Explore the vast range of titles available.

Coccidiosis is a parasitic disease caused by Eimeria spp., and the emergence of drug resistance has seriously affected the control of the disease. Using RNA-seq, we previously found that phosphoglycerate kinase of Eimeria tenella ( Et PGK) was differentially downregulated in diclazuril-resistant (DZR) and maduramicin-resistant (MRR) strains compared with drug-sensitive (DS) strain. In this study, we further analysed the characteristics and functions of Et PGK to find the possible mechanism of drug resistance of E. tenella . Quantitative real-time PCR (qRT-PCR) and western blot found that Et PGK was highly expressed in sporulated oocysts, followed by sporozoites and second-generation merozoites of E. tenella . Indirect immunofluorescence localization showed that Et PGK was located mainly in the cytoplasm and on the surface of the parasites. Invasion inhibition assays showed that anti-r Et PGK antibody significantly inhibited the invasion of parasites. Further studies using qRT-PCR and western blot found that the transcription and translation levels of Et PGK were downregulated in both resistant (DZR and MRR) strains compared with the DS strain, and the transcription level correlated negatively with the drug concentration. The enzyme activity assay revealed that Et PGK enzyme activity was decreased in the DZR strain compared with the DS strain. qRT-PCR revealed that the mRNA transcription level of Et PGK was significantly downregulated in the field DZR strain and salinomycin-resistant strain compared with the DS strain. These results suggested that Et PGK has other important roles that are separate and distinct from its function in glycolysis, and it might be involved in the development of drug resistance of E. tenella .

Sixty billion chickens are produced worldwide each year, and all are at risk from Eimeria , parasites that cause coccidiosis. Control relies widely on chemoprophylaxis, but pressure to reduce drug use in farming urges development of cost-effective vaccines. Antigens such as apical membrane antigen 1 (AMA1) offer promise as anticoccidial vaccine candidates, but experience with related apicomplexans such as Plasmodium , in which pre-existing antigenic diversity and incompatible population structure have undermined vaccine development, tempers confidence. Parasite genotyping identified enormous region-specific variation in haplotype diversity for Eimeria tenella but a contrastingly low level of polymorphism for Et AMA1. Although high levels of polyclonal Eimeria infection and hybridization indicate an ability to disseminate vaccine resistance rapidly, the low level of Et AMA1 diversity promotes vaccine development. The phylum Apicomplexa includes serious pathogens of humans and animals. Understanding the distribution and population structure of these protozoan parasites is of fundamental importance to explain disease epidemiology and develop sustainable controls. Predicting the likely efficacy and longevity of subunit vaccines in field populations relies on knowledge of relevant preexisting antigenic diversity, population structure, the likelihood of coinfection by genetically distinct strains, and the efficiency of cross-fertilization. All four of these factors have been investigated for Plasmodium species parasites, revealing both clonal and panmictic population structures with exceptional polymorphism associated with immunoprotective antigens such as apical membrane antigen 1 (AMA1). For the coccidian Toxoplasma gondii only genomic diversity and population structure have been defined in depth so far; for the closely related Eimeria species, all four variables are currently unknown. Using Eimeria tenella , a major cause of the enteric disease coccidiosis, which exerts a profound effect on chicken productivity and welfare, we determined population structure, genotype distribution, and likelihood of cross-fertilization during coinfection and also investigated the extent of naturally occurring antigenic diversity for the E . tenella AMA1 homolog. Using genome-wide Sequenom SNP-based haplotyping, targeted sequencing, and single-cell genotyping, we show that in this coccidian the functionality of Et AMA1 appears to outweigh immune evasion. This result is in direct contrast to the situation in Plasmodium and most likely is underpinned by the biology of the direct and acute coccidian life cycle in the definitive host.

