番鸭呼肠孤病毒和H9亚型禽流感病毒共感染对番鸭脾脏免疫抑制作用

8日龄番鸭人工感染番鸭呼肠孤病毒（MDRV）或／和H9亚型禽流感病毒（H9AIV），观察其脾脏形态和显微结构变化，检测脾脏细胞增殖功能，探讨病毒感染对番鸭脾脏免疫反应的影响。结果显示，H9AIV感染不引起番鸭发病死亡；番鸭脾脏轻度肿大，病理变化以出血、淋巴细胞坏死为主；显著抑制番鸭脾脏淋巴细胞增殖反应。MDRV单独感染番鸭发病率80％、死亡率50％，对番鸭淋巴细胞增殖反应有抑制作用（差异显著），生长迟缓；脾脏肿大，出现典型坏死病变，细胞凋亡等病理变化。共感染组番鸭发病率100％、死亡率80％，生长迟缓；脾脏异常肿大，白髓区淋巴细胞坏死，数量明显减少甚至消失；坏死灶明显增多，范围增大，坏死灶中淋巴细胞坏死消失后，形成大小不一的空白斑；对番鸭淋巴细胞增殖反应有抑制作用，差异极显著；共感染组在H9AIV病毒检出时间和检出率上均大于AIV组。结果表明，MDRV与H9AIV共感染在番鸭脾脏免疫反应抑制上有协同作用。

Immunosuppression effect of co-infection with MDRV and H9 AIV on spleen in muscovy ducks

. After 8-day-old birds were infected with MDRV（muscovy duck reovirus） or/and H9 AIV,the morphology and ultra-structure of the spleen were observed and proliferation ability of spleen cell was tested in order to access the effect on the immune response in the spleen of muscovy ducks. The results showed that the birds were normal and minor swelling spleen which was mainly hemorrhage and lymphocyte necrosis, but proliferation ability of spleen cell was obviously suppressed after H9 AIV infection. The morbidity was 80% and mortality was 50o//00 ,the birds was the slow growth and thymus atrophy,moreover proliferation ability of thymus cell was also obviously suppressed af- ter MDRV infection. After co-infection with MDRV and H9 AIV,The morbidity was 100% and mortality was 80G, the birds was the slower growth and thymus atrophy, proliferation ability of thymus cell was also more obviously suppressed than that of MDRV infection. Virus detecting time and ratio in co-infection group were more than those of AIV group. Above all, H9 AIV could lead to minor immunosuppression and MDRV could do serious immunosup- pression. H9 AIV could aggravate the immunosuppression of spleen infected with MDRV, so MDRV and H9 AIV in- fection had a synergy effect on depressing immune response.