Changes Of Immunologic Function And IL-2 MRNA Expression In Immune Organs Of Ducks Infected With Avian Influenza Virus

In this study , technology of cell culture, cyto-histochemistry staining and real-time fluorescence quantitative PCR(SYBR GreenⅠ) were used to discover the dynamic changes of the proliferation of T and B lymphocytes to ConA or LPS, the quantity of TANAE+ cells and the expression of IL-2 mRNA in immune organs (thymus, bursa and spleen) of ducks infected with AIV at 21 days old, which were to reveal the mechanism and regulation of immunity of immune organs of ducks infected with AIV at 21 days old. The experiment provided scientific evidence of experiment for the mechanism of morbidity and useful effective prevention in influenza. The results were as follows:1. Compared with controls, the expression of IL-2 mRNA in thymus and bursa of ducks infected with AIV was decreased persistently at 1~21 days post infection (PI) at different degree, and they were both decreased remarkably at 1～14 days PI (p<0.05 or p<0.01); the expression of IL-2 mRNA in spleen was decreased remarkably at 1～9 days PI (p<0.05 or p<0.01).The results revealed that molecular immune function of cytokines in central and peripheral immune organs was inhibited when the expression of IL-2 mRNA in immune organs of ducks infected with AIV was decreased in initial period of infection; and it lead to the cell immunity and the humoral immune function lower than those of control. It indicated that IL-2 played the most important role in anti-virus infection.But, in the end of infective stage, the expression of IL-2 mRNA in immune organs of ducks infected with AIV was close to the controls, and it showed that the expression of IL-2 mRNA in immune organs of ducks infected with AIV was just inhibited for a while.2. The proliferation responses of T-lymphocytes to ConA in thymus and spleen of ducks infected with AIV was remarkably decreased respectively at 3~9 days and 5~9 days PI compared with that of controls (p<0.05 or p<0.01). Compared with controls, The quantity of TANAE+ cells in thymic cortex and medulla was decreased at 1~21 days at different degree, and was remarkable at 3～9 days and 1～9 days respectively PI (p<0.05 or p<0.01). The quantity of TANAE+ cells in bursa of Fabricius lymphaticus folliculus cortex and medulla was decreased remarkably at 5～9 days and 3～9 days respectively PI (p<0.05 or p<0.01), while that of the spleen circum-ellipsoid arterioles and red pulp was also decreased remarkably at 1～7 days and 1～9 days respectively PI (p<0.05 or p<0.01). But with the development of the disease, the quantity of TANAE+ cells in immune organs recovered gradually.The results above could be a important element of leading death of duck infected with AIV at initial period.3. Compared with controls, the proliferation responses of B-lymphocytes to LPS in burse of Fabricius and spleen was decreased remarkably at 3~14 days and 1~9 day respectively PI (p<0.05 or p<0.01).This discoveries showed that the humour function of ducks infected with AIV was inhibited as well.4. The research revealed that the expression of IL-2 mRNA, the proliferation responses of T and B-lymphocytes to ConA or LPS and the quantity of TANAE+ cells in immune organs were all decreased remarkably in initial period of AIV infection. And it indicated that the activation and proliferation of the immunocompetence, especially T and B lymphocyte, were inhibited. The cellular immunity and humoral immune functions were much lower than that of controls, which could be the main reasons of the ducks death in initial period of AIV.infection.