AUTHOR=Yang Jun , Yang Xiao-li , Su Yu-bin , Peng Xuan-xian , Li Hui 

TITLE=Activation of the TCA Cycle to Provide Immune Protection in Zebrafish Immunized by High Magnesium-Prepared Vibrio alginolyticus Vaccine

JOURNAL=Frontiers in Immunology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.739591

DOI=10.3389/fimmu.2021.739591

ISSN=1664-3224

ABSTRACT=<p>Vaccines are safe and efficient in controlling bacterial diseases in the aquaculture industry and are in line with green farming. The present study develops a previously unreported approach to prepare a live-attenuated <italic>V. alginolyticus</italic> vaccine by culturing bacteria in a high concentration of magnesium to attenuate bacterial virulence. Furthermore, metabolomes of zebrafish immunized with the live-attenuated vaccines were compared with those of survival and dying zebrafish infected by <italic>V. alginolyticus</italic>. The enhanced TCA cycle and increased fumarate were identified as the most key metabolic pathways and the crucial biomarker of vaccine-mediated and survival fish, respectively. Exogenous fumarate promoted expression of <italic>il1β</italic>, <italic>il8</italic>, <italic>il21</italic>, <italic>nf-κb</italic>, and lysozyme in a dose-dependent manner. Among the five innate immune genes, the elevated <italic>il1β</italic>, <italic>il8</italic>, and <italic>lysozyme</italic> are overlapped in the vaccine-immunized zebrafish and the survival from the infection. These findings highlight a way in development of vaccines and exploration of the underlying mechanisms.</p>