Molecular characterization of serine/threonine protein phosphatase of Eimeria tenella

Impact of Eimeria tenella experimental Infection on intestinal and splenic reaction of broiler chickens

This work assesses the cell-mediated immune reaction IL-6, TNF-α, and IFN-γ of experimentally challenged broiler chicken with Eimeria tenella (E. tenella). Therefore, ninety, 2-weeks-old healthy broiler chicks were allocated as eighty chicks infected orally with 2.5 × 104 E. tenella sporulated oocysts, and the other ten birds were kept as control negative birds. Post-challenge, mortality rate, symptoms, oocysts shedding, and lesion score were evaluated. Tissue samples (cecum and spleen) were collected at 0, 4, 8, and 12 days post-infection (dpi). Ten chickens were ethically slaughtered at 0, 4, 8, and 12 days post-infection, as well as two birds from the negative control group; parts from cecal and spleen samples were kept in cryopreservation containers, and other parts were preserved in formaline 10% for further investigation. The evaluated genes (IL-6, TNF-α, and IFN-γ) were normal at 0 days and upregulated at 4 and 8 days, which reached maximum upregulation at eight dpi. The histopathological examination of the ceca and spleen were evaluated before and after challenge. It could be concluded that E. tenella revealed direct severe macroscopic and microscopic changes in cecal tissues and indirectly induced alteration in splenic tissues, resulting in upregulation of different cell mediated immune response in cecum and spleen in relation to the experimental period.

Molecular characterization of methionine aminopeptidase1 from Eimeria tenella

Coccidiosis, a serious intestinal parasitic disease caused by Eimeria spp., can result in huge annual economic losses to the poultry industry worldwide. At present, coccidiosis is mainly controlled by anticoccidial drugs. However, drug resistance has developed in Eimeria because of the long-term and unreasonable use of the drugs currently available. In our previous study, RNA-seq showed that the expression of methionine aminopeptidase1 (EtMetAP1) was up-regulated in diclazuril-resistant (DZR) and maduramicin-resistant (MRR) strains compared to drug-sensitive (DS) strain of Eimeria tenella. In this study, EtMetAP1 was cloned and expressed, and the function and characteristics of the EtMetAP1 protein were analyzed. The transcription and translation levels of EtMetAP1 in DS strain of E. tenella at different developmental stages were analyzed by qPCR and western blotting. We found that the transcription and translation levels of EtMetAP1 in second-generation merozoites (SM) were higher than those of the other three stages (unsporulated oocyst, sporulated oocyst, and sporozoites). Simultaneously, qPCR was used to analyze the mRNA transcription levels of EtMetAP1 in DS, DZR, MRR, and salinomycin-resistant (SMR) strain. The results showed that compared to the sensitive strain, the transcription levels of EtMetAP1 in DZR and MRR were up-regulated. There was no significant difference in transcription level in SMR. Indirect immunofluorescence localization showed that the protein was mainly localised in the cell membrane and cytoplasm of sporozoites and SM. An invasion inhibition test showed that anti-rEtMetAP1 polyclonal antibody could effectively inhibit the sporozoite invasion of host cells. These results suggest that the protein may be involved in the growth and development of parasites in host cells, the generation of drug resistance, and host cell invasion.

Genetic selection of Eimeria parasites in the chicken for improvement of poultry health: implications for drug resistance and live vaccine development

AbstractApicomplexan parasites of the genus Eimeria are widespread in poultry flocks and can cause the intestinal disease coccidiosis. Early studies, concerned with intraspecific variation in oocyst morphology, indicated that phenotypic changes may be induced by selection experiments conducted in vivo. Genetic selection driven by targeted selection for specific phenotypes has contributed to our understanding of the phenomenon of drug resistance and the development of live attenuated vaccines. Our present knowledge regarding genetics of Eimeria is largely based upon the utilization of such selected strains as genetic markers. Practical advantages of working with Eimeria spp. in the chicken are discussed. The selection of drug resistant strains by serial propagation has provided useful information regarding the mechanisms of drug resistance and likely longevity of anticoccidial drugs when introduced in the field. Selection experiments to develop precocious strains of Eimeria and growth in chicken embryos have contributed to the development of safe and effective live attenuated vaccines for control of coccidiosis. Establishment of protocols for genetic complementation by transient or stable transfection of Eimeria is now supporting direct manipulation of parasite genotypes, creating opportunities to expand the range and value of live parasite vaccines. Procedures for developing drug resistant and precocious lines of Eimeria and/or genetic markers described here are likely to prove useful for researchers investigating the propensity for resistance development to novel compounds and the development of new attenuated vaccines. Such investigations can be helpful in providing a better understanding of biochemical and molecular aspects of the biology of these parasites.

