TNF-α and interleukin 10 genes expression in rainbow trout in response to viral hemorrhagic septicemia virus (VHSV) infection

Among the essential metabolic functions of the liver, the role of this tissue as a mediator in the immune system has also been considered. Although the role of cytokines and chemokines in mammalian immune systems has been well evaluated, few studies have been performed in fish. Genes involved in the immune system, such as interleukin 10 and TNF-α, play an important role in the immune system of various cells. In the present study, the expression of interleukin 10 and TNF-α genes in rainbow trout was assessed following VHS virus treatment. Six samples from each of two control group and infected group with VHS virus were selected and then total RNA was extracted from liver tissue. The differential expression of interleukin 10 and TNF-α genes between the two studied groups (infected with the virus vs control) was assessed using Real-Time PCR. Comparison of relative changes in gene expression were assessed by statistical methods in three replications of each sample. Analysis of data showed that the expression of interleukin 10 and TNF-α genes increased in response to VHS virus. In this study, although the expression of both interleukin 10 and TNF-α genes were significantly increased, but the rate of interleukin 10 expression in the treatment group was 25 times higher than the control group. Increased expression of these two cytokines, in particular over induction of interleukin 10 expression by the virus may lead to impaired of immune function. As a final conclusion, studying the relative changes of cytokine genes expression can increase our knowledge on molecular mechanism of immune function against pathogens. In this case, it is possible to develop molecular markers in order to increase resistance to viral disease in breeding programs of industrial fish farming.