Analysis of Tissue-Specific Interferon Regulatory Factor 3 (IRF3) Gene Expression against Viral Infection in Paralichthys olivaceus

Interferon Regulatory Factor 3 (IRF3) is a member of interferon-regulated transcription factor family and is known to play an important role in the innate immune response against viral infections. In this study, the expression of IRF3 in different tissues, developmental stages, and stocking densities of olive flounder was investigated. The expression of IRF3 was observed to gradually increase in early-stage juvenile fish. The highest expression was observed in later-stage juvenile fish when immune tissues were formed. High IRF3 expression was observed in the muscles and the brain tissues. The expression of IRF3 was observed in fish at different stocking densities after viral hemorrhagic septicemia virus (VHSV) infection. It yielded an interesting expression pattern in the muscles and the brain tissues of fish stocked at low density. These observations can be used as basic data for the study of the expression of immune response-related genes against viruses based on stocking density and immune systems in other fish species.