• Korean Journal of Poultry Science
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• v.26 no.3
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• pp.149-170
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• 1999

Protozoa of the genus Eimeria are the etiologic agents of avian coccidiosis, the most economically important Parasitic disease for the poultry industry. Coccidia multiply in intestinal epithelial cells of a wide range of hosts, including livestock in addition to poultry. Chemotherapy is extensively used to control coccidiosis. However, development of drug resistance by Eimeria parasites, the intensive cost and labor involved in the identification of new anticoccidial compounds and public awareness of drug residues in foods warrant alternative methods to prevent coccidiocic in the fast growing poultry industry. For these reasons, there is a great interest in developing vaccines against avian coccidiosis. Live Eimeria vaccines confer protective immunity, however a significant disadvantage of using these types of vaccines is their pathogenicity. Live parasites with attenuated pathogenicity also usually produce immunity but may revert back to a pathogenic form and may be contaminated with other pathogenic organisms. Killed Eimeria vaccines are safer but, unlike live attenuated vaccines, are not able to generate cytotoxic T lymphocyte responses. Recombinant vaccines are biochemically purified proteins produced by genetic engineering that consist of particular epitopes or metabolites of Eimeria. Unlike live attenuated organisms, recombinant vaccines do not possess as much risk and generally are able to induce both humoral and cell mediated immunity. DNA vaccines consist of genes encoding immunogenic proteins of pathogens that are directly administered into the host in a manner that the gene is expressed and the resulting protein generates a protective immune response. Although all of these different types of vaccines have been applied to coccidiosis, this disease continues to cause substantial morbidity and mortality in the poultry industry. Future development of an effective vaccine against coccidiosis will depend on further investigation of protective immunity to Eimeria infection and identification of important immundgenic parasite molecules.

• Korean Journal of Poultry Science
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• v.20 no.1
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• pp.17-31
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• 1993

Several aspects about the epidemiological status of chicken coccidiosis, its control measures and recent research activities in Korea are discussed in this paper. Medication with different available anticoccidial drugs has been reasonably effective in treating and preventing serious outbreaks of coccidiosis in chicken, but the disease remains one of the most expensive and common diseases of popultry production in this country, and more recently its incidence is increasing, possibly due to the more intensive methods of husbandry and the immergence of resistant strains of coccidia. Therefore, this necessitates a continuous search for new methods such as medication program (shuttl and rotation program) and immunization using attenuated strains or parasite antigens.

• Korean Journal of Poultry Science
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• v.26 no.2
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• pp.131-144
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• 1999

Coccidiosis, an intestinal infection caused by intracellular protozoan parasites belonging to several different species of Eimeria seriously impairs the growth and feed utilization of livestock and poultry. Due to complex life cycle of organism and intricate host immune responses to Elmeria, coccidia vaccine development has been difficult. Understanding of basic imunobiology of pertinent host-parasite interactions is necessary for the development of novel control strategy. Although chickens infected with Eimeria spp. produce parasite-specific antibodies in both the circulation and mucosal secretions, antibody mediated responses play a minor role in protection gainst coccidiosis. Rather, increasing evidence show that cell-mediated immunity plays a major role in resistance to coccidiosis. T-lymphocytes appear to respond to coccidiosis both through cytokine production and a direct cytotoxic attack on infected cells. The exact mechanisms by which T-cells eliminate the parasites, however, remain to be investigated. Since it is crucial to understand the intestinal immune system in order to develop an immunological control strategy against any intestinal immune system in order to develop an immunological control strategy against any intestinal diseases, this presentation will summarize our current understanding of the avian intestinal immune system and mucosal immune responses to Eimeria, to provide a conceptual overview of the complex molecular and cellular events involved in intestinal immune responses to enteric pathogens.

