Effects Of Reticuloendotheliosis Virus Infection On Interleukin-2Production In The Primary Immune Organs Of SPF Chickens

Interleukin-2is a cytokine produced by activated T lymphocytes, this cytokine inducedT cell proliferation, promote B cell differentiation and secretion of antibodies induced byother cellsfactor, enhanced mononuclear cells, the cytotoxic activity of NK cells and LAKcells in the immune response has a very important role in immune regulation. Therefore, IL-2will play an important role in basic research and clinical applications of many diseases. Nowintensive immuno suppressive disease has brought great harm to the poultry industry in China.There have been many reports that REV(Reticuloendotheliosis virus, REV) infection cancause serious immunosupression of humoral and cell-mediated immune responses.Understanding the mechanism of immunosuppression and developing strategies to improvethe immune responses of chickens have become the current research hotspots. In this study,immunosuppression caused by REV was used as a model and the role of chicken IL-2in theimmune suppression was discussed. And this study was divided into two parts:1. A real-time reverse-transcription PCR(RRT-PCR) was developed successfully fordetecting chicken IL-2which based on SYBR Green I. According to the chicken IL-2genesequence available in GenBank, a pair of primers was designed for developing a SYBRGreenⅠ q uantitative real-time PCR method to detect chicken IL-2gene while the chickenribosomal protein subunit4(RPL4)gene was used as an internal control. To establish thestandard curve, the positive plasmid of each gene served as a standard. The melting curve wasalso analyzed. The results showed that the amplification efficiency of this assay was113%,and the linear range was10-2~10-6with good correlation coefficient of0.9928, as well as thedetection limit reached100copies/μL. The melting curve presented a single peak at(80.2±0.8)℃. There was only4hours needed from extracting RNA to the end of real-timefluorescent quantitative RT-PCR. The developed real-time PCR assay could quickly detectIL-2gene in expansion range with high efficiency, thus providing the basis for quantitativeanalysis of IL-2gene expression.2. This study on IL-2gene expression in the primary immune organs of SPF chickens infected with REV by real-time quantitative RT-PCR. In order to study expression levels ofIL-2gene in SPF chickens infected with reticuloendotheliosis virus(REV),120one-day-oldSPF chicken were randomly divided into2groups. The treatment group chickens was infectedwith REV while the control group was inoculated with normal saline. Six chickens of eachgroup were randomly chosen and killed at day7,14,21,28,35,42and49post infection.thymus, Spleen and bursa were sampled for RNA extraction. SYBR GreenⅠ quantitativereal-time PCR method was applied to compare the relative expression quantity of SPFchicken IL-2gene. We had gotten the following results: IL-2gene expression levels weresignificantly higher (P<0.05) at day7,14,21,28,35,42and49in the thymus, spleen andbursa of Fabricius in SPF chickens from treatment group than those in the control groupexcept that the day21and28in the spleen were not significantly changed (P>0.05).Our studylaid a certain foundation for investigating the mechanism of immunosuppression induced byREV.