Background Poultry coccidiosis is a parasitic enteric disease with a highly negative impact on chicken production. In-feed chemoprophylaxis remains the primary method of control, but the increasing ineffectiveness of anticoccidial drugs, and potential future restrictions on their use has encouraged the use of commercial live vaccines. Availability of such formulations is constrained by their production, which relies on the use of live chickens. Several experimental approaches have been taken to explore ways to reduce the complexity and cost of current anticoccidial vaccines including the use of live vectors expressing relevant Eimeria proteins. We and others have shown that vaccination with transgenic Eimeria tenella parasites expressing Eimeria maxima Apical Membrane Antigen-1 or Immune Mapped Protein-1 ( Em AMA1 and Em IMP1) partially reduces parasite replication after challenge with a low dose of E. maxima oocysts. In the present study, we have reassessed the efficacy of these experimental vaccines using commercial birds reared at high stocking densities and challenged with both low and high doses of E. maxima to evaluate how well they protect chickens against the negative impacts of disease on production parameters. Methods Populations of E. tenella parasites expressing Em AMA1 and Em IMP1 were obtained by nucleofection and propagated in chickens. Cobb500 broilers were immunised with increasing doses of transgenic oocysts and challenged two weeks later with E. maxima to quantify the effect of vaccination on parasite replication, local IFN-γ and IL-10 responses (300 oocysts), as well as impacts on intestinal lesions and body weight gain (10,000 oocysts). Results Vaccination of chickens with E. tenella expressing Em AMA1, or admixtures of E. tenella expressing Em AMA1 or Em IMP1, was safe and induced partial protection against challenge as measured by E. maxima replication and severity of pathology. Higher levels of protection were observed when both antigens were delivered and was associated with a partial modification of local immune responses against E. maxima , which we hypothesise resulted in more rapid immune recognition of the challenge parasites. Conclusions This study offers prospects for future development of multivalent anticoccidial vaccines for commercial chickens. Efforts should now be focused on the discovery of additional antigens for incorporation into such vaccines.

Salinomycin is a polyether ionophore widely used for the treatment of coccidiosis in poultry. However, the emergence of coccidia strains resistant to salinomycin presents challenges for control efforts, and the mechanisms underlying this resistance in Eimeria remain inadequately understood. In this study, 78 stable salinomycin-resistant strains were generated through experimental evolution approaches. Whole-genome sequencing of salinomycin-resistant Eimeria tenella isolates revealed single nucleotide polymorphisms (SNPs), with 12 candidate genes harboring nonsynonymous mutations identified. To confirm the candidate gene responsible for conferring salinomycin resistance, we leveraged reverse genetic strategies and identified a key amino acid substitution (F204S) in adrenodoxin oxidoreductase ( EtADR ), which markedly reduced susceptibility to salinomycin. Our results elucidate the complex interactions among salinomycin resistance, parasite fitness, point mutations, and the structure of EtADR, laying the foundation for future studies on drug resistance in Eimeria and contributing to the development of targeted control strategies.

Chicken coccidiosis causes retarded growth and low production performance in poultry, resulting in huge economic losses to the poultry industry. In order to prevent and control chicken coccidiosis, great efforts have been made to develop new drugs and vaccines, which require pure isolates of Eimeria spp. In this study, we obtained the Eimeira tenella Xiantao isolate by single oocyst isolation technology and compared its genome with the reference genome GCF_000499545.2_ETH001 of the Houghton strain. The results of the comparative genomic analysis indicated that the genome of this isolate contained 46,888 single nucleotide polymorphisms (SNPs). There were 15,107 small insertion and deletion variations (indels), 1693 structural variations (SV), and 3578 copy number variations (CNV). In addition, 64 broilers were used to determine the resistance profile of Xiantao strain. Drug susceptibility testing revealed that this isolate was completely resistant to monensin, diclazuril, halofuginone, sulfachlorpyrazine sodium, and toltrazuril, but sensitive to decoquinate. These data improve our understanding of drug resistance in avian coccidia.

The apical complex of apicomplexan parasites is essential for host cell invasion and intracellular survival and as the site of regulated exocytosis from specialised secretory organelles called rhoptries and micronemes. Despite its importance, there are few data on the three-dimensional organisation and quantification of these organelles within the apical complex or how they are trafficked to this specialised region of plasma membrane for exocytosis. In coccidian apicomplexans there is an additional tubulin-containing hollow barrel structure, the conoid, which provides a structural gateway for this specialised apical secretion. Using a combination of cellular electron tomography and serial block face-scanning electron microscopy (SBF-SEM) we have reconstructed the entire apical end of Eimeria tenella sporozoites; we report a detailed dissection of the three- dimensional organisation of the conoid and show there is high curvature of the tubulin-containing fibres that might be linked to the unusual comma-shaped arrangement of protofilaments. We quantified the number and location of rhoptries and micronemes within cells and show a highly organised gateway for trafficking and docking of rhoptries, micronemes and microtubule-associated vesicles within the conoid around a set of intra-conoidal microtubules. Finally, we provide ultrastructural evidence for fusion of rhoptries directly through the parasite plasma membrane early in infection and the presence of a pore in the parasitophorous vacuole membrane, providing a structural explanation for how rhoptry proteins may be trafficked between the parasite and the host cytoplasm.

