Explore the vast range of titles available.

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.

Eimeria species are obligate intracellular parasites that usually replicate in intestinal cells and can cause the disease coccidiosis. Coccidiosis of livestock and poultry incurs significant production losses and compromises animal welfare, with the greatest impact occurring in chicken production. Control of coccidiosis is challenging, requiring good husbandry and effective drug or live vaccine prophylaxis, and there is demand for more scalable and cost-effective vaccines. Proteins secreted from dense granules (GRAs) play crucial roles in intracellular survival in many apicomplexans, but knowledge of these organelles and their secreted proteins in Eimeria is extremely limited. In this study, we observed a reduced GRA protein repertoire encoded in Eimeria spp. genomes compared to Toxoplasma gondii (23 vs. 71) with just 12 orthologues identified in the Eimeria tenella genome. In silico analysis of three of these putative dense granule proteins - EtGRA9, EtGRA12a, and EtGRA12b - revealed the presence of signal peptides in EtGRA9 and EtGRA12b, while none was detected in EtGRA12a. Sequence analysis of E. tenella field isolates revealed a limited number of polymorphisms in the genes encoding these three proteins, suggesting purifying selection possibly related to their functional importance. In contrast, E. maxima showed greater variation, indicating relaxed selective pressure or diversifying selection. When expressed as recombinant proteins all three were recognised by sera from chickens previously infected with E. tenella . Their potential role in parasite intracellular niche formation and close interaction with the host cell makes them promising antigens for vaccine development. To evaluate this potential, EtGRA9 was expressed as a recombinant protein and used to vaccinate chickens prior to E. tenella challenge. Immunisation with recombinant EtGRA9 reduced parasite load in the caeca by 85.7%, comparable to immunisation with recombinant EtAMA1, an antigen previously shown to confer significant protection.

Background Avian coccidiosis is often caused by co-infection with several species of Eimeria worldwide. Developing a multivalent vaccine with an antigen common to multiple Eimeria species is a promising strategy for controlling clinical common co-infection of Eimeria . In the previous study, 14–3-3 was identified as one of the immunogenic common antigen in E. tenella , E. acervulina and E. maxima . The aim of the present study was to evaluate the immunogenicity and protective efficacy of Ea14–3-3 in the form of DNA vaccine against infection with three species of Eimeria both individually and simultaneously. Results After vaccination with pVAX-Ea14–3-3, the Ea14–3-3 gene was transcribed and expressed in the injected muscles. Vaccination with pVAX-Ea14–3-3 significantly increased the proportion of CD4 + and CD8 + T lymphocytes and produced a strong IgY response in immunized chickens. Similarly, pVAX-Ea14–3-3 stimulated the chicken’s splenocytes to produce high levels of Th1-type (IFN-γ, IL-2) and Th2-type (IL-4) cytokines. The vaccine-induced immune response was responsible to increase weight gain, decreased the oocyst output, and alleviated enteric lesions significantly in immunized chickens as compared to control group, in addition to induce moderate anti-coccidial index (ACI). Conclusion These results indicate that Ea14–3-3 is highly immunogenic and capable to induce significant immune responses. Furthermore, Ea14–3-3 antigen can provide effective protection against infection with Eimeria tenella , Eimeria acervulina , Eimeria maxima both individually and in combination with three Eimeria species . Significant outcomes of our study provide an effective candidate antigen for developing a multivalent Eimeria vaccine against mixed infection with various Eimeria species under natural conditions.

