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1.
CABI Agric Biosci ; 2(1): 37, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34604790

RESUMEN

Coccidiosis is a potentially severe enteritis caused by species of obligate intracellular parasites of the genus Eimeria. These parasites cause significant economic losses to the poultry industry, predominantly due to compromised efficiency of production as well as the cost of control. These losses were recently estimated to cost chicken producers approximately £10.4 billion worldwide annually. High levels of Eimeria infection cause clinical coccidiosis which is a significant threat to poultry welfare, and a pre-disposing contributory factor for necrotic enteritis. Control of Eimeria parasites and coccidiosis is therefore an important endeavour; multiple approaches have been developed and these are often deployed together. This review summarises current trends in strategies for control of Eimeria, focusing on three main areas: good husbandry, chemoprophylaxis and vaccination. There is currently no "perfect solution" and there are advantages and limitations to all existing methods. Therefore, the aim of this review is to present current control strategies and suggest how these may develop in the future.

2.
Wellcome Open Res ; 6: 225, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34703904

RESUMEN

We present a genome assembly from a clonal population of Eimeria tenella Houghton parasites (Apicomplexa; Conoidasida; Eucoccidiorida; Eimeriidae). The genome sequence is 53.25 megabases in span. The entire assembly is scaffolded into 15 chromosomal pseudomolecules, with complete mitochondrion and apicoplast organellar genomes also present.

4.
Front Microbiol ; 12: 695346, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34539600

RESUMEN

Many obligate blood-sucking arthropods rely on symbiotic bacteria to provision essential B vitamins that are either missing or at sub-optimal levels in their nutritionally challenging blood diet. The poultry red mite Dermanyssus gallinae, an obligate blood-feeding ectoparasite, is a serious threat to the hen egg industry. Poultry red mite infestation has a major impact on hen health and welfare and causes a significant reduction in both egg quality and production. Thus far, the identity and biological role of nutrient provisioning bacterial mutualists from D. gallinae are little understood. Here, we demonstrate that an obligate intracellular bacterium of the Rickettsiella genus is detected in D. gallinae mites collected from 63 sites (from 15 countries) across Europe. In addition, we report the genome sequence of Rickettsiella from D. gallinae (Rickettsiella - D. gallinae endosymbiont; Rickettsiella DGE). Rickettsiella DGE has a circular 1.89Mbp genome that encodes 1,973 proteins. Phylogenetic analysis confirms the placement of Rickettsiella DGE within the Rickettsiella genus, related to a facultative endosymbiont from the pea aphid and Coxiella-like endosymbionts (CLEs) from blood feeding ticks. Analysis of the Rickettsiella DGE genome reveals that many protein-coding sequences are either pseudogenized or lost, but Rickettsiella DGE has retained several B vitamin biosynthesis pathways, suggesting the importance of these pathways in evolution of a nutritional symbiosis with D. gallinae. In silico metabolic pathway reconstruction revealed that Rickettsiella DGE is unable to synthesize protein amino acids and, therefore, amino acids are potentially provisioned by the host. In contrast, Rickettsiella DGE retains biosynthetic pathways for B vitamins: thiamine (vitamin B1) via the salvage pathway; riboflavin (vitamin B2) and pyridoxine (vitamin B6) and the cofactors: flavin adenine dinucleotide (FAD) and coenzyme A (CoA) that likely provision these nutrients to the host.