Avian coccidiosis, caused by the protozoan Eimeria, leads to significant economic losses for the poultry industry. In this study, bacteriophages that specifically bind to the calcium-binding protein ( Et Cab) of Eimeria tenella were selected using a biopanning process with a pIII phage display library. The recombinant Et Cab protein served as the ligand in this selection process. The binding ability of target phages to the Et Cab protein or E. tenella sporozoites was evaluated. The role of peptides corresponding to target phages in inhibiting the invasion of E. tenella sporozoites into cells was analysed using flow cytometry. Subsequently, the phages were encapsulated in sodium alginate to protect them from degradation in gastric fluid, which has a low pH value. Chickens were orally administered both microencapsulated and non-microencapsulated phages, and the protective effects against E. tenella infection were assessed. The binding mechanism of these peptides to the Et Cab protein was investigated through in silico analysis. The results indicated that three specific phages (Y, G, and V) could bind effectively to recombinant Et Cab protein as well as to sporozoite proteins. All three peptides, particularly Y and G, demonstrated significant inhibition of sporozoite invasion into cells in vitro. Additionally, oral administration of the encapsulated phages Y and G provided a higher level of protection against Eimeria infection compared to encapsulated phage V and the unencapsulated phages. Molecular docking studies revealed that three peptides, particularly Y and G, efficiently bind to the Et Cab protein through hydrogen bonds. This study provides a reference for developing small molecular drugs targeting coccidiosis.

Apical membrane antigen-1 (AMA1) is a micronemal protein of apicomplexan parasites that appears to be essential during the invasion of host cells. In this study, a full-length cDNA of AMA1 was identified from Eimeria tenella (Et) using expressed sequence tag and the rapid amplification of cDNA ends technique. EtAMA1 had an open reading frame of 1608 bp encoding a protein of 535 amino acids. Quantitative real-time PCR analysis revealed that EtAMA1 was expressed at higher levels in sporozoites than in the other developmental stages (unsporulated oocysts, sporulated oocysts and second-generation merozoites). The ectodomain sequence was expressed as recombinant EtAMA1 (rEtAMA1) and rabbit polyclonal antibodies raised against the rEtAMA1 recognized a 58-kDa native parasite protein by Western Blotting and had a potent inhibitory effect on parasite invasion, decreasing it by approximately 70%. Immunofluorescence analysis and immunohistochemistry analysis showed EtAMA1 might play an important role in sporozoite invasion and development.

Avian coccidiosis, caused by protozoan parasites of the genus Eimeria, poses a major threat to the poultry industry worldwide, leading to severe economic losses through reduced growth rates, poor feed efficiency, and increased mortality. Although the conventional management of this disease has relied on anticoccidial drugs, the overwhelming use of these agents has led to the rapid emergence and spread of drug-resistant Eimeria isolates, highlighting the urgent need for novel therapeutic approaches. This study employed computational approaches to identify novel inhibitors targeting Eimeria tenella prolyl-tRNA synthetase (EtPRS). Based on the virtual screening of a library of 3045 natural compounds, 42 high-confidence inhibitors were identified. Three compounds, including Chelidonine, Bicuculline, and Guggulsterone, demonstrated strong and selective binding to EtPRS through stable interactions within the active site. ADMET predictions revealed favorable safety profiles, while molecular dynamic simulations confirmed binding stability. Overall, this research established a solid framework for the development of effective anticoccidial agents targeting PRS, contributing to the advancement of therapeutic strategies for combating parasitic infections in the poultry industry.

Coccidiosis poses a significant threat to the poultry industry, with synthetic antibiotics and disinfectants being the primary tools for control. This study investigated the potential of Piper betle L essential oil (PBEO) as a natural alternative against Eimeria tenella , one of the most pathogenic Eimeria species affecting poultry. Our findings revealed that PBEO exhibits significant anticoccidial effects through two primary mechanisms: (i) oocysticidal activity by disintegrating oocyst walls and (ii) inhibition of the sporulation process. PBEO demonstrated oocysticidal activities ranging from 8.67 to 95.33% across concentrations from 0.04 to 40%. Notably, at 72 h post-incubation, a 0.04% PBEO concentration significantly reduced the number of sporulated oocysts ( P  ≤ 0.05) to 71.67%, showing effects comparable to those of formalin. PBEO reduced 50% of oocyst sporulation (IC 50 ) in the concentration of 1.31% at 72 h. Gas chromatography-mass spectrometry (GC-MS) identified the primary constituents of PBEO, including eugenol, beta-caryophyllene, and other key compounds, collectively constituting 96% of the oil. This research underscores the potential of PBEO as a natural anticoccidial agent and lays the groundwork for further studies aimed at identifying, isolating, and developing active compounds that may specifically target the sporogony process in coccidian parasites.