Identification and characterization of Eimeria tenella EtTrx1 protein

Thioredoxin (Trx) is a widespread protein regulator of redox reactions in all organisms. It operates together with NADPH and thioredoxin reductase as a general protein disulfide catalytic system. Recently, Trx has been found to be related to the process by which apicomplexan protozoa invade host cells. In this study, Eimeria tenella thioredoxin (EtTrx1) was identified and its gene structural features, expression levels at different developmental stages, localization in sporozoites, roles in adhesion and invasion, and immunogenicity were investigated. Sequence analysis indicated that EtTrx1 contains a Trx domain with a WCGPC motif in 29-33 aa and a typical Trx fold, and belongs to thioredoxin family. EtTrx1 was detected on the surface of sporozoites using anti-EtTrx1 polyclonal antibodies under non-permeabilized conditions by indirect immunofluorescence assay (IFA) and also in a secretion form. EtTrx1 protein was highly transcribed and expressed in merozoites and sporozoites by quantitative PCR and western blot. The attachment assay showed that the adherence rates of yeast cells expressing EtTrx1 on the surface to host cells were 3.1-fold higher than those of the blank control. Specific anti-EtTrx1 antibodies inhibited the invasion of sporozoites into DF-1 cells. The highest inhibition rate was up to 36.75% compared to the control group. Immunization with recombinant EtTrx1 peptides also showed significant protection against lethal infections in chickens. It could offer moderate protective efficacy (Anticoccidial Index [ACI]: 163.70), induce humoral responses, and be an effective candidate for the development of new vaccines.

Molecular characterization of glyceraldehyde-3-phosphate dehydrogenase from Eimeria tenella

Chicken coccidiosis is an extremely common and lethally epidemic disease caused by Eimeria spp. The control measures of coccidiosis depend mainly on drugs. However, the ensuing drug resistance problem has brought considerable economic loss to the poultry industry. In our previous study, comparative transcriptome analyses of a drug-sensitive (DS) strain and two drug-resistant strains (diclazuril-resistant (DZR) and maduramicin-resistant (MRR) strains) of Eimeria tenella were carried out by transcriptome sequencing. The expression of glyceraldehyde-3-phosphate dehydrogenase of E. tenella (EtGAPDH) was upregulated in the two resistant strains. In this study, we cloned and characterized EtGAPDH. Indirect immunofluorescence localization was used to observe the distribution of EtGAPDH in E. tenella. The results showed that the protein was distributed mainly on the surface of sporozoites and merozoites, and in the cytoplasm of merozoites. qPCR was performed to detect the transcription level of EtGAPDH in the different developmental stages of the E. tenella DS strain. The transcription level of EtGAPDH was significantly higher in second-generation merozoites than in the other three stages. The transcription level of EtGAPDH in the different drug-resistant strains and DS strain of E. tenella was also analyzed by qPCR. The results showed that the transcription level was significantly higher in the two drug-resistant strains (MRR and DZR) than in the DS strain. As the concentration of diclazuril and maduramicin increased, the transcription levels also increased. Western blot results showed that EtGAPDH protein was upregulated in the DZR and MRR strains. Enzyme activity showed that the enzyme activity of EtGAPDH was higher in the two resistant strains than in the DS strain. These results showed that EtGAPDH possess several roles that separate and distinct from its glycolytic function and maybe involved in the development of E. tenella resistance to anticoccidial drugs.

