Regulation Role Of Treg Cells In Immune Response Induced By Brucella Vaccine M5-90

Brucellosis is recognized as one of the world’s major zoonoses, caused by Brucella. It can cause abortion, sterility and remittent fever. It is prevalent in170countries and regions all lover the world. In China, it is especially serious in Xinjiang and Qinghai, threating livestock production and the health of human beings. Brucella, typically intracellular, mainly causes cellular immunity, and T lymphocytes play a vital role. CD4+CD25+T (Treg) cells, at present the most important immune inhibitory control cells, are found immunological unresponsiveness and immune suppression,maintaining the body’s immune stability and tolerance. Low quantity and functional disorders of Tregs can lead to a variety of autoimmune disease. In addition, Tregs also play an important role in some severe inflammatory disease and immune response. Foxp3gene has a great influence on the development and transformation of Treg. The further research of biological characteristics of Tregs will help us to the understanding of the mechanisms of clinical diseases and new treatment strategy formulation. Now whether Treg cells involved in the immune response regulation of sheep towards Brucella M5-90is unclear. In order to investigate the role of Tregs in the sheep immune response induced by Brucella M5-90, this project mainly carried out the following research:1, Study on CD4+CD25+regulatory T cells and CD4+, CD8+, CD25+T lymphocyte subgroup in peripheral blood of sheep inoculated with Brucella vaccine M5-90:Sheep were vaccinated three times at10-days interval using Brucella M5-90. The blood samples from jugular vein were detected Treg cells and T cell subsets within two hours. The result indicated that both CD4+(40.44%)and CD8+T(28.79%) reached the highest level on day20and stopped to reduce.Treg was consistently increased, and on day30, it was the highest at9.07%. CD4+/CD8+was always at the level of1.49. Research results suggested a rise in Treg cells which inhibited the proliferation of CD4+T and CD8+T lymphocyte, and maintained the balance of the body reaction between Th1/Th2cells;2-, Research on the detection of IL-1β、IL-6and antibody in peripheral blood of sheep inoculated with Brucella vaccine M5-90:The serum was separated and Brucella antibody level was detected by plate agglutination and test tube agglutination. The positive rate of antibody was100%on day10, day20and day30. During the whole process,it was positive from day10,and reached the highest level on day20after which it began to reduce; Relevant cell factor detection method was established for Elisa detection toward IL-1β and IL-6.IL-1β was significant on day30, but IL-6was not significant.This indicated Treg cells participated in the humoral immune and cellular immune response towards Brucella M5-90.In addition, IL-1β may promote the proliferation of Treg cells. 3、Research on the detection of Foxp3gene in Treg cell after vaccination of Brucella M5-90in sheep:PBMCs were isolated and RNA of PBMC was extracted. The sequences of Foxp3and sheep β-actin were searched from Gen Bank, and then the synthesis of primers were completed. RT-PCR technology was used to analysis. Expression of Foxp3gene was a positive correlation with Tregs.It suggested Foxp3prompt the development and transformation of Treg cells and help the immune suppression function of Treg cells.This research indicated that Tregs participated in the immune regulation of the sheep towards Brucella vaccine M5-90and maintained the stability of CD4+/CD8+, and balanced the cell reaction between Thl and Th2; It also indicated Foxp3participated in the growth and transformation of Tregs, helped to realize the immune suppression function.This would favor to the further research of immune mechanism of Brucellosis.