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Parasitology Mar 2016Neospora caninum is a leading cause of abortion in cattle, and is thus an important veterinary health problem of high economic significance. Vaccination has been... (Review)
Review
Neospora caninum is a leading cause of abortion in cattle, and is thus an important veterinary health problem of high economic significance. Vaccination has been considered a viable strategy to prevent bovine neosporosis. Different approaches have been investigated, and to date the most promising results have been achieved with live-attenuated vaccines. Subunit vaccines have also been studied, and most of them represented components that are functionally involved in (i) the physical interaction between the parasite and its host cell during invasion or (ii) tachyzoite-to-bradyzoite stage conversion. Drugs have been considered as an option to limit the effects of vertical transmission of N. caninum. Promising results with a small panel of compounds in small laboratory animal models indicate the potential value of a chemotherapeutical approach for the prevention of neosporosis in ruminants. For both, vaccines and drugs, the key for success in preventing vertical transmission lies in the application of bioactive compounds that limit parasite proliferation and dissemination, without endangering the developing fetus not only during an exogenous acute infection but also during recrudescence of a chronic infection. In this review, the current status of vaccine and drug development is presented and novel strategies against neosporosis are discussed.
Topics: Animals; Cattle; Cattle Diseases; Coccidiosis; Disease Models, Animal; Infectious Disease Transmission, Vertical; Mice; Neospora; Protozoan Vaccines; Sheep; Sheep Diseases; Vaccination
PubMed: 26626124
DOI: 10.1017/S0031182015001596 -
International Journal of Antimicrobial... Mar 2018Coccidiosis is a self-limiting disease that is universally present in poultry operations, causing extensive damage to the intestinal lining of the bird. Global economic... (Review)
Review
Coccidiosis is a self-limiting disease that is universally present in poultry operations, causing extensive damage to the intestinal lining of the bird. Global economic losses from coccidiosis are estimated to be $3 billion per year. In-feed anticoccidial use has been the predominant form of coccidiosis control. However, due to widespread emergence of antimicrobial resistance, concerns have been raised regarding the safety of anticoccidials and the potential impact on human, animal, and environmental health. To investigate the benefits, risks, and alternatives to anticoccidial use, a comprehensive review of recent literature was conducted. Several live vaccines are available, which, when used in combination with anticoccidials, have been shown to help restore sensitivity of infective parasites. However, their use has been limited because of increased cost; increased susceptibility to bacterial enteritis; challenges with consistent application; and slow development of immunity. Various alternative feed products are available, but do not have a direct anticoccidial effect, and few studies have demonstrated consistent field efficacy of these products. Consumer and environmental safety of anticoccidials is monitored and assessed by governing bodies. Furthermore, there is a lack of current evidence to indicate that bacterial resistance poses a public health concern. The findings from this review indicate that in the absence of alternatives, poultry production is optimized by using anticoccidials, benefiting all three pillars of sustainability, including social (bird health, welfare, and food safety), economic (production efficiency), and environmental aspects.
Topics: Animal Husbandry; Animals; Coccidiosis; Coccidiostats; Poultry; Poultry Diseases; Protozoan Vaccines
PubMed: 28935212
DOI: 10.1016/j.ijantimicag.2017.09.004 -
Infection, Genetics and Evolution :... Oct 2020Neospora caninum is a cyst-forming coccidian parasite of veterinary and economical significance, affecting dairy and beef cattle industries on a global scale.... (Review)
Review
Neospora caninum is a cyst-forming coccidian parasite of veterinary and economical significance, affecting dairy and beef cattle industries on a global scale. Comparative studies suggest that N. caninum consists of a globally dispersed, diverse population of lineages, distinguished by their geographical origin, broad host range, and phenotypic features. This viewpoint is however changing. While intraspecies diversity, and more specifically pathogenic variability, has been experimentally demonstrated in a myriad of studies, the underlying contributors and sources responsible for such diversity have remained nebulous. However, recent large-scale sequence and bioinformatics studies have aided in revealing intrinsic genetic differences distinguishing isolates of this species, that await further characterisation as causative links to virulence and pathogenicity. Furthermore, progress on N. caninum research as a non-model organism is hindered by a lack of robust, annotated genomic, transcriptomic, and proteomic data for the species, especially compared to other thoroughly studied Apicomplexa such as Toxoplasma gondii and Plasmodium species. This review explores the current body of knowledge on intra-species diversity within N. caninum. This includes the contribution of sequence variants in both coding and non-coding regions, the presence of genome polymorphic hotspots, and the identification of non-synonymous mutations. The implications of such diversity on important parasite phenotypes such as pathogenicity and population structure are also discussed. Lastly, the identification of potential virulence factors from both in-silico and next generation sequencing studies is examined, offering new insights into potential avenues for future research on neosporosis.