5.
PLoS Negl Trop Dis ; 15(6): e0009458, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-34077414

RESUMEN

Toxoplasma gondii parasites present strong but geographically varied signatures of population structure. Populations sampled from Europe and North America have commonly been defined by over-representation of a small number of clonal types, in contrast to greater diversity in South America. The occurrence and extent of genetic diversity in African T. gondii populations remains understudied, undermining assessments of risk and transmission. The present study was designed to establish the occurrence, genotype and phylogeny of T. gondii in meat samples collected from livestock produced for human consumption (free-range chickens, n = 173; pigs, n = 211), comparing with T. gondii detected in blood samples collected from seropositive pregnant women (n = 91) in Benue state, Nigeria. The presence of T. gondii DNA was determined using a published nested polymerase chain reaction, targeting the 529 bp multicopy gene element. Samples with the highest parasite load (assessed using quantitative PCR) were selected for PCR-restriction fragment length polymorphism (PCR-RFLP) targeting the surface antigen 3 (SAG3), SAG2 (5' and 3'), beta-tubulin (BTUB) and dense granule protein 6 (GRA6) loci, and the apicoplast genome (Apico). Toxoplasma gondii DNA was detected in all three of the populations sampled, presenting 30.6, 31.3 and 25.3% occurrence in free-range chickens, pigs and seropositive pregnant women, respectively. Quantitative-PCR indicated low parasite occurrence in most positive samples, limiting some further molecular analyses. PCR-RFLP results suggested that T. gondii circulating in the sampled populations presented with a type II genetic background, although all included a hybrid type I/II or II/III haplotype. Concatenation of aligned RFLP amplicon sequences revealed limited diversity with nine haplotypes and little indication of host species-specific or spatially distributed sub-populations. Samples collected from humans shared haplotypes with free-range chickens and/or pigs. Africa remains under-explored for T. gondii genetic diversity and this study provides the first detailed definition of haplotypes circulating in human and animal populations in Nigeria.


Asunto(s)
Enfermedades de las Aves de Corral/parasitología , Complicaciones Parasitarias del Embarazo/parasitología , Enfermedades de los Porcinos/parasitología , Toxoplasma/genética , Toxoplasmosis Animal/parasitología , Toxoplasmosis/parasitología , Adulto , Animales , Pollos , Femenino , Humanos , Nigeria/epidemiología , Enfermedades de las Aves de Corral/epidemiología , Embarazo , Complicaciones Parasitarias del Embarazo/diagnóstico , Complicaciones Parasitarias del Embarazo/epidemiología , Porcinos , Enfermedades de los Porcinos/epidemiología , Toxoplasmosis/epidemiología , Toxoplasmosis Animal/epidemiología
6.
Front Immunol ; 12: 653085, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33841436

RESUMEN

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.


Asunto(s)
Pollos/inmunología , Coccidiosis/veterinaria , Susceptibilidad a Enfermedades/inmunología , Eimeria/inmunología , Enfermedades de las Aves de Corral/inmunología , Animales , Pollos/parasitología , Coccidiosis/inmunología , Coccidiosis/parasitología , Coccidiosis/patología , Regulación de la Expresión Génica/inmunología , Interferón gamma/genética , Interleucina-10/genética , Interleucinas/genética , Yeyuno/inmunología , Yeyuno/parasitología , Yeyuno/patología , Enfermedades de las Aves de Corral/parasitología , Enfermedades de las Aves de Corral/patología , RNA-Seq
7.
Avian Pathol ; : 1-5, 2021 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-33823695

RESUMEN

Coccidiosis, caused by Eimeria species parasites, remains a major threat to poultry production, undermining economic performance and compromising welfare. The recent characterization of three new Eimeria species that infect chickens has highlighted that many gaps remain in our knowledge of the biology and epidemiology of these parasites. Concerns about the use of anticoccidial drugs, widespread parasite drug resistance, the need for vaccines that can be used across broiler as well as layer and breeder sectors, and consumer preferences for "clean" farming, all point to the need for novel control strategies. New research tools including vaccine delivery vectors, high throughput sequencing, parasite transgenesis and sensitive molecular assays that can accurately assess parasite development in vitro and in vivo are all proving helpful in the ongoing quest for improved cost-effective, scalable strategies for future control of coccidiosis.

