclusively, composed of microtubules, actin microfilaments and intermediate filaments, all of which are modulated by associated proteins, and it is involved in diverse functions including maintenance of cell morphology and mechanical support, migration, signal transduction, nutrient uptake, membrane and organelle trafficking and cell division. The ability of apicomplexans to modulate the cytoskeleton to their own advantage is clearly beneficial. We here review different aspects of the interactions of apicomplexans with the three main cytoskeletal filament types, provide information on the currently known parasite effector proteins and respective host cell targets involved, and how these interactions modulate the host cell physiology. Some of these findings could provide novel targets that could be exploited for the development of preventive and/or therapeutic strategies.

Targeting essential Eimeria ninakohlyakimovae sporozoite ligands for caprine host endothelial cell invasion with a phage display peptide library

Eimeria ninakohlyakimovae is an important coccidian parasite of goats which causes severe diarrhoea in young animals. Specific molecules that mediate E. ninakohlyakimovae host interactions and molecular mechanisms involved in the pathogenesis are still unknown. Although strong circumstantial evidence indicates that E. ninakohlyakimovae sporozoite interactions with caprine endothelial host cells (ECs) are specific, hardly any information is available about the interacting molecules that confer host cell specificity. In this study, we describe a novel method to identify surface proteins of caprine umbilical vein endothelial cells (CUVEC) using a phage display library. After several panning rounds, we identified a number of peptides that specifically bind to the surface of CUVEC. Importantly, caprine endothelial cell peptide 2 (PCEC2) and PCEC5 selectively reduced the infection rate by E. ninakohlyakimovae sporozoites. These preliminary data give new insight for the molecular identification of ligands involved in the interaction between E. ninakohlyakimovae sporozoites and host ECs. Further studies using this phage approach might be useful to identify new potential target molecules for the development of anti-coccidial drugs or even new vaccine strategies.

Suitable in vitro culture of Eimeria bovis meront II stages in bovine colonic epithelial cells and parasite-induced upregulation of CXCL10 and GM-CSF gene transcription

We here established a suitable in vitro cell culture system based on bovine colonic epithelial cells (BCEC) for the development of Eimeria bovis merozoites I and the characterization of early parasite-induced innate epithelial host cell reactions as gene transcription of proinflammatory molecules. Both primary and permanent BCEC (BCEC (rim) and BCEC(perm)) were suitable for E. bovis merozoite I invasion and subsequent development of meronts II leading to the release of viable merozoites II. E. bovis merozoite II failed to develop any further neither into gamont nor oocyst stages in BCEC in vitro. E. bovis merozoite I induced innate epithelial host cell reactions at the level of CXC/CCL chemokines (CXCL1, CXCL8, CXCL10, CCL2), IL-6, and GM-CSF gene transcription. Overall, both BCEC types were activated by merozoite I infections since they showed significantly enhanced gene transcript levels of the immunomodulatory molecules CXCL10 and GM-CSF. However, gene transcription profiles of BCEC(prim) and BCEC(perm) revealed different reaction patterns in response to merozoite I infection with regard to quality and kinetics of chemokine/cytokine gene transcription. Although both BCEC types equally showed most prominent responses for CXCL10 and GM-CSF, the induction of CXCL1, CXCL8, CCL2, and IL-6 gene transcripts varied qualitatively and quantitatively. Our results demonstrate that BCEC seem capable to respond to E. bovis merozoite I infection by the upregulation of CXCL10 and GM-CSF gene transcription and therefore probably contribute to host innate effector mechanisms against E. bovis.

