The cell surface is a functional interface between the inside and the outside of the cell. Moreover, cells have systems for anchoring surface specific
proteins and for confining
surface proteins to particular domains on the cell surface. For use in bioindustrial processes applied to oral vaccination, we consider that cell-surface display systems must be useful and that the yeast Saccharomyces cerevisiae, the most suitable microorganism for practical purposes, is available as a host for genetic engineering because it can be subjected to many genetic manipulations. In particular, the rigid structure of the cell makes the yeast suitable for several of the applications. In this study, we describe the expression of one of the target
antigens, 380R, from the red sea bream iridovirus (RSIV), which is one of the most common
viral diseases in the cultured marine fish Pagrus major in Japan, using the arming yeast system and aiming at its application for oral vaccination. We first performed the molecular cloning and expression of the 380R
antigen from RSIV in Escherichia coli. The nucleotide sequence of the 380R
antigen was composed of an open reading frame (ORF) of 1360 bp encoding a
protein of 453 residues. To prepare a specific antibody against the 380R
antigen, the
recombinant protein was overexpressed and purified in E. coli. As a result of indirect immunofluorescence with the specific antibody, we could observe the expression of the 380R
antigen on the surface of the yeast cells. Thus, we have successfully prepared the source of an oral
vaccine using cell-surface display technology in yeast.