8.
Int J Parasitol ; 51(8): 621-634, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-33713650

RESUMEN

More than 68 billion chickens were produced globally in 2018, emphasising their major contribution to the production of protein for human consumption and the importance of their pathogens. Protozoan Eimeria spp. are the most economically significant parasites of chickens, incurring global costs of more than UK £10.4 billion per annum. Seven Eimeria spp. have long been recognised to infect chickens, with three additional cryptic operational taxonomic units (OTUs) first described more than 10 years ago. As the world's farmers attempt to reduce reliance on routine use of antimicrobials in livestock production, replacing drugs that target a wide range of microbes with precise species- and sometimes strain-specific vaccines, the breakthrough of cryptic genetic types can pose serious problems. Consideration of biological characteristics including oocyst morphology, pathology caused during infection and pre-patent periods, combined with gene-coding sequences predicted from draft genome sequence assemblies, suggest that all three of these cryptic Eimeria OTUs possess sufficient genetic and biological diversity to be considered as new and distinct species. The ability of these OTUs to compromise chicken bodyweight gain and escape immunity induced by current commercially available anticoccidial vaccines indicates that they could pose a notable threat to chicken health, welfare, and productivity. We suggest the names Eimeria lata n. sp., Eimeria nagambie n. sp. and Eimeria zaria n. sp. for OTUs x, y and z, respectively, reflecting their appearance (x) or the origins of the first isolates of these novel species (y, z).


Asunto(s)
Coccidiosis , Eimeria , Enfermedades de las Aves de Corral , Vacunas Antiprotozoos , Animales , Pollos , Coccidiosis/prevención & control , Coccidiosis/veterinaria , Eimeria/genética , Humanos , Nigeria , Enfermedades de las Aves de Corral/prevención & control
9.
Front Vet Sci ; 8: 640041, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33693044

RESUMEN

Eimeria species parasites infect the gastrointestinal tract of chickens, causing disease and impacting on production. The poultry industry relies on anticoccidial drugs and live vaccines to control Eimeria and there is a need for novel, scalable alternatives. Understanding the outcomes of experimental infection in commercial chickens is valuable for assessment of novel interventions. We examined the impact of different infectious doses of Eimeria tenella (one low dose, three high doses) in three commercial layer chicken lines, evaluating lesion score, parasite replication and cytokine response in the caeca. Groups of eight to ten chickens were housed together and infected with 250, 4,000, 8,000 or 12,000 sporulated oocysts at 21 days of age. Five days post-infection caeca were assessed for lesions and to quantify parasite replication by qPCR and cytokine transcription by RT-qPCR. Comparison of the three high doses revealed no significant variation between them in observed lesions or parasite replication with all being significantly higher than the low dose infection. Transcription of IFN-γ and IL-10 increased in all infected chickens relative to unchallenged controls, with no significant differences associated with dose magnitude (p > 0.05). No significant differences were detected in lesion score, parasite replication or caecal cytokine expression between the three lines of chickens. We therefore propose 4,000 E. tenella oocysts is a sufficient dose to reliably induce lesions in commercial layer chickens, and that estimates of parasite replication can be derived by qPCR from these same birds. However, more accurate quantification of Eimeria replication requires a separate low dose challenge group. Optimisation of challenge dose in an appropriate chicken line is essential to maximize the value of in vivo efficacy studies. For coccidiosis, this approach can reduce the numbers of chickens required for statistically significant studies and reduce experimental severity.

10.
Commun Biol ; 4(1): 376, 2021 03 19.
Artículo en Inglés | MEDLINE | ID: mdl-33742128

RESUMEN

In infections by apicomplexan parasites including Plasmodium, Toxoplasma gondii, and Eimeria, host interactions are mediated by proteins including families of membrane-anchored cysteine-rich surface antigens (SAGs) and SAG-related sequences (SRS). Eimeria tenella causes caecal coccidiosis in chickens and has a SAG family with over 80 members making up 1% of the proteome. We have solved the structure of a representative E. tenella SAG, EtSAG19, revealing that, despite a low level of sequence similarity, the entire Eimeria SAG family is unified by its three-layer αßα fold which is related to that of the CAP superfamily. Furthermore, sequence comparisons show that the Eimeria SAG fold is conserved in surface antigens of the human coccidial parasite Cyclospora cayetanensis but this fold is unrelated to that of the SAGs/SRS proteins expressed in other apicomplexans including Plasmodium species and the cyst-forming coccidia Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti. However, despite having very different structures, Consurf analysis showed that Eimeria SAG and Toxoplasma SRS families each exhibit marked hotspots of sequence hypervariability that map to their surfaces distal to the membrane anchor. This suggests that the primary and convergent purpose of the different structures is to provide a platform onto which sequence variability can be imposed.


