A Combinatorial Approach to Vaccine Development for Fish

Objectives:  Bacterial Kidney Disease (BKD) is the most economically important disease of wild and farmed salmonids. Currently, there are no effective vaccines or treatments for BKD. Our overall objective is to develop BKD vaccines for fish. Our strategy is:  1) to use a combinatorial phage display library to identify novel antigens for BKD. 2) express those antigens in microalgae 3) deliver microalgae expressing BKD antigens to fish via feed or by immersion, and 4) to determine whether the microalgal-BKD antigen delivery system provides protection against BKD (vaccination). We propose that our vaccine development strategy will have broad applications for many disease systems including those in which it is not possible to isolate or grow the pathogen.  Rationale:  BKD is a major disease of fresh-water and marine salmonids resulting in substantial mortality. The disease is slow to manifest symptoms and therefore is difficult to treat with antibiotics. As a result, BKD is a prime candidate for the development of an effective vaccine treatment. To date, traditional approaches to identifying and delivering vaccines to trout for BKD control have proven ineffective. We propose that a combinatorial antigen discovery strategy will lead to the rapid identification of novel vaccine immunogens. The delivery of these immunogens in microalgae will induce an immune response both in serum and in mucus, providing the best possible protection against BKD.