Studies On The Cellular Immunity Function Of The Muscovy Duck Infected With MDRV And H9AIV Simultaneously

Waterfowls are susceptible to Muscovy duck reovirus disease which has been prevailed in some areas in China since1997, seriously affecting the development of waterfowl industry in the areas. To reveal the immuno-suppression mechanisms of waterfowls challenged by Muscovy duck reovirus (MDRV) and avian influenza virus (H9AIV) individually and simultaneously, Muscovy ducklings at eight days old were selected for this study. Stimulation indexes of T lymphocyte, ratio of T lymphocyte, immune organ development and cytotoxic ability of T lymphocyte were determined. The results are as follows:(1) Stimulation indexes of T lymphocyte in peripheral blood, thymus and spleen of the Muscovy ducklings were determined by MTT method after the Muscovy ducklings were challenged at1st day,3rd day,5th day,7th day,10th day and14th day. The results show that stimulation indexes of T lymphocyte in peripheral blood, thymus and spleen of all challenged groups are significantly lower than that of control group, and the stimulation indexes of T lymphocyte of group challenged with MDRV and H9AIV simultaneously are lower than that of groups challenged with MDRV and H9AIV individually. The proliferation functions of T lymphocyte in peripheral blood, thymus and spleen of all challenged groups are inhibited by MDRV and H9AIV individually and simultaneously and the immune inhibitions are the most remarkable in the group challenged with MDRV and H9AIV simultaneously.(2) Ratio of T lymphocyte in peripheral blood was measured by Flow cytometry after the Muscovy ducklings were challenged at1st day,4th day,7th day,11th day,14th day,21st day and30th day.. The results show that the rates of T lymphocyte of all challenged groups are significantly lower than control group and are gradually increased after the21st day. Significant difference is still maintained between control group and challenged group with MDRV and H9AIV simultaneously, but no significant differences are observed between control group and challenged group with MDRV and H9AIV individually after the30th day.(3) The incidence of death, immune organ development and immune organ indexes of Muscovy ducklings were recorded and determined. The results show that the incidence and mortality are significantly higher in the group challenged with MDRV and H9AIV simultaneously than the group challenged with MDRV and H9AIV individually. In the group challenged with MDRV individually and the group challenged with MDRV and H9AIV simultaneously, at the7thday and the14th day, thymus and bursa are atrophy, indexes of thymus and bursa are decreased; spleens are enlarged and necrotic, index of spleen is increased. Immune organ development and immune organ indexes of Muscovy ducklings are not impacted by challenge with H9AFV individually.(4) Lymphocytes were separated by lymphocyte separation medium. Lymph-mononuclear cells in peripheral blood, spleen and thymus were determined by routine white blood cell count method after the Muscovy ducklings were challenged at7th and14th day. The results show that in the group challenged with MDRV and the group challenged with MDRV and H9AIV simultaneously, the number of lymph-mononuclear cells is smaller than that of control group and the group challenged with H9AIV (significant difference).But the number of lymph-mononuclear cells is not significant difference between AIV challenged group and control group. The number of lymph-mononuclear cells is impacted by challenge with MDRV individually. And the number of lymph-mononuclear cells is the smallest in the group challenged with MDRV and H9AIV simultaneously.(5) Cytotoxic ability of T lymphocyte in peripheral blood was determined by MTT method and cytotoxicity function of CTL was analyzed after the Muscovy ducklings were challenged at1st day,7th day,14th day,21st day and28th day. The results show that cytotoxic ability of T lymphocyte in peripheral blood is not significant difference between ATV challenged group and control group during whole experiment, but differences are significant between MDRV challenged group and control group after14th day, and there are significant differences between MDRV-H9AIV challenged group and control group from7th day to28th day.The results indicate that both MDRV and H9AIV can influence stimulation indexes of T lymphocyte, proliferation functions of T lymphocyte, the rates of T lymphocyte, incidence and mortality of Muscovy ducklings. Immune organ development, immune organ indexes and cytotoxic ability of T lymphocyte are disturbed by challenge of MDRV individually and by challenge of MDRV-H9AIV simultaneously, severe disturbances are observed in the group of challenge of MDRV-H9AIV simultaneously, but they are not impacted by challenge with H9AIV individually.