Protective efficacy of novel oral biofilm vaccines against lactococcus garvieae infection in mullet, mugil cephalus
Journal
Vaccines
Journal Volume
9
Journal Issue
8
Date Issued
2021
Author(s)
Su F.-J
Abstract
Lactococcus garvieae (L. garvieae) is an important pathogen that causes enormous economic losses in both marine and freshwater aquaculture. At present, antibiotics are the only option for farmers to reduce the losses caused by L. garvieae. However, the usage of antibiotics leads to environmental pollution and the production of drug-resistant strains of bacteria. Therefore, vaccination is preferred as an alternative method to prevent infectious diseases. In this study, we describe an effective approach to the production of an oral biofilm vaccine, using bacteria grown on chitosan particles to form biofilms, and thus providing an inactive pathogen that enhances the immune response in fish. We observed the formation of a biofilm on chitosan particles and administered the novel oral biofilm vaccine to fish. We analyzed the immune responses, including antibody production, phagocytic ability, albumin/globulin ratio and immune-related genes, of vaccinated and control groups of black mullet. Our results show that the phagocytic ability of the biofilm vaccine group was 84%, which is significantly higher than that of the control group, and the antibody production in this group was significantly higher compared with the other group. The mRNA expression levels of immune-related genes (TLR2, IL-1β, TNF-α) were significantly upregulated in the spleen after vaccination. In challenge experiments, the relative percent survival (RPS) was 77% in the biofilm vaccine group, 18% in the whole-cell vaccine group, and 0% in the chitosan particle group at 32 days post-vaccination. In addition, we also found that the relative percent survival (RPS) at 1 day post-vaccination was 74% in the biofilm vaccine group, 42% in the whole-cell vaccine group, and 26% in the chitosan particle group. In both long-term and short-term challenge experiments, the viability of the biofilm vaccine group was significantly higher than that of the whole-cell, chitosan particle and PBS groups. We conclude that based on its protective effect, the L. garvieae biofilm vaccine is better than the whole-cell vaccine when challenged several weeks after vaccination. In addition, the biofilm vaccine also has a greater protective effect than the whole-cell vaccine when challenged immediately after vaccination. Therefore, the biofilm vaccine might represent a novel method for the prevention and treatment of L. garvieae infection. ? 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Subjects
IgM
Lactococcus garvieae
Mugil cephalus
Oral biofilm vaccine
acetic acid
agar
albumin
bacterial vaccine
chitosan
formaldehyde
globulin
horseradish peroxidase
interleukin 1beta
oral biofilm vaccine
phosphate buffered saline
polysorbate 20
RNA 16S
toll like receptor 2
tumor necrosis factor
unclassified drug
animal experiment
animal model
animal tissue
antibody production
aquaculture
Article
bacterial infection
bacterium isolation
biofilm
controlled study
drug efficacy
enzyme linked immunosorbent assay
gene expression level
immune response
immunohistochemistry
Lactococcus garvieae infection
mRNA expression level
nonhuman
polymerase chain reaction
real time polymerase chain reaction
relative percent survival
RNA isolation
RNA sequence
scanning electron microscopy
sea pollution
survival analysis
tissue section
Type
journal article