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Title: Protection Against Coccidiosis: Role of passive immunity (immediate immunity) mediated by hyperimmune IgY antibodies

item Lillehoj, Hyun

Submitted to: Review Article
Publication Type: Review Article
Publication Acceptance Date: 12/1/2009
Publication Date: 4/5/2010
Citation: Lillehoj, H.S., Lucio, E. 2010. Protection against Coccidiosis: Role of Passive Immunity (Immediate Immunity) mediated by hyperimmune IgY antibodies. Association National de Especialistas en Ciencias Avicolas de Mexica (ANECA), Acapulco, Mexico. Review Article. p. 13-20.

Interpretive Summary: Although prophylactic use of anti-coccidia feed additives has been the primary method of controlling avian coccidiosis, alternative control methods are needed due to increasing concerns with prophylactic drug use and high cost of vaccines. In this review, ARS scientists discuss passive immunization technology to control avian coccidiosis which costs the industry greater than $3 billion in annual losses worldwide. Dr. Lillehoj working with Dr. Lucio at the Investigacion Aplicada, S. A. (IASA), Puebla, Mexico, evaluated the effects of feeding IgY fraction of egg yolk prepared from hens hyperimmunized with multiple species of Eimeria oocysts to the diets of young broilers, and found it was protective against coccidiosis. This type of passive immunity using therapeutic application of antibodies which are specific against target antigens of interest is safe and its development is increasingly becoming important and economically feasible. The IgY antibodies in the yolk of avian eggs is an alternative to the serum antibodies because of its feasibility to produce large scale for commercial application, and the relative non-invasiveness of collection. These results clearly indicate potential of using chicken egg antibodies (IgY), to reduce the body weight loss and decrease the fecal oocyst shedding to reduce economic loss due to avian coccidiosis. This type of strategy can also be applied to prevent other mucosal pathogens including E. coli and Salmonella and will have significant impact in raising drug-free poultry.

Technical Abstract: Avian coccidiosis is a major parasitic disease of poultry with substantial economic consequences estimated to cost the industry greater than $3 billion in annual losses worldwide. Coccidiosis is caused by several distinct species of the genus Eimeria that infect the gut and are transmitted between birds via ingestion of infective oocysts. Eimeria possess a complex life cycle comprising of both sexual and asexual stages, are host- and infection site-specific, and their pathogenicity varies in birds of different genetic backgrounds. Although good management practices and live vaccination with prophylactic medication have helped to reduce the spread of coccidiosis, the poultry industry are faced with several challenges and new alternative control strategies need to be developed for the following reasons: 1) evidence of increasing incidence of drug-resistant Eimeria strains, 2) limited availability of new drugs, 3) absence of knowledge about drug-resistance mechanisms, 4) lack of cross-protection mediated by live/attenuated parasite vaccines, and 5) limited understanding of protective immune mechanisms. While natural infection with Eimeria spp. induces both antibody and cell-mediated immunity (CMI) which are specific for the antigens that initiates immunity, numerous experimental evidences indicate that CMI plays a major role in protection against reinfection with homologous species of Eimeria. Antibodies, although produced in serum and in secretions during coccidiosis, show low titers and their target antigen specificity may not be ideal for protection against reinfection. In recent years, several different live vaccines composed of either virulent or attenuated coccidian strains have been commercially developed.