A recombinant vaccine targeting the parasitic ciliate Ichthyophthirius multifiliis

New vaccine candidates were identified targeting the one celled parasite Ichthyophthirius multifiliis, which negatively affects aquaculture freshwater fish productions all over the world. In silico selection with the use of artificial intelligence identified several potential vaccine candidates and three of these were recombinantly expressed using E. coli and insect cells. Following a vaccine trial one protein (a so-called neurohypophysial n-terminal domain protein, #10) was found to induce moderate protection against I. multifiliis in rainbow trout (Oncorhynchus mykiss). To develop a highly protective heterologous vaccine we aim to combine #10 with a protective epitope from the already known homologous protective antigen Iag52b, which is a GPI-anchored cysteine rich surface protein. To be able to produce #10 at low costs, recombinant expression has been conducted in an eukaryotic host. Purified Iag52b does not induce immunity in fish without the use of adjuvants, thus the most potentially protective epitope of Iag52 was selected in silico and coupled to a virus-like particle. This coupling enables the epitope to be presented in a virus-like conformation, which theoretically should be immunogenic to the fish