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Swine respiratory diseases have induced severe economic losses in swine industry worldwide. Several methods have been developed and applied to prevent and control the disease. However, those are still problematic in swine industry. Recently, the use of egg yolk antibodies with several advantages was introduced and applied to control diseases in animal as well as human. As the first step of the use of egg yolk antibodies in the control of the swine respiratory diseases, we investigated the immunogens of the causative agensts of the diseases and immune response in egg yolk of hens immunized with them. Bacterial antigens prepared from Bordetella bronchiseptica, Pasteurella multocida 3A and 4D, and Actinobacillus pleuropneumaniae serotype 2 and 5 were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot and toxicity test in mice. The antigens were injected into laying hens in order to produce antibodies against them in egg yolk. After chickens were immunized three times in 2 weeks interval, the profile of antibody production was examined by ELISA. The production of antibody in egg yolk was started in 2 weeks after the first injection, reached peak in 6-8 weeks and maintained until 12 weeks. Of two adjuvants used in this study, ISA70 was more effective than aluminum hydroxide gel in enhancing immunogenecity, laying rates and safety in hens. These results suggested that egg yolk antibodies could be a good source for production of antibodies specific to pathogenic bacteria inducing respiratory diseases of swine.
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