番鸭呼肠孤病毒和H9亚型禽流感病毒共感染对番鸭法氏囊和抗体产生的影响

Influence of co-infection with muscovy duck reovirus and H9 avian influenza virus on bursa and antibody response in muscovy duck

为探讨番鸭呼肠孤病毒(MDRV)和H9亚型禽流感病毒(H9 AIV)共感染对番鸭法氏囊免疫应答能力的影响,本研究将MDRV或/和H9 AIV人工感染8日龄番鸭,观察法氏囊病理组织学变化,检测法氏囊B细胞增殖能力及RE-5 AIV疫苗免疫后抗体变化规律。结果显示:H9 AIV感染组番鸭发病率低(10%),无死亡,法氏囊无病理变化,显著抑制番鸭法氏囊细胞增殖反应;MDRV感染番鸭发病率70%,死亡率40%,生长迟缓,法氏囊病理变化为萎缩,淋巴细胞减少,局部出现范围较小的坏死灶,番鸭法氏囊细胞增殖反应下降;共感染组番鸭发病率100%,死亡率80%,番鸭生长迟缓,法氏囊萎缩和淋巴细胞增殖反应下降程度均比单一病毒感染组严重。病毒感染使番鸭对RE-5 AIV疫苗免疫应答能力明显下降,其共感染组抑制抗体应答程度最严重;共感染组的病毒检出时间早于并且检出率大于单一病毒感染组。表明MDRV与H9 AIV共感染在番鸭免疫应答抑制方面有协同作用。

To investigate the pathogenicity and immune response of muscovy ducks to co-infection of muscovy duck reovirus （MDRV） and H9 subtype avian influnenza virus （AIV）, eight-day old muscovy ducks were divided into 3 