Objectives:One major objective is to proceed in our ongoing development of novel polymer based, controlled release delivery systems for fish vaccines to be used as tools for much more efficient and long term vaccination in farmed fish, as compared to convention vaccination. More specifically, we intend to 1. characterize the release kinetics of two fish vaccines from different types of plymer based biodegradable delivery systems. 2. administer the delivery systems to fish via different routes and monitor the long term defense mechanisms and immune response induced in fish. 3. treat fish with the most promising delivery systems and test the actual acquisition of resistance to disease.Methodology:We will incorporate two vaccines for major fish diseases, enteric red mouth and furunculosis, into three different controlled release, polymer based delivery systems. The release rates of the vaccines rom the delivery systems will be monitored using specific enzyme linked immunosrobant assays (ELISAs). The selected vaccine delivery system will be administered into rainbow trout via injection, immersion and oral routes. We will determine the potential of the delivery systems to induce intensive and long term: 1. specific immune response by monitoring, using ELISAs, level of specific antibodies induced in the fish and the number of splenic antibody producing cells, and 2. nonspecific defense mechanisms by monitoring neutrophil, leukocyte and phoagocytic activities. Finally, we will challenge the vaccinated fish with live pathogens and test for resistance to the disease. Rationale:Disease is a major problem in intensive aquaculture, resulting in substantial moralities and significant economic losses. vaccination is the only logical approach to overcome disease. However, for optimal vaccination, many of the presently available fish vaccines have to be repeatedly administered through individual injections, which is very labor intensive and stressful to the fish. We propose to develop a controlled release formulation for fish vaccines, which will be effective when administered by different routes and using only one application, for inducing intensive and long term protection against disease.