O-021. Application and Development of the Arming Yeast System to Oral Vaccination for the Cultured Marine Fishes

Y. Tamaru;
Mie Univ., Mie-ken, JAPAN.

The establishment of systems to display heterologous proteins on the cell surface of microorganisms is expected to be useful in the separation of produced polypeptides; the production of microbial biocatalysts, whole-cell adsorbents, and live vaccines; and the screening of modified or novel proteins. Thus, since cell-surface display is a promising approach in protein engineering, by using the cell-surface engineering system in S. cerevisiae, we tried to express the 380R antigen from red sea bream iridovirus (RSIV), which is one of famous viral diseases in the cultured marine fish. First, we have cloned the 380R antigen from RSIV and purified the recombinant 380R from Escherichia coli. 200μl of the purified recombinant 380R antigen (approx. 0.8mg/ml) was injected and the antiserum was collected from two rabbits. Western-blot analysis revealed that anti-380R antigen antibody immunoreacted with the recombinant proteins in E. coli. Next, we tried to detect the expression of the recombinant protein on the outside of the yeast cells by using the antibody. As a result, the recombinant 380R antigen on the yeast cells was detected by immunofluorescence labeling methods. Finally, we tried to use whether the display system of arming yeast could be applied for oral vaccination in RSIV. RSIV infection test towards Oplegnathus fasciatus clearly indicated that the arming yeast carrying the recombinant 380R antigen immediately decreased mortality rate. Further work is needed to analyze the immunological system in fish and to show whether the arming yeast carrying the candidate for target antigens from RSIV and how oral vaccination works in the red sea bream.