Intestinal mucosal transcriptomic responses of Asian seabass (Lates calcarifer) vaccinated with an oral hydrogel-encapsulated multivalent Vibrio antigen following Vibrio spp. infection

This study examined the intestinal mucosal immune responses elicited by an oral hydrogel-encapsulated multivalent Vibrio vaccine in Asian seabass (Lates calcarifer) to protect against vibriosis caused by Vibrio harveyi, V. vulnificus, and Photobacterium damselae (formerly Vibrio damsela). Both 7-day and 14-day oral vaccination regimens effectively enhanced innate and adaptive immune responses while supporting gut recovery post-infection. Transcriptomic analyses of intestines from fish that received consecutive 7- and 14-day vaccination regimens, followed by co-infection with multistrain Vibrio spp., revealed significant upregulation of innate and specific immune markers at week 8 post-vaccination. These responses were further bolstered by a strong adaptive immune activation, characterized by T-cell and B-cell receptor signaling as well as antibody production. In addition, the vaccine also demonstrated cross-protective immunomodulatory effects, evidenced by elevated interferon-related pathways (e.g., IFNAR2 and IFN-induced proteins), suggesting its potential to protect against co-infecting pathogens, a critical advantage in aquaculture systems facing diverse pathogen pressures. Beyond immune activation, the involvement proteins of TGF-β family members, including BMP3 and BMP4, highlights the vaccine's role in tissue repair and remodeling. These responses likely mitigate epithelial damage and preserve gut barrier integrity post-infection, showcasing the dual benefits of immunoprotection and post-infection recovery. The findings highlight the oral hydrogel-encapsulated multivalent Vibrio vaccine's ability to enhance immunity against specific bacterial pathogens while offering broader immunomodulatory and tissue-repair benefits. Its cross-protective and recovery-supporting properties make it a promising solution for sustainable aquaculture practices, effectively addressing pathogen control and boosting host resilience.