• Parasites, Hosts and Diseases
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• v.51 no.2
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• pp.147-154
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• 2013

To control coccidiosis without using prophylactic medications, a DNA vaccine targeting the gametophyte antigen Gam56 from Eimeria maxima in chickens was constructed, and the immunogenicity and protective effects were evaluated. The ORF of Gam56 gene was cloned into an eukaryotic expression vector pcDNA3.1(zeo)+. Expression of Gam56 protein in COS-7 cells transfected with recombinant plasmid pcDNA-Gam56 was confirmed by indirect immunofluorescence assay. The DNA vaccine was injected intramuscularly to yellow feathered broilers of 1-week old at 3 dosages (25, 50, and $100{\mu}g/chick$). Injection was repeated once 1 week later. One week after the second injection, birds were challenged orally with $5{\times}10^4$ sporulated oocysts of E. maxima, then weighed and killed at day 8 post challenge. Blood samples were collected and examined for specific peripheral blood lymphocyte proliferation activity and serum antibody levels. Compared with control groups, the administration of pcDNA-Gam56 vaccine markedly increased the lymphocyte proliferation activity (P<0.05) at day 7 and 14 after the first immunization. The level of lymphocyte proliferation started to decrease on day 21 after the first immunization. A similar trend was seen in specific antibody levels. Among the 3 pcDNA-Gam56 immunized groups, the median dosage group displayed the highest lymphocyte proliferation and antibody levels (P<0.05). The median dosage group had the greatest relative body weight gain (89.7%), and the greatest oocyst shedding reduction (53.7%). These results indicate that median dosage of DNA vaccine had good immunogenicity and immune protection effects, and may be used in field applications for coccidiosis control.

• Korean Journal of Poultry Science
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• v.34 no.1
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• pp.77-83
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• 2007

Poultry products including meat and eggs constitute a major protein source in the American diet and disease-causing pathogens represent major challenges to the poultry industry. More than 95% of pathogens enter the host through the mucosal surfaces of the respiratory, digestive and reproductive tracts and over the past few decades, the two main mechanisms used to control diseases have been the use of vaccines and antibiotics. However, in the poultry industry, there are mounting concerns over the ability of current vaccines to adequately protect against emerging hyper-virulent strains of pathogens and a lack of suitable, cost effective adjuvants. Thorough investigation of the immunogenetic responses involved in host-pathogen interactions will lead to the development of new and effective strategies for improving poultry health, food safety and the economic viability of the US poultry industry. In this paper, I describe the development of immunogenomic and proteomic tools to fundamentally determine and characterize the immunological mechanisms of the avian host to economically significant mucosal pathogens such as Eimeria. Recent completion of poultry genome sequencing and the development of several tissue-specific cDNA libraries in chickens are facilitating the rapid application of functional immunogenomics in the poultry disease research. Furthermore, research involving functional genomics, immunology and bioinformatics is providing novel insights into the processes of disease and immunity to microbial pathogens at mucosal surfaces. In this presentation, a new strategy of global gene expression using avian macrophage (AMM) to characterize the multiple pathways related to the variable immune responses of the host to Eimeria is described. This functional immunogenomics approach will increase current understanding of how mucosal immunity to infectious agents operates, and how it may be enhanced to enable the rational development of new and effective strategies against coccidiosis and other mucosal pathogens.

• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.129-132
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• 1998

Avian coccidiosis is a very important disease of poultry industry. In recent years, many researchers studied for the immunology of avian coccidiosis. Coccidial vaccines have been used at some poultry farms in many countries. In order to evaluate the anticoccidial effects of coccidial vaccine to chicken treated with anticoccidial drugs, 4 week-old chicken were administered anticoccidial drugs and challenged with avian coccidia at 2 weeks after vaccination of coccidia. The body weight gains, lesion scores, oocyst indices and anticoccidial indices of chicken were investigated at the time of vaccination, challenge and necropsy. The body weight gains and feed conversion rates of groups immunized with coccidial vaccine and treated with anticoccidial drugs were moderately higher and lower than those of groups treated with anticoccidial drugs, respectively. The lesion score and oocyst indices of all groups immunized with coccidial vaccine and/or treated with anticoccidial drugs were milder than those of infected control groups. The anticoccidial indices of groups immunized with coccidial vaccine and treated with anticoccidial drugs were moderately higher and lower than those of groups. treated with anticoccidial drugs. But all of the investigated items were not statistically significant.

