Protective Efficacy of Novel Oral Biofilm Vaccines against Photobacterium damselae subsp. damselae Infection in Giant Grouper, Epinephelus lanceolatus

Abstract

Photobacterium damselae subsp. damselae is a pathogen that mainly infects a variety of fish species. There are many antibiotic-resistant strains of Photobacterium damselae subsp. damselae. In a previously published article, we described the production method for a novel oral biofilm vaccine. In the study reported herein, we confirmed the protective effect of the oral biofilm vaccine against Photobacterium damselae subsp. damselae. Twenty-eight days after vaccination, phagocytosis increased by 256% relative to the control group. The mean albumin–globulin ratios of the vaccine groups were significantly lower than the mean albumin–globulin ratios of the control group. There were no significant intergroup differences in lysozyme activity. Mean IgM titers were significantly higher in the vaccine group than in the control group. There was a significant upregulation of the TLR 3, IL-1β, and IL-8 genes in the spleen 28 days after vaccination. The cumulative mortality of the control fish was 84% after challenging fish with the Photobacterium damselae subsp. damselae, while the cumulative mortality of the oral biofilm vaccine (PBV) group was 32%, which was significantly higher than those of the whole-cell vaccine (PWV) and chitosan particle (CP) groups. There is minimal published research on the prevention and treatment of Photobacterium damselae subsp. damselae infection; therefore, this oral biofilm vaccine may represent a new method to fill this gap.

Evaluation of feed utilization, immune response and disease resistance in striped catfish, Pangasianodon hypophthalmus (Sauvage 1878) fed with a novel Aeromonas hydrophila biofilm vaccine

“…A higher protection level (85.4%) was achieved through the oral vaccine against V. anguillarum biofilm was compared to the free cell vaccine (27%) in Asian seabass, Lates calcarifer [ 29 ]. Findings of the present study closely agree with the similar study conducted in Taiwan [ 56 , 57 ]. They had reported significantly higher RPS in biofilm vaccines against Lactococcus garvieae infection in Mullet (77%) and in Photobacterium damselae infection in giant grouper (62%).…”

An Introduction to Relevant Immunology Principles with Respect to Oral Vaccines in Aquaculture

“…A recent study demonstrated protection against Photobacterium damselae subsp. damselae in giant grouper (Epinephelus lanceolatus); this platform used a formalin-inactivated biofilm that was incorporated directly into the feed, which provided an RPS of 62% relative to the whole-cell formalin-inactivated vaccine [141]. This same biofilm vaccination method has also demonstrated protection against L. garvieae in mullet (Mugil cephalus) [142].…”