Abstract

Large yellow croaker (Larimichthys crocea), an economically important marine fish in China, has suffered from serious vibriosis, which has resulted in great economic losses for the large yellow croaker industry. Vaccination has been considered to be a safe and effective method to prevent and control vibriosis. However, due to the complex diversity and serotypes of theVibriogenus, the progress ofVibriovaccine development is still slow. In this study, we prepared recombinantVibriodihydrolipoamide dehydrogenase (rDLD) protein and investigated its potential as a candidate to be a subunit vaccine againstVibrio. The lysozyme activity and the rDLD-specific antibody level in sera of large yellow croakers immunized with rDLD were significantly higher than those in the control group, and the transcript levels of proinflammatory cytokines (IL-6,IL-8,IL-1β),MHC IIα/β,CD40,CD8α,IL-4/13A, andIL-4/13Bwere significantly up-regulated in the spleen and head kidney of large yellow croakers immunized with rDLD, suggesting that rDLD could induce both specific and nonspecific immune responses in this species. In addition, rDLD protein increased the survival rate of large yellow croakers againstVibrio alginolyticusandVibrio parahaemolyticus, with the relative percent of survival (RPS) being 74.5% and 66.9%, respectively. These results will facilitate the development of a potential subunit vaccine againstVibrioin large yellow croaker aquaculture.Keywords:dihydrolipoamide dehydrogenase;subunit vaccine;Vibrio;relative percent survival rate;Larimichthys crocea