AVIAN INTESTINAL IMMUNITY - BASIC MECHANISMS AND VACCINE DESIGN

Progress in our understanding of the structure, function and mechanism s of the avian intestinal immune system are reviewed. In particular, t he afferent and efferent sites of the intestinal immune system and the ir maturation and interaction for the generation of a local antigen-sp ecific IgA antibody response are examined. With advances in the elucid ation of the basic mechanisms involved in the induction of an immune r esponse at the avian intestinal mucosa, evaluation of vaccination tech niques for stimulation of the immune system is likely to prove fruitfu l. While differences exist between species in the operation of the imm une system, recent developments in the design and delivery of vaccines for the generation and manipulation of mucosal immune responses in ma mmalian species justify an appraisal of their functionality in chicken s. The vaccination strategies discussed include the delivery vehicle, the mucosal adjuvant and the route of delivery of the antigen. The lim ited number of publications evaluating these immunization strategies i n chickens highlights the need for closer scrutiny of their efficacy i n the regulation of mucosal immunity in this species. Further, in mamm alian species the regulatory influence of T cells, and in particular t heir cytokine profiles, on the production of IgA antibody is intently debated, however, advances in this area of avian immunology are hinder ed by the limited number of sequenced and cloned avian cytokines and t heir antibodies. However, it is through cytokine manipulation that the most significant advances in mucosal vaccines are likely to be achiev ed, particularly if coupled with the delivery of antigen in appropriat e adjuvant/vehicle formulations.