Topics: Biological Evolution; Genetic Markers; Genetic Variation; Genome, Protozoan; Neospora; Protozoan Vaccines
PubMed: 32619639
DOI: 10.1016/j.meegid.2020.104444 -
Parasitology Research Jun 2017Toxoplasmosis is an infectious disease caused by the intracellular parasite Toxoplasma gondii that affects about one third of the world's population. The diagnosis of... (Review)
Review
Toxoplasmosis is an infectious disease caused by the intracellular parasite Toxoplasma gondii that affects about one third of the world's population. The diagnosis of this disease is carried out by parasite isolation and host antibodies detection. However, the diagnosis presents problems in regard to test sensitivity and specificity. Currently, the most effective T. gondii treatment is a combination of pyrimethamine and sulfadiazine, although both drugs are toxic to the host. In addition to the problems that compromise the effective diagnosis and treatment of toxoplasmosis, there are no reports or indications of any vaccine capable of fully protecting against this infection. Nanomaterials, smaller than 1000 nm, are currently being investigated as an alternative tool in the management of T. gondii infection. This article reviews how recent nanotechnology advances indicate the utility of nanomaterials in toxoplasmosis diagnosis, treatment, and vaccine development.
Topics: Animals; Humans; Nanostructures; Protozoan Vaccines; Toxoplasma; Toxoplasmosis
PubMed: 28477099
DOI: 10.1007/s00436-017-5458-2 -
Advances in Parasitology 2024Neospora caninum is an apicomplexan and obligatory intracellular parasite, which is the leading cause of reproductive failure in cattle and affects other farm and... (Review)
Review
Neospora caninum is an apicomplexan and obligatory intracellular parasite, which is the leading cause of reproductive failure in cattle and affects other farm and domestic animals, but also induces neuromuscular disease in dogs of all ages. In cattle, neosporosis is an important health problem, and has a considerable economic impact. To date there is no protective vaccine or chemotherapeutic treatment on the market. Immuno-prophylaxis has long been considered as the best control measure. Proteins involved in host cell interaction and invasion, as well as antigens mediating inflammatory responses have been the most frequently assessed vaccine targets. However, despite considerable efforts no effective vaccine has been introduced to the market to date. The development of effective compounds to limit the effects of vertical transmission of N. caninum tachyzoites has emerged as an alternative or addition to vaccination, provided suitable targets and safe and efficacious drugs can be identified. Additionally, the combination of both treatment strategies might be interesting to further increase protectivity against N. caninum infections and to decrease the duration of treatment and the risk of potential drug resistance. Well-established and standardized animal infection models are key factors for the evaluation of promising vaccine and compound candidates. The vast majority of experimental animal experiments concerning neosporosis have been performed in mice, although in recent years the numbers of experimental studies in cattle and sheep have increased. In this review, we discuss the recent findings concerning the progress in drug and vaccine development against N. caninum infections in mice and ruminants.
Topics: Animals; Coccidiosis; Neospora; Protozoan Vaccines; Cattle; Cattle Diseases; Vaccine Development
PubMed: 38754928
DOI: 10.1016/bs.apar.2024.01.001 -
Parasitology Research Oct 2022Chicken coccidiosis is an economically significant disease of commercial chicken industry accounting for losses of more than £10.4 billion (according to 2016 prices).... (Review)
Review
Chicken coccidiosis is an economically significant disease of commercial chicken industry accounting for losses of more than £10.4 billion (according to 2016 prices). Additionally, the costs incurred in prophylaxis and therapeutics against chicken coccidiosis in developing countries (for instance Pakistan according to 2018 prices) reached US $45,000.00 while production losses for various categories of chicken ranges 104.74 to US $2,750,779.00. The infection has been reported from all types of commercial chickens (broiler, layer, breeder) having a range of reported prevalence of 7-90%. The concern of resistance towards major anticoccidials has provided a way forward to vaccine research and development. For prophylaxis of chicken coccidiosis, live virulent, attenuated, ionophore tolerant strains and recombinant vaccines have been extensively trialed and commercialized. Eimeria antigens and novel vaccine adjuvants have elicited the protective efficacy against coccidial challenge. The cost of production and achieving robust immune responses in birds are major challenges for commercial vaccine production. In the future, research should be focused on the development of multivalent anticoccidial vaccines for commercial poultry. Efforts should also be made on the discovery of novel antigens for incorporation into vaccine designs which might be more effective against multiple Eimeria species. This review presents a recap to the overall progress against chicken Eimeria with particular reference to previous decade. The article presents critical analysis of potential areas for future research in chicken Eimeria vaccine development.