Asunto(s)
Antígenos de Protozoos/metabolismo , Eimeria tenella/metabolismo , Proteínas Protozoarias/metabolismo , Antígenos de Protozoos/química , Antígenos de Protozoos/genética , Cristalografía por Rayos X , Eimeria tenella/genética , Evolución Molecular , Variación Genética , Modelos Moleculares , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Pliegue de Proteína , Proteínas Protozoarias/química , Proteínas Protozoarias/genética , Relación Estructura-Actividad
11.
Parasitology ; 148(5): 623-629, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33541446

RESUMEN

Coccidiosis caused by Eimeria species is a well-recognized disease of livestock. Enteric Eimeria infections are common, but disease usually only manifests when infection intensity is abnormally high. Campylobacter species are important zoonotic enteric bacterial pathogens for which livestock are important reservoir hosts. The diversity and epidemiology of ovine Eimeria and Campylobacter infections on two farms in north-western England were explored through a 24-month survey of shedding in sheep feces. Most animals were infected with at least one of 10 different Eimeria species, among which E. bakuensis and E. ovinoidalis were most common. An animal's age and the season of sampling were associated with the probability and intensity of Eimeria infection. Season of sampling was also associated with the probability of Campylobacter infection. Interestingly, higher intensities of Eimeria infections were significantly more common in animals not co-infected with Campylobacter. We explored the determinants of E. bakuensis and E. ovinoidalis infections, observing that being infected with either significantly increased the likelihood of infection with the other. The prevalence of E. ovinoidalis infections was significantly lower in sheep infected with Campylobacter. Recognition that co-infectors shape the dynamics of parasite infection is relevant to the design of effective infection control programmes.


Asunto(s)
Infecciones por Campylobacter/veterinaria , Campylobacter/fisiología , Coccidiosis/veterinaria , Coinfección/veterinaria , Eimeria/fisiología , Enfermedades de las Ovejas/epidemiología , Animales , Infecciones por Campylobacter/epidemiología , Infecciones por Campylobacter/microbiología , Coccidiosis/epidemiología , Coccidiosis/parasitología , Coinfección/epidemiología , Coinfección/microbiología , Coinfección/parasitología , Inglaterra/epidemiología , Ovinos , Enfermedades de las Ovejas/microbiología , Enfermedades de las Ovejas/parasitología , Oveja Doméstica
12.
Avian Pathol ; 50(1): 1, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33287560
13.
Front Vet Sci ; 7: 558182, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33251254

RESUMEN

Ionophore compounds active against Eimeria species are widely used in intensive broiler systems and have formed the backbone of coccidiosis control for almost 50 years. Producers, however, are under pressure to reduce ionophore use due to consumer concerns over antimicrobial usage in food animals, and antimicrobial resistance. Moreover, current vaccines against Eimeria are commonly considered to be less cost-effective in intensive broiler systems, especially in Europe where attenuated live vaccines are used. An economic assessment of the impact of Eimeria and the disease coccidiosis, including the cost implications of different efficacies of control, is therefore timely to provide evidence for industry and policy development. A mechanistic model of broiler production under varying infection and control states was used to construct a dataset from which system productivity can be measured. Coccidiosis impact increased rapidly as control efficacy decreased. In the total absence of control, median impact was found to maximize at between €2.55 and €2.97 in lost production per meter squared of broiler house over a 33 day growing period. Coccidiosis remains a major risk to intensive broiler systems and the model developed allows investigation of issues related to coccidiosis control, antimicrobial use and the development of antimicrobial resistance.