•In this study, novel multivalent epitope DNA vaccines were constructed and they could provide effective protection against four Eimeria species.•The multivalent epitope DNA vaccines were basing on the comprehensive consideration of mixed infection and the critical role of cellular immunity in Eimeria infection.•The criterion of selection of T-cell epitope was the comprehensive consideration of epitope prediction and protective efficacy.•Our findings suggest that the multivalent epitope DNA vaccines are the potential candidate vaccines against mixed infection of Eimeria under natural conditions. Avian coccidiosis is mostly caused by mixed infection of several Eimeria species under natural conditions and immunity to avian coccidiosis is largely dependent on T-cell immune response. In this study, 14 T-cell epitope fragments from eight antigens of Eimeria tenella (E. tenella), Eimeria necatrix (E. necatrix), Eimeria maxima (E. maxima) and Eimeria acervulina (E. acervulina) were ligated with pVAX1 producing 14 monovalent DNA vaccines, respectively. Protective immunity of the monovalent DNA vaccines was assessed by in vivo challenge experiments and then four most protective fragments of each species were chosen to construct multivalent epitope DNA vaccines with or without chicken IL-2 as genetic adjuvant. Protective efficacies of the epitope DNA vaccines on chickens against E. tenella, E. necatrix, E. maxima and E. acervulina were evaluated. The results showed that the constructed multivalent epitope DNA vaccines significantly increased body weight gain, alleviated enteric lesions and reduced oocyst output of the infected birds. Especially, the multivalent epitope DNA vaccines of pVAX1-NA4-1-TA4-1-LDH-2-EMCDPK-1 and pVAX1-NA4-1-TA4-1-LDH-2-EMCDPK-1-IL-2 not only significantly increased body weight gain, alleviated enteric lesions and reduced oocyst output of the infected birds, but also resulted in anti-coccidial index (ACI) more than 170 against E. tenella, E. necatrix, E. maxima and E. acervulina, which indicated they could induce protective immunity against E. tenella, E. necatrix, E. maxima and E. acervulina. Our findings suggest the constructed multivalent epitope DNA vaccines are the potential candidate multivalent vaccines against mixed infection of Eimeria.

Background Live anticoccidial vaccines have been a tremendous success for disease prevention. The establishment of the reverse genetic manipulation platform has enabled the development of Eimeria parasites, the live anticoccidial vaccine strains, as vaccine vectors. In our previous study, recombinant E. tenella expressing a single immunodominant antigen of E. maxima (Et-EmIMP1) was able to protect chickens against challenge infection with E. maxima . This promising result encouraged us to further explore strategies to improve the protection efficacy of recombinant Eimeria and develop it as a vaccine vector. Results We constructed a novel recombinant Eimeria line expressing apical membrane antigen 1 of E. maxima (Et-EmAMA1) and then immunized chickens with Et-EmAMA1 and/or Et-EmIMP1. We found that the E. maxima soluble antigen-specific cell-mediated immunity was much stronger in the birds that were co-immunized with Et-EmAMA1 and Et-EmIMP1 than in those that were immunized with Et-EmAMA1 or Et-EmIMP1 alone. The oocyst production after E. maxima infection was significantly reduced in the recombinant Eimeria -immunized birds compared with the wild-type-immunized and naïve birds. The oocyst production in the birds co-immunized with Et-EmAMA1 and Et-EmIMP1 was consistently the lowest among the treatment groups after E. maxima infection. Conclusions These results demonstrated that Eimeria is an effective vaccine vector that can carry and deliver heterologous Eimeria antigens to the host immune system and trigger specific immune responses. Our results also suggested that increasing the number of recombinant Eimeria lines is an effective approach to enhance protective immunity against infections with heterologous pathogens.

