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

Feng-Jie Su,Meei-Mei Chen

doi:10.3390/vaccines10020207

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.

Highlights

Epinephelus lanceolatus is taxonomically classified among the Chordata, Neopteridae, Perciidae, and Serranidae in the genus Epinephelus
Photobacterium damselae subsp. damselae is a Gram-negative bacterium that mainly infects a variety of marine fish
Photobacterium damselae has two main subspecies, Photobacterium damselae subsp. damselae and Photobacterium damselae subsp. piscicida, both of which are associated with high rates of mortality among marine species [4,5,6,7]

Summary

Introduction

Epinephelus lanceolatus (giant grouper) is taxonomically classified among the Chordata, Neopteridae, Perciidae, and Serranidae in the genus Epinephelus. The species is an important cultured fish species in Asia [1]. In the process of aquaculture, it is highly susceptible to viral and bacterial infections, which results in decreased production. Damselae is a Gram-negative bacterium that mainly infects a variety of marine fish. Damselae was first named Vibrio damsel until it was renamed in 1995 after 16S rRNA gene sequence analysis. Photobacterium damselae has two main subspecies, Photobacterium damselae subsp. Piscicida, both of which are associated with high rates of mortality among marine species [4,5,6,7] Photobacterium damselae has two main subspecies, Photobacterium damselae subsp. damselae and Photobacterium damselae subsp. piscicida, both of which are associated with high rates of mortality among marine species [4,5,6,7]

Methods

Results

Conclusion