Title: VACCINE DEVELOPMENT: CURRENT POSITION AND PERSPECTIVES
Jenkins Mark C,
Submitted to: Coccidiosis International Conference Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 1994
Publication Date: N/A
Interpretive Summary: Coccidiosis, an intestinal disease caused by a single cell protozoan parasite, is estimated to cost the U.S. poultry industry in excess of $300 million annually. The primary control of this disease is through anticoccidial medication in the poultry feed, but serious problems with parasite drug resistance have occurred within the last 6 years which has reduced the effectiveness of these anticoccidials. Clearly, new forms or types of control are needed. One of the most promising areas in control is the use of genetically engineered parasite. The purpose of this paper is to review the most recent work done on the development of avian coccidial vaccines for use in the poultry industry. This includes the identification of coccidial antigens that may be potential vaccine candidates, and results from reported immunization trails in which protection was produced in birds given isolated or genetically engineered antigens. Conclusions derived from these studies were used in a discussion on the directions that should be pursued for successful use of coccidial vaccine.
Although hundreds of coccidial antigens from various developmental stages have been identified and characterized, only a few have been isolated in sufficient amounts or produced by recombinant technology for use in birds immunization trials. Results from these immunization trials. Results from these immunization studies are encouraging in that partial although not complete protection of up to four species of coccidia can be elicited in a number of chicken strains. In order to increase this level of protection in birds, it may be necessary to screen other antigens for their immunizing potential through use of cellular, humoral and hybridoma antibodies. It is also possible that the antigens for eliciting greater protection are already identified and available through use of recombinant technology and cell culture techniques. What may be needed is the proper presentation of these antigens in the correct structural configuration to increase protection in an immunized bird, and use of modified battery and floorpen models to evaluate the extent of protection. It has been shown with recombinant antigens that the genetic makeup of the bird (specifically the MHC genes), type and site of antigen delivery, number of antigens used and the antigen fusion partner are all important in eliciting greater protective immune response. Further work is necessary on the interaction of these variables and the choice of adjuvants, immunopotentiators and viral or bacterial vectors in order to enhance protection.