Recombinant vaccines against infectious hematopoietic necrosis virus: production by the Caulobacter crescentus S-layer protein secretion system and evaluation in laboratory trials.

We report the development of an IHNV vaccine produced by a new protein production system based on the bacterium Caulobacter crescentus. The subunit vaccines that were tested con- tain a 184 amino acid segment of the IHNV glycoprotein in different fusion arrangements with the C. crescentus S-layer protein. Relative percent survival of 26 to 34% was demonstrated in rainbow trout fry for a vaccine that contained the 184 amino acid segment of the IHNV glycoprotein fused to the C- terminal one-quarter of the S-layer protein. Inclusion of the universal mammalian T-cell epitopes developed from the measles fusion protein or the tetanus toxin protein did not increase the effective- ness of the IHNV-G/S-layer recombinant protein.