Exploration of the Mechanism of the Control of Coccidiosis in Chickens Based on Network Pharmacology and Molecular Docking With the Addition of Modified Gegen Qinlian Decoction

Gegen Qinlian Decoction is a long-established Chinese herbal compound for the treatment of diarrhea and dysentery, while Magnolia officinalis has been demonstrated to have some anthelmintic activity. The preliminary screening of this study showed that the addition of Modified Gegen Qinlian Decoction has some effective on the prevention and treatment of coccidiosis in chickens. However, the mechanism of its treatment of chicken coccidiosis is not clear. The network pharmacology study was based on the screening of chemical components and related targets from TCMSP and PharmMapper server databases. Genes related to chicken coccidiosis were obtained from the SRA database, and those genes that intersected with the target genes of Modified Gegen Qinlian Decoction were screened. By exploring the target interactions through the String system and enrichment analysis by the Metascape system, the mechanism of action of Modified Gegen Qinlian Decoction in chicken coccidiosis was identified. Using real-time quantitative polymerase chain reaction (RT-qPCR) to analyze the mRNA levels of the relevant factors in chicken coccidiosis, molecular docking was used to reveal the extent of binding of the key target genes predicted in the network pharmacology by the action of Modified Gegen Qinlian Decoction. Compound and target screening suggested that the 99 chemical targets of Modified Gegen Qinlian Decoction were involved in chicken coccidiosis, and the enrichment results of KEGG pathway suggested that Modified Gegen Qinlian Decoction was significantly associated with PI3K/AKT signaling pathway in chicken coccidiosis. The Hubba gene module in Cytoscape_v3.7.1 software was used to analyze the network topology to obtain the Hubba gene SRC, STAT3, and PPARG, etc. The molecular docking results showed that SRC, STAT3, and PPARG were key targets in the treatment of coccidiosis in chickens by Modified Gegen Qinlian Decoction, which was in agreement with the RT-qPCR results. Through network pharmacology, molecular docking and in vitro experiments, it was confirmed that Modified Gegen Qinlian Decoction fights against chicken coccidiosis through key targets such as SRC, STAT3, and PPARG.

Eimeria proteins: order amidst disorder

Apicomplexans are important pathogens that cause severe infections in humans and animals. The biology and pathogeneses of these parasites have shown that proteins are intrinsically modulated during developmental transitions, physiological processes and disease progression. Also, proteins are integral components of parasite structural elements and organelles. Among apicomplexan parasites, Eimeria species are an important disease aetiology for economically important animals wherein identification and characterisation of proteins have been long-winded. Nonetheless, this review seeks to give a comprehensive overview of constitutively expressed Eimeria proteins. These molecules are discussed across developmental stages, organelles and sub-cellular components vis-à-vis their biological functions. In addition, hindsight and suggestions are offered with intention to summarise the existing trend of eimerian protein characterisation and to provide a baseline for future studies.

Full-length transcriptome sequence analysis of Eimeria necatrix unsporulated oocysts and sporozoites identifies genes involved in cellular invasion

Eimeria necatrix is one of the most pathogenic chicken coccidia and causes avian coccidiosis, an enteric disease of major economic importance worldwide. Eimeria parasites have complex developmental life cycles, with an exogenous phase in the environment and an endogenous phase in the chicken intestine. Oocysts excreted by chickens rapidly undergo meiosis and cell division to form eight haploid sporozoites (SZ). SZ liberated from sporocysts in the chicken intestine migrate to their preferred site of development to initiate cellular invasion. To date, almost nothing is known about the proteins that mediate parasite invasion in E. necatrix. In order to discover genes with functions involved in cellular invasion, the transcriptome profiles of E. necatrix unsporulated oocysts (UO) and SZ were analyzed using a combination of third-generation single-molecule real-time sequencing (TGS) and second-generation sequencing (SGS) followed by qRT-PCR validation. Correction of TGS long reads by SGS short reads resulted in 34,932 (UO) and 23,040 (SZ) consensus isoforms. After subsequent assembly, a total of 4949 and 4254 genes were identified from UO and SZ libraries, respectively. A total of 8376 genes were identified as differentially expressed genes (DEGs) between SZ and UO. Compared to UO, 4057 genes were upregulated and 4319 genes were downregulated in SZ. Approximately 1399 and 1758 genes were defined as stage-specific genes in SZ and UO, respectively. Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that 2978 upregulated SZ genes were clustered into 29 GO terms, and 857 upregulated SZ genes were associated with 26 KEGG pathways. We also predicted a further 50 upregulated SZ genes and 73 upregulated UO genes encoding microneme proteins, apical membrane antigens, rhoptry neck proteins, rhoptry proteins, dense granule proteins, heat shock proteins, calcium-dependent protein kinases, cyclin-dependent kinases, cGMP-dependent protein kinase, and glycosylphosphatidylinositol-anchored surface antigens. Our data reveal new features of the E. necatrix transcriptional landscape and provide resources for the development of novel vaccine candidates against E. necatrix infection.