Protection of Grouper Againstby Immunization Withand Protective Cross-Reactive Antigen Identification.

Abstract

Vaccination is an effective method to preventinfection. Although some vaccines have been developed, large-scale production of these vaccines is costly. Development of a heterogenous vaccine generated by low-cost antigens is an alternative method. In the present study, grouper immunized with, a free-living ciliate that easily grows in inexpensive culture media at high density, showed protective immunity againstinfection. Higher immobilization againsttheronts was detected in-immunized grouper serum, which suggested the existence of a cross-reactive antibody in the serum. By immunoprecipitation and mass spectrometry analyses, tubulin was identified as a potential cross-reactive antigen betweenand. Recombinanttubulin protein (rTt-tubulin) and its antibody were prepared, and immunofluorescence showed that bothandcilia were stained by the anti-rTt-tubulin antibody. Grouper immunized with rTt-tubulin showed a reduced infective rate after thechallenge. An enhanced level of-binding immunoglobulin M (IgM) antibody was detected in serum from rTt-tubulin-immunized grouper. Moreover, specific antibodies were also found in the mucus and tissue culture medium from rTt-tubulin-immunized grouper. Overall, these findings suggested that vaccination withelicits cross-reactive protective immunity in grouper against, andmay be a potential heterologous antigen for vaccine development.