CpG‐ODN 2007 protects zebrafish ( Danio rerio ) against Vibrio vulnificus infection

Abstract

Vibrio vulnificus is an aquatic pathogen that can cause primary sepsis and soft tissue infection. CpG oligodeoxynucleotides (CpG-ODN) are a type of essential immunomodulators, which can trigger or enhance immune responses in mammals, fish and humans. In this study, we evaluated the effect of CpG-ODN 2007 as a potential immunostimulant for zebrafish (Danio rerio) infected with V. vulnificus strain FJ03-X2. Fish injected with the CpG-ODN 2007 showed a lower mortality rate compared with the fish that did not receive treatment; the survival rates of the CpG-ODN 2007-treated group and PBS-treated group were 85% and 57.9% respectively. Also, our in vitro results demonstrated that CpG-ODN 2007 could effectively reduce the toxicity of V. vulnificus strain FJ03-X2 to zebrafish embryonic fibroblast (ZF4) cells. Furthermore, we assessed innate immune-related genes (TNF, IL-1β, IFNg1-2, MyD88, lysozyme, IL-10, IL-22, IL-26 and TLRs) in expression patterns of V. vulnificus strain FJ03-X2 infected zebrafish or ZF4 cells with and without CpG-ODN 2007 treatment. We found that CpG-ODN 2007 could reduce the toxicity of V. vulnificus to ZF4 cells and regulate the immune system to control the overexpression of specific genes. To sum up, our data indicated that CpG-ODN 2007 protects zebrafish against Vibrio vulnificus infection.