14.
Onderstepoort J Vet Res ; 87(1): e1-e10, 2020 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-33054259

RESUMEN

This study was conducted from January to October 2018 with the objective to determine the prevalence and genetic diversity of Eimeria species in broiler and free-range chickens in KwaZulu-Natal province, South Africa. A total of 342 faecal samples were collected from 12 randomly selected healthy broiler chicken farms and 40 free-range chickens from 10 different locations. Faecal samples were screened for the presence of Eimeria oocysts using a standard flotation method. The species of Eimeria isolates were confirmed by amplification of the internal transcribed spacer 1 (ITS-1) partial region and sequences analysis. Among broiler and free-ranging chickens, 19 out of 41 pens (46.3%) and 25 out of 42 faecal samples (59.5%) were positive for Eimeria infection. Molecular detection revealed the following species: Eimeria maxima, Eimeria tenella, Eimeria acervulina, Eimeria brunetti and Eimeria mitis in all the samples screened. Similarly, polymerase chain reaction assays specific for three cryptic Eimeria operational taxonomic units were negative for all the samples. Phylogenetic analysis of the ITS-1 sequences supported species identity with the greatest variation detected for E. mitis. This study provides information on the range and identity of Eimeria species, and their genetic relatedness, circulating in commercially reared broilers and free-ranging chickens from different locations in KwaZulu-Natal province.


Asunto(s)
Pollos , Coccidiosis/veterinaria , Eimeria/fisiología , Variación Genética , Enfermedades de las Aves de Corral/epidemiología , Animales , Coccidiosis/epidemiología , Coccidiosis/parasitología , Eimeria/clasificación , Eimeria/genética , Eimeria/aislamiento & purificación , Heces/parasitología , Oocistos/aislamiento & purificación , Filogenia , Enfermedades de las Aves de Corral/parasitología , Prevalencia , Sudáfrica/epidemiología
15.
Genes (Basel) ; 11(9)2020 09 21.
Artículo en Inglés | MEDLINE | ID: mdl-32967167

RESUMEN

Eimeria, protozoan parasites from the phylum Apicomplexa, can cause the enteric disease coccidiosis in all farmed animals. Coccidiosis is commonly considered to be most significant in poultry; due in part to the vast number of chickens produced in the World each year, their short generation time, and the narrow profit margins associated with their production. Control of Eimeria has long been dominated by routine chemoprophylaxis, but has been supplemented or replaced by live parasite vaccination in a minority of production sectors. However, public and legislative demands for reduced drug use in food production is now driving dramatic change, replacing reliance on relatively indiscriminate anticoccidial drugs with vaccines that are Eimeria species-, and in some examples, strain-specific. Unfortunately, the consequences of deleterious selection on Eimeria population structure and genome evolution incurred by exposure to anticoccidial drugs or vaccines are unclear. Genome sequence assemblies were published in 2014 for all seven Eimeria species that infect chickens, stimulating the first population genetics studies for these economically important parasites. Here, we review current knowledge of eimerian genomes and highlight challenges posed by the discovery of new, genetically cryptic Eimeria operational taxonomic units (OTUs) circulating in chicken populations. As sequencing technologies evolve understanding of eimerian genomes will improve, with notable utility for studies of Eimeria biology, diversity and opportunities for control.


Asunto(s)
Eimeria/genética , Genoma de Protozoos/genética , Animales , Biología/métodos , Pollos/parasitología , Coccidiosis/tratamiento farmacológico , Coccidiosis/parasitología , Coccidiostáticos/farmacología , Eimeria/efectos de los fármacos , Filogenia , Enfermedades de las Aves de Corral/parasitología
16.
Vet Res ; 51(1): 115, 2020 Sep 14.
Artículo en Inglés | MEDLINE | ID: mdl-32928271

RESUMEN

Coccidiosis, caused by Eimeria species parasites, has long been recognised as an economically significant disease of chickens. As the global chicken population continues to grow, and its contribution to food security intensifies, it is increasingly important to assess the impact of diseases that compromise chicken productivity and welfare. In 1999, Williams published one of the most comprehensive estimates for the cost of coccidiosis in chickens, featuring a compartmentalised model for the costs of prophylaxis, treatment and losses, indicating a total cost in excess of £38 million in the United Kingdom (UK) in 1995. In the 25 years since this analysis the global chicken population has doubled and systems of chicken meat and egg production have advanced through improved nutrition, husbandry and selective breeding of chickens, and wider use of anticoccidial vaccines. Using data from industry representatives including veterinarians, farmers, production and health experts, we have updated the Williams model and estimate that coccidiosis in chickens cost the UK £99.2 million in 2016 (range £73.0-£125.5 million). Applying the model to data from Brazil, Egypt, Guatemala, India, New Zealand, Nigeria and the United States resulted in estimates that, when extrapolated by geographical region, indicate a global cost of ~ £10.4 billion at 2016 prices (£7.7-£13.0 billion), equivalent to £0.16/chicken produced. Understanding the economic costs of livestock diseases can be advantageous, providing baselines to evaluate the impact of different husbandry systems and interventions. The updated cost of coccidiosis in chickens will inform debates on the value of chemoprophylaxis and development of novel anticoccidial vaccines.