Topics: Animals; Antigens; Chickens; Coccidiosis; Eimeria; Poultry Diseases; Protozoan Vaccines
PubMed: 35925452
DOI: 10.1007/s00436-022-07612-6 -
Parasitology Research Jan 2022Coccidiosis is an intestinal parasitic disease that causes huge economic losses to the poultry industry globally. Eimeria tenella belonging to protozoon is the causative...
Coccidiosis is an intestinal parasitic disease that causes huge economic losses to the poultry industry globally. Eimeria tenella belonging to protozoon is the causative agent of cecal coccidiosis in chicken, and it causes enormous damage to poultry industry. The surface antigens (SAGs) of apicomplexan parasites have functions of attachment and invasion in host-parasite interaction. As a result of parasitic invasion, host immune response is triggered. However, the immunogenicity and potency of E. tenella surface antigen 6 and 15 (EtSAG 6 and 15), as vaccinal candidate antigen, remain largely unknown. Therefore, gene fragments of E. tenella EtSAG 6 and 15 were amplified and transformed to pET28a prokaryotic vector for recombinant protein expression. The pEGFP-N1 eukaryotic vectors with EtSAG 6 and 15 amplification fragments (pEGFP-N1-EtSAG 5 and 16) were transformed into 293 T cell line. The results of reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis revealed successful expressions of EtSAG 6 and 15 in Escherichia coli and 293 T cells. Subsequently, animal experiments of 49 cobb broilers were performed to evaluate immunoprotection of recombinant proteins and DNA vaccines derived from E. tenella EtSAG 5 and 16 with an immunizing dose of 100 μg, respectively. Chickens vaccinated with rEtSAG 6 protein, rEtSAG 15 protein, pEGFP-N1-EtSAG 6 plasmid, or pEGFP-N1-EtSAG 15 plasmid showed no significant increase in IFN-γor interleukin-4 (IL-4) level compared with control groups. Chickens vaccinated with protein rEtSAG 6, protein rEtSAG 15, pEGFP-N1-EtSAG 6 plasmid, or pEGFP-N1-EtSAG 15 exhibited higher weight gains, lower oocyst output, and lower mean lesion scores, compared with infection control group. Among the four immunized groups, plasmid EGFP-N1-EtSAG 6 (100 μg) group exhibited the highest anticoccidial index (ACI) value (150.20). Overall, plasmids EGFP-N1-EtSAG 6 and 15, as DNA vaccines, provided a more effective immunoprotection for chickens against E. tenella than protein rEtSAG 6 and protein rEtSAG 15 as subunit vaccines. EtSAG 6 and 15 are promising candidate antigen genes for developing coccidiosis vaccine.
Topics: Animals; Antigens, Surface; Chickens; Eimeria tenella; Poultry Diseases; Protozoan Vaccines; Recombinant Proteins; Vaccines, DNA
PubMed: 34816300
DOI: 10.1007/s00436-021-07364-9 -
Poultry Science Feb 2019Coccidiosis is an economically significant enteric disease caused by Eimeria species. Control of the disease is achieved through various means, including chemical... (Comparative Study)
Comparative Study
Coccidiosis is an economically significant enteric disease caused by Eimeria species. Control of the disease is achieved through various means, including chemical anticoccidial drugs, ionophore antibiotics, and vaccination. Differences between the vaccines include the number of oocysts per dose (varying by as much as tenfold between vaccines), attenuation status of the oocysts, and the species present within the vaccine. Coccidia vaccines are typically administered via spray cabinet to day old chicks; however, a new gel-based delivery system that claims to elongate preening time and increase oocyst ingestion has been introduced and is specifically recommended for certain low dose vaccines. The purpose of this trial was to compare the application properties between high and low oocyst dose vaccines administered via gel and spray delivery systems to determine if application systems could potentially affect application success. The vaccines were mixed into gel and spray diluents per manufacturer's instructions, and samples were taken to assess how well the oocysts remained in suspension. Gel and spray application patterns were assessed by measuring the size and number of droplets applied onto a plexiglass sheet in a chick basket. Different size droplets were collected and oocyst enumeration and speciation were performed. Results show that no settling occurred after mixing in either diluent. As expected, the number of oocysts per droplet increased as droplet size of the spray administration increased but stayed constant in the uniform droplet size of gel administration. There was also a consistent number of oocysts found in each of the sections across the plexiglass sheet. Taken together, these data will aid poultry producers in deciding which delivery system will provide the best application in their production system.
