ConclusionsThis work developed an efficacious and safe vaccine againstS. iniae infection in farmed groupers. The vaccine produced adetectable specific antibody that offered protection against S.iniae infection for at least 6 months. Mortality of vaccinatedgroupers remained below 2%, while RPS exceeded 97%, implyingthat groupers treated with the tested vaccine mounted a protec-tive immune response against S. iniae. Moreover, the tested vaccinesignificantly elevated innate and adaptive immune responses, andregulated the expression of immune-related genes.