Control of avian coccidiosis is increasingly being achieved by the administration of low doses of Eimeria oocysts to newly hatched chicks. The purpose of this study was to test the efficacy of gel beads containing a mixture of Eimeria acervulina, Eimeria maxima, and Eimeria tenella oocysts as a vaccine to protect broilers raised in contact with litter. Newly hatched chicks were either sprayed with an aqueous suspension of Eimeria oocysts or were allowed to ingest feed containing Eimeria oocysts-incorporated gel beads. Control, 1-day-old chicks were given an equivalent number of Eimeria oocysts (103 total) by oral gavage or received no vaccine (nonimmunized controls). All chicks were raised in floor-pen cages in direct contact with litter. At 4 wk of age, all chickens and a control nonimmunized group received a high-dose E. acervulina, E. maxima, and E. tenella challenge infection. Chickens immunized with Eimeria oocysts in gel beads or by spray vaccination displayed significantly (P < 0.05) greater weight gain (WG) compared to nonimmunized controls. Feed conversion ratio (FCR) also showed a significant (P < 0.05) improvement in both groups relative to nonimmunized controls. Moreover, WG and FCR in both groups was not significantly different (P > 0.05) from chickens immunized by oral gavage or from nonimmunized, noninfected controls. Oocyst excretion after Eimeria challenge by all immunized groups was about 10-fold less than in nonimmunized controls. These findings indicate that immunization efficacy of gel beads and spray vaccination is improved by raising immunized chicks in contact with litter. Protección de los pollos contra la coccidiosis en corrales de piso mediante la administración de ooquistes de Eimeria utilizando perlas de gel o por vacunación en aerosol. El control de la coccidiosis aviar se lleva a cabo cada vez más mediante la administración de dosis bajas de oocistos de Eimeria a pollitos recién nacidos. El propósito de este estudio fue evaluar la eficacia de las perlas de gel que contienen una mezcla de ooquistes de Eimeria acervulina, Eimeria maxima y Eimeria tenella como una vacuna para proteger pollos criados sobre cama. Pollitos recién nacidos fueron ya sea sometidos a aerosoles con una suspensión acuosa de ooquistes de Eimeria o se les permitió ingerir alimentos que contenían ooquistes de Eimeria incorporados en perlas de gel. A los pollos de un día de edad del grupo control, se les administró un número equivalente de ooquistes de Eimeria (103 en total) por sonda oral o no recibieron ninguna vacuna (controles no inmunizados). Todos los pollos fueron criados en corrales en contacto directo con la cama. A las cuatro semanas de edad, todos los pollos y el grupo control no inmunizado fueron desafiados con una dosis alta de E. acervulina, E. maxima y E. tenella. Los pollos inmunizados con ooquistes de Eimeria en perlas de gel o mediante vacunación por aerosol mostraron una mayor ganancia de peso, de manera significativa (P <0.05), en comparación con los controles no inmunizados. La tasa de conversión alimenticia (FCR) también mostró una mejora significativa (P <0.05) en los dos grupos en comparación con los controles no inmunizados. Por otra parte, la ganancia de peso y la conversión alimenticia en los dos grupos no fue significativamente diferente (P> 0.05) a partir de pollos inmunizados por sonda oral o de los controles no inmunizados y no infectados. La excreción de ooquistes de Eimeria después del desafío para todos los grupos inmunizados fue aproximadamente 10 veces menos que en los controles no inmunizados. Estos hallazgos indican que la eficacia de la inmunización de perlas de gel y la vacunación por aerosol se mejora mediante el contacto de los pollos de los pollos inmunizados con la cama.

Infectious bursal disease (IBD), caused by the infectious bursal disease virus (IBDV), significantly threatens global poultry health by inducing immunosuppression and causing economic losses. To enhance vaccination efficacy, we engineered a transgenic strain of Eimeria acervulina (Ea-2C3d) expressing a fusion protein composed of IBDV VP2 and three tandem C3d segments (3C3d), utilizing C3d's adjuvant properties to boost immune responses. The transgene was generated by integrating codon-optimized VP2 and 3C3d sequences into the E. acervulina genome using restriction enzyme-mediated transfection. PCR, protein, and genome sequencing confirmed the successful integration and expression of VP2 fusion C3d, but only two copies of C3d were successfully expressed, due to a partial deletion of one C3d copy during the transfection process. In vivo studies demonstrated that Ea-2C3d elicited significantly higher anti-VP2 antibody titers than the parental Ea-VP2 strain (P < 0.05), especially following second immunization. Upon challenge with virulent IBDV, chickens immunized with Ea-2C3d displayed reduced bursal lesions (histopathological score ≤ 1) and maintained bursal integrity (bursal index >0.7), comparable to those receiving a commercial subunit vaccine. Despite reduced reproductive capacity in the transgenic parasites, Ea-2C3d maintained its immunogenicity and safety. These findings highlight that C3d adjuvant enhances VP2-mediated protection in a coccidial vector, presenting a novel dual-protection strategy against IBD and coccidiosis.