Topics: Animals; Chickens; Coccidiosis; Eimeria; Oocysts; Poultry Diseases; Protozoan Vaccines; Vaccination; Vaccines, Attenuated
PubMed: 30376126
DOI: 10.3382/ps/pey364 -
Parasitology Research Jun 2019Coccidiosis is a major poultry disease which compromises animal welfare and costs the global chicken industry a huge economic loss. As a result, research entailing... (Review)
Review
Coccidiosis is a major poultry disease which compromises animal welfare and costs the global chicken industry a huge economic loss. As a result, research entailing coccidial control measures is crucial. Coccidiosis is caused by Eimeria parasites that are highly immunogenic. Consequently, a low dosage of the Eimeria parasite supplied by a vaccine will enable the host organism to develop an innate immune response towards the pathogen. The production of traditional live anticoccidial vaccines is limited by their low reproductive index and high production costs, among other factors. Recombinant vaccines overcome these limitations by eliciting undesired contaminants and prevent the reversal of toxoids back to their original toxigenic form. Recombinant vaccines are produced using defined Eimeria antigens and harmless adjuvants. Thus, studies regarding the identification of potent novel Eimeria antigens which stimulate both cell-mediated and humoral immune responses in chickens are essential. Although the prevalence and risk posed by Eimeria have been well established, there is a dearth of information on genetic and antigenic diversity within the field. Therefore, this paper discusses the potential and efficiency of recombinant vaccines as an anticoccidial control measure. Novel protective Eimeria antigens and their antigenic diversity for the production of cheap, easily accessible recombinant vaccines are also reviewed.
Topics: Adjuvants, Immunologic; Animals; Antigens; Chickens; Coccidiosis; Eimeria; Poultry Diseases; Protozoan Vaccines
PubMed: 31065831
DOI: 10.1007/s00436-019-06338-2 -
Mind the gaps in research on the control of gastrointestinal nematodes of farmed ruminants and pigs.Transboundary and Emerging Diseases May 2018Gastrointestinal (GI) nematode control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health... (Review)
Review
Gastrointestinal (GI) nematode control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health and welfare. In this synthetic review, we identify key research priorities for GI nematode control in farmed ruminants and pigs, to support the development of roadmaps and strategic research agendas by governments, industry and policymakers. These priorities were derived from the DISCONTOOLS gap analysis for nematodes and follow-up discussions within the recently formed Livestock Helminth Research Alliance (LiHRA). In the face of ongoing spread of anthelmintic resistance (AR), we are increasingly faced with a failure of existing control methods against GI nematodes. Effective vaccines against GI nematodes are generally not available, and anthelmintic treatment will therefore remain a cornerstone for their effective control. At the same time, consumers and producers are increasingly concerned with environmental issues associated with chemical parasite control. To address current challenges in GI nematode control, it is crucial to deepen our insights into diverse aspects of epidemiology, AR, host immune mechanisms and the socio-psychological aspects of nematode control. This will enhance the development, and subsequent uptake, of the new diagnostics, vaccines, pharma-/nutraceuticals, control methods and decision support tools required to respond to the spread of AR and the shifting epidemiology of GI nematodes in response to climatic, land-use and farm husbandry changes. More emphasis needs to be placed on the upfront evaluation of the economic value of these innovations as well as the socio-psychological aspects to prioritize research and facilitate uptake of innovations in practice. Finally, targeted regulatory guidance is needed to create an innovation-supportive environment for industries and to accelerate the access to market of new control tools.
Topics: Animals; Animals, Domestic; Anthelmintics; Biomedical Research; Communicable Disease Control; Gastrointestinal Diseases; Livestock; Nematoda; Nematode Infections; Protozoan Vaccines; Ruminants; Swine; Swine Diseases
PubMed: 29124904
DOI: 10.1111/tbed.12707