Besnoitia besnoiti tachyzoites induce monocyte extracellular trap formation

Extracellular trap (ET) formation has been demonstrated as an important novel effector mechanism of polymorphonuclear neutrophils (PMN), eosinophils, mast cells and macrophages acting extracellularly against pathogens. In the present study, we show that tachyzoites of the emerging apicomplexan parasite Besnoitia besnoiti, that have recently been reported as potent inducers of PMN-derived ETosis, also trigger the release of ETs in an additional cell type, namely in monocytes. Fluorescence illustrations as well as scanning electron microscopy analyses (SEM) showed monocyte-promoted ET formation to be rapidly induced upon exposure to viable tachyzoites of B. besnoiti. Classical characteristics of ETs were confirmed by the co-localization of extracellular DNA with histones (H3) or myeloperoxidase (MPO) in parasite-entrapping structures. Monocyte-derived ETs were efficiently abolished by DNase I treatment and significantly reduced by treatments with inhibitors of MPO and NADPH oxidase, thus strengthening the key roles of reactive oxygen species (ROS) and MPO in monocyte ET formation. For comparative reasons, we additionally tested sporozoite stages of the closely related parasite Eimeria bovis for their capacity to induce monocyte-derived ETs and showed that these stages indeed induce ETs. To our best knowledge, we here report for the first time on monocyte ETs against the apicomplexan parasites B. besnoiti and E. bovis. Our results indicate that monocyte-triggered ETs may represent an important effector mechanism of the host early innate immune response against B. besnoiti and add a new cell type to the list of cells capable to release ETs.

The intriguing host innate immune response: novel anti-parasitic defence by neutrophil extracellular traps

The capacity of polymorphonuclear neutrophils (PMN) and other leucocytes of the innate immune system to expel their DNA in a controlled process into the extracellular environment to trap and kill pathogenic microorganisms led to a paradigm shift in our comprehension of host leucocyte-pathogen interactions. Formation of neutrophil extracellular traps (NETs) has recently been recognized as a novel effector mechanism of the host innate immune response against microbial infections. Meanwhile evidence has arisen that NET formation is a widely spread mechanism in vertebrates and invertebrates and extends not only to the entrapment of microbes, fungi and viruses but also to the capture of protozoan and metazoan parasites. PMN produce NETs after stimulation with mitogens, cytokines or pathogens in a controlled process which depends on reactive oxygen species (ROS) and the induction of the Raf-MEK-ERK-mediated signalling pathway cascade. NETs consist of nuclear DNA as a backbone decorated with histones, antimicrobial peptides, and PMN-specific granular enzymes thereby providing an extracellular matrix capable of entrapping and killing invasive pathogens. This review is intended to summarize parasite-related data on NETs. Special attention will be given to NET-associated mechanisms by which parasites, in particular apicomplexa, might be hampered in their ability to reproduce within the host cell and complete the life cycle.

Induced metabolic disturbance and growth depression in rabbits infected with Eimeria coecicola

Eimeria coecicola causes intestinal coccidiosis in rabbits and, thereby, enormous economic losses in rabbit farms. This study aimed to investigate the effect of intestinal coccidial infection, E. coecicola on metabolic status and growth of rabbits. Animals were allocated into two groups with eight rabbits each; one group was orally inoculated with saline and served as control while the other group was orally inoculated with 5 × 10(4) sporulated oocysts. On day 7 postinfection, fecal expulsion of E. coecicola oocysts is maximal (1.2 × 10(6) oocyst/g feces) and rabbits have lost approximately 23% of their weight. Infection induced a severe depletion in plasma growth hormone level. In addition, the energy metabolic status was significantly (P ≤ 0.05) altered by the infection as, both blood glucose and total lipid levels were significantly elevated with mutual depletion in carbohydrate stores in liver sections. Also, the thyroid-stimulating hormone and cortisol concentrations were raised as a consequence of the infection. Moreover, protein status was affected by the infection as both liver and plasma total proteins were significantly decreased with concurrent disturbance in the blood protein electrophoretic pattern and duplication of blood urea nitrogen concentration. Finally, the infection induced plasma electrolyte imbalance as indicated by a significant decrease in sodium, potassium, calcium, phosphorus, ferrous, and selenium ions. Our data suggested that the intestinal coccidial infection of rabbits with E. coecicola has serious effects on rabbit growth and metabolism and could disrupt endocrine and electrolyte homeostasis.