Eimeria is an intracellular obligate apicomplexan parasite that parasitizes the intestinal epithelial cells of livestock and poultry, exhibiting strong host and tissue tropism. Parasite–host interactions involve complex networks and vary as the parasites develop in the host. However, understanding the underlying mechanisms remains a challenge. Acknowledging the lack of studies on Eimeria invasion mechanism, we described the possible invasion process through comparative analysis with other apicomplexan parasites and explored the fact that parasite–host interactions serve as a prerequisite for successful recognition, penetration of the intestinal mechanical barrier, and completion of the invasion. Although it is recognized that microbiota can enhance the host immune capacity to resist Eimeria invasion, changes in the microenvironment can, in turn, contribute to Eimeria invasion and may be associated with reduced immune capacity. We also discuss the immune evasion strategies of Eimeria , emphasizing that the host employs sophisticated immune regulatory mechanisms to suppress immune evasion by parasites, thereby sustaining a balanced immune response. This review aims to deepen our understanding of Eimeria –host interactions, providing a theoretical basis for the study of the pathogenicity of Eimeria and the development of novel anticoccidial drugs.

Eimeria bovis is an important coccidian parasite that causes high economic losses in the cattle industry. We recently showed that polymorphonuclear neutrophils (PMN) react upon E. bovis sporozoite exposure by neutrophil extracellular trap (NET) formation. We focused here on the molecular mechanisms that are involved in this process. The sporozoite encounter led to an enhanced surface expression of neutrophil CD11b suggesting a potential role of this receptor in E. bovis-mediated NETosis. Antibody-mediated blockage of CD11b confirmed this assumption and led to a significantly decreased sporozoite-triggered NET. In addition, E. bovis-induced NETosis was found to be Ca²⁺-dependent since the inhibition of store-operated calcium entry (SOCE) significantly diminished NET. Furthermore, NADPH oxidase, neutrophil elastase (NE) and myeloperoxidase (MPO) were confirmed as key molecules in sporozoite-triggered NETosis, as inhibition thereof blocked parasite-triggered NET. PMN degranulation analyses revealed a significant release of matrix metalloprotease-9 containing granules upon sporozoite exposure. We further show a significantly enhanced phosphorylation of ERK1/2 and p38 MAPK in sporozoite-exposed PMN indicating a key role of this signaling pathway in E. bovis-mediated NETosis. Accordingly, ERK 1/2 and p38 MAPK inhibition led to a significant decrease in NET formation. Finally, we demonstrate that sporozoite-induced NETosis is neither a stage-, species-, nor host-specific process.

Eimeria maxima is a common cause of coccidiosis in chickens, a disease that has a huge economic impact on poultry production. Knowledge of immunity to E. maxima and the specific mechanisms that contribute to differing levels of resistance observed between chicken breeds and between congenic lines derived from a single breed of chickens is required. This study aimed to define differences in the kinetics of the immune response of two inbred lines of White Leghorn chickens that exhibit differential resistance (line C.B12) or susceptibility (line 15I) to infection by E. maxima . Line C.B12 and 15I chickens were infected with E. maxima and transcriptome analysis of jejunal tissue was performed at 2, 4, 6 and 8 days post-infection (dpi). RNA-Seq analysis revealed differences in the rapidity and magnitude of cytokine transcription responses post-infection between the two lines. In particular, IFN-γ and IL-10 transcript expression increased in the jejunum earlier in line C.B12 (at 4 dpi) compared to line 15I (at 6 dpi). Line C.B12 chickens exhibited increases of IFNG and IL10 mRNA in the jejunum at 4 dpi, whereas in line 15I transcription was delayed but increased to a greater extent. RT-qPCR and ELISAs confirmed the results of the transcriptomic study. Higher serum IL-10 correlated strongly with higher E. maxima replication in line 15I compared to line C.B12 chickens. Overall, the findings suggest early induction of the IFN-γ and IL-10 responses, as well as immune-related genes including IL21 at 4 dpi identified by RNA-Seq, may be key to resistance to E. maxima .