• Korean Journal of Poultry Science
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• v.38 no.4
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• pp.275-284
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• 2011

As the world population grows and developing countries become more affluent, the global consumption of meat will increase by more than 50% within the next 10 years. Confronting the increased demand for poultry food products are emerging field diseases, increasing regulatory bans of antimicrobial growth promoters, high-density growth conditions, and waste management. Although biotechnology offers solutions to some of these challenges, basic studies are needed to better understand the complex interaction between the intestinal microbiome, host immunity and the environment. This presentation will focus on emerging strategies to enhance gut immunity and to decrease economic losses due to poultry diseases. This presentation will highlight recent developments in coccidiosis research and provide information on host immunity, immunomodulation, and the latest advances in dietary and nutritional approaches against coccidiosis. Such information will magnify our understanding of host-parasite biology, mucosal immunology, and design of future nutritional interventions and vaccination strategies for coccidiosis.

• Journal of Veterinary Clinics
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• v.12 no.1
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• pp.911-916
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• 1995

Ionophorous antibiotics have been used popularly for the protection of avian coccidiosis, though Halo-fuginone which is derived from an extract of the Dichroa febrifuga, was developed as an antimalarial and anticoccidial agent. The antibiotics are regarded as the causes of residues in the avian products, therefore the author has tried to find out more safe herbal materials for the control of avian coccidiosis. Thus, the extracts of 5 kinds of herbs, roots of Pulsatilla koreana Nakai and Sophora flavescens Aiton, nuts of Quisqualis indica Linne, whole herbs of Artemisia annua Linne and Polygonum aviculare Linne, were investigated on the efficacy against E tenella. Survival rates, bloody diarrhea, lesion scores, body-weight gains and feed conversion rate were investigated at the 1st and the 2nd week after infection. The bloody diarrhea in the groups treated with P koreana, A annua, Q indica and P aviculare were milder than those in the groups treated with S flavescens and infected control. The lesion score in the groups treat.4 with herb extracts(2.00$\pm$0.82~2.65$\pm$0.89) were lower than those in the control group (2.80$\pm$0.7l). But, there was not significant in all infected groups. The body weight gai in the groups treated with P koreana, S flavescens, A annua and Q indica(291.74$\pm$15.76~303.43$\pm$51.90) were higher than that in the control group (283.71$\pm$16.53) but there was not significant. In a conclusion, analyzing the data of the survival rates, bloody diarrheal symptoms, lesion scores, body weight gains and oocyst excretions, the extract of S flavescens, P koreana, A annua and Q indica were effective. The further research on the above herbal materials will have been carried out by the author and the other researchers by means of the chemical analysis of the components.

• Korean Journal of Poultry Science
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• v.19 no.3
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• pp.151-160
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• 1992

Control of coccidiosis depends on medication, management, immunity, or some combination of these methods. Prophylactic medication with anticoccidials remains the primary method of control, although the development of drug resistance is a major problem. Shuttle and rotation programs are increasingly used to delay the onset of drug resistance. Sensitivity testing has become an important tool in the identification of what specific medications will be effective in specific poultry operations. Management techniques for the control of coccidiosis have not been totally effective because most disinfectants do not kill the coccidial oocysts. Present methods for vaccination are currently limited to the use of controlled doses of live coccidia. New vaccination methods under investigation include vaccination with attenuated strains or parasite antigens produced either by fractionating the parasites or genetically engineered sub unit vaccines.

• Korean Journal of Poultry Science
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• v.38 no.4
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• pp.323-330
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• 2011

The chicken monoclonal antibody (mAb), 13C8, reacts with sporozoite antigens of Eimeria spp. which causes avian coccidiosis. Since this mAb was produced at low amount due to genetic instability of chicken hybridoma, a recombinant 13C8 single-chain Fv (ScFv) antibody was constructed by amplification of the variable domain of heavy (VH) and light chain (VL) genes of antibody derived from chicken hybridoma. The constructed 13C8 ScFv was successfully expressed in E. coli and purified as a soluble form. In ELISA analysis, this recombinant 13C8 ScFv antibody showed antigen binding activity as the original mAb. In addition, nucleotide sequence comparison of 13C8 gene to the germline chicken VL and VH genes suggested that the gene conversion with $V{\lambda}$ and VH pseudogenes might contribute to the diversification of VL and VH genes in chickens.