Asunto(s)
Crianza de Animales Domésticos/economía , Pollos , Coccidiosis/veterinaria , Enfermedades de las Aves de Corral/economía , Animales , Coccidiosis/economía
17.
Front Vet Sci ; 7: 553, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32974406

RESUMEN

The poultry red mite (Dermanyssus gallinae), an obligatory blood feeding ectoparasite, is primarily associated with laying hens where it is estimated to cause losses of ~€231 million per annum to European farmers. Moderate to high infestation levels result in negative impacts on hen welfare, including increased cannibalism, irritation, feather pecking, restlessness, anemia, and mortality. Acaricides are currently the prevailing method of population control for D. gallinae, although resistance against some classes of acaricide has been widely reported. The development of resistance highlights a growing need for research into alternative control methods, including the development of a suitable and effective vaccine. Understanding the genetic structure of D. gallinae populations can support improved management of acaricide resistance and sustainability of future vaccines, but limited data are currently available. The aim of this study was to characterize D. gallinae isolates from Europe, targeting the cytochrome c oxidase subunit 1 (COI) gene to gain an insight into population structure and genetic diversity of currently circulating mites. Dermanyssus gallinae isolates were collected from Albania, Belgium, Croatia, Czech Republic, Denmark, France, Greece, Italy, the Netherlands, Portugal, Romania, Slovenia, Turkey and the United Kingdom. Genomic DNA was extracted from individual adult D. gallinae mites and a 681bp fragment of the COI gene was amplified and sequenced. Phylogenetic analyses of 195 COI sequences confirmed the presence of multiple lineages across Europe with 76 distinct haplotypes split across three main haplogroups and six sub-haplogroups. Importantly there is considerable inter- and intra-country variation across Europe, which could result from the movement of poultry or transfer of contaminated equipment and/or materials and husbandry practices.

18.
Front Vet Sci ; 7: 420, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32851011

RESUMEN

This study investigated the in vitro effects of Greek oregano and garlic essential oils on inhibition of Eimeria parasites and their in vivo effects on production performance, intestinal bacteria counts, and oocyst output. An inhibition assay was performed in vitro using Eimeria tenella Wisconsin strain sporozoites and Madin-Darby bovine kidney (MDBK) cells. Intracellular sporozoite invasion was quantified by detection of E. tenella DNA using qPCR from cell monolayers harvested at 2 and 24 h post-infection. Parasite invasion was inhibited by the oregano essential oil at the concentration of 100 µg/ml by 83 or 93% after 2 or 24 h, respectively. Garlic essential oil reached a maximum inhibition of 70% after 24 h with the 50 µg/ml concentration. Normal morphology was observed in MDBK cells exposed to concentrations of 100 µl/ml of garlic or oregano for over 24 h. In the in vivo trial, 180 male broiler chicks (45.3 ± 0.7 g) were allocated into two treatments (6 pens of 15 chicks per treatment). Control treatment was fed commercial diets without antibiotics or anticoccidials. The ORE-GAR treatment was fed the same control diets, further supplemented with a premix (1 g/kg feed) containing the oregano (50 g/kg premix) and garlic (5 g/kg premix) essential oils. At day 37, all birds were slaughtered under commercial conditions, and intestinal samples were collected. ORE-GAR treatment had improved final body weight (1833.9 vs. 1.685.9 g; p < 0.01), improved feed conversion ratio (1.489 vs. 1.569; p < 0.01), and reduced fecal oocyst excretion (day 28: 3.672 vs. 3.989 log oocysts/g, p < 0.01; day 37: 3.475 vs. 4.007 log oocysts/g, p < 0.001). In the caecal digesta, ORE-GAR treatment had lower total anaerobe counts (8.216 vs. 8.824 CFU/g; p < 0.01), whereas in the jejunum digesta the ORE-GAR treatment had higher counts of E. coli (5.030 vs. 3.530 CFU/g; p = 0.01) and Enterobacteriaceae (5.341 vs. 3.829 CFU/g; p < 0.01), and lower counts of Clostridium perfringens (2.555 vs. 2.882 CFU/g; p < 0.01). In conclusion, the combined supplementation of oregano and garlic essential oils had a potent anticoccidial effect in vitro and a growth-promoting effect in broilers reared in the absence of anticoccidial drugs.

19.
Parasit Vectors ; 13(1): 343, 2020 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-32650837

RESUMEN

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 (EmAMA1 and EmIMP1) 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 EmAMA1 and EmIMP1 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 EmAMA1, or admixtures of E. tenella expressing EmAMA1 or EmIMP1, 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.


Asunto(s)
Pollos/parasitología , Coccidiosis/veterinaria , Eimeria tenella , Vacunas Antiprotozoos , Animales , Antígenos de Protozoos/inmunología , Peso Corporal/efectos de los fármacos , Pollos/inmunología , Coccidiosis/prevención & control , Coccidiosis/terapia , Eimeria/efectos de los fármacos , Eimeria/crecimiento & desarrollo , Eimeria/inmunología , Eimeria tenella/efectos de los fármacos , Eimeria tenella/crecimiento & desarrollo , Eimeria tenella/inmunología , Genes Protozoarios/inmunología , Interferón gamma/efectos de los fármacos , Interleucina-10/metabolismo , Enfermedades de las Aves de Corral/parasitología , Enfermedades de las Aves de Corral/prevención & control , Vacunas Antiprotozoos/biosíntesis , Vacunas Antiprotozoos/uso terapéutico , Transfección , Transgenes/inmunología , Vacunación/métodos , Vacunación/veterinaria , Vacunas Atenuadas/biosíntesis , Vacunas Atenuadas/uso terapéutico
20.
Front Vet Sci ; 7: 101, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32175341

RESUMEN

Eimeria infection impacts upon chicken welfare and economic productivity of the poultry sector. Live coccidiosis vaccines for chickens have been available for almost 70 years, but the requirement to formulate blends of oocysts from multiple Eimeria species makes vaccine production costly and logistically demanding. A multivalent vaccine that does not require chickens for its production and can induce protection against multiple Eimeria species is highly desirable. However, despite the identification and testing of many vaccine candidate antigens, no recombinant coccidiosis vaccine has been developed commercially. Currently, assessment of vaccine efficacy against Eimeria, and the disease coccidiosis, can be done only through in vivo vaccination and challenge experiments but the design of such studies has been highly variable. Lack of a "standard" protocol for assessing vaccine efficacy makes comparative evaluations very difficult, complicating vaccine development, and validation. The formulation and schedule of vaccination, the breed of chicken and choice of husbandry system, the species, strain, magnitude, and timing of delivery of the parasite challenge, and the parameters used to assess vaccine efficacy all influence the outcomes of experimental trials. In natural Eimeria infections, the induction of strong cell mediated immune responses are central to the development of protective immunity against coccidiosis. Antibodies are generally regarded to be of lesser importance. Unfortunately, there are no specific immunological assays that can accurately predict how well a vaccine will protect against coccidiosis (i.e., no "correlates of protection"). Thus, experimental vaccine studies rely on assessing a variety of post-challenge parameters, including assessment of pathognomonic lesions, measurements of parasite replication such as oocyst output or quantification of Eimeria genomes, and/or measurements of productivity such as body weight gain and feed conversion rates. Understanding immune responses to primary and secondary infection can inform on the most appropriate immunological assays. The discovery of new antigens for different Eimeria species and the development of new methods of vaccine antigen delivery necessitates a more considered approach to assessment of novel vaccines with robust, repeatable study design. Careful consideration of performance and welfare factors that are genuinely relevant to chicken producers and vaccine manufacturers is essential.

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