Recombinant interferon-gamma activates immune responses against Edwardsiella tarda infection in the olive flounder, Paralichthys olivaceus

Abstract

Interferon gamma (IFN-gamma) is a cytokine that plays a very important role in defining Th1 immune response in all vertebrates. In this study, recombinant IFN-gamma (rIFN-gamma) from the olive flounder (Paralichthys olivaceus) was produced in an Escherichia coli system using a pET expression vector. Stimulation of whole kidney leukocytes (immune-related cells) in vitro with the resulting rIFN-gamma significantly induced the gene expression of interleukin-1 beta (IL-1 beta), signal transducer and activator of transcription 1 (STAT1), CXCL13-like chemokine (CXCL13), and IFN-gamma. rIFN-gamma also weakly induced the expression of IL-1 beta, tumor necrosis factor-alpha (TNF-alpha). CXCL13, and IFN-gamma in olive flounder-derived HINAE (non-immune) cells. The effects of rIFN-gamma against Edwardsiella tarda infection in vivo were assessed by intraperitoneally injecting a mixture of rIFN-gamma (100 ng) and E. tarda (1 x 10(5) CFU/ml) into the olive flounder. The survival rate in the rIFN-gamma-injected group was 60% compared to 0% in the group treated with E. tarda only, demonstrating that olive flounder IFN-gamma is effective in reinforcing immune responses and preventing against edwardsiellosis. (C) 2012 Elsevier Ltd. All rights reserved.