Zebrafish (Danio rerio) has emerged as an important experimental system to study both vertebrate immunity and as a model system for fish immunology. Studies in this species have already revealed important knowledge about fish-pathogen interactions and fish vaccinology. Although more than 18 different Toll-like receptors (TLRs) have been genomically identified in fish, little is known about their agonists and functional role in fish immunity. We have established a NFkB-luciferase reporter system to analyse agonist profiles for several fish TLRs. In addition, after adaption of zebrafish to 15°C the protective effects of various TLR ligands alone and as adjuvants for DNA vaccination against surface proteins from cold water pathogens like viral hemorrhagic septicemia virus (VHSV) have been investigated. We also investigated the activation of zebrafish leucocytes by TLR ligands and recombinant G protein from VHSV (VHSV-G) in vitro. Our results demonstrate that poly I:C (TLR3 agonist) induce inflammatory transcripts in vitro. In vivo, one injection of poly I:C, could partially protect zebrafish against subsequent VHSV infection. The onset of mortalities was delayed by ten days (day 20 compared to day 10 in control) in the poly I:C treated fish. We will also present interesting results showing the effects of formulating plasmid DNA vaccines against VHSV-G with various TLR agonists included as adjuvants (on-going studies)

Poster.-- Immunology AAI Annual Meeting, Honolulu (Hawaii), 03-07 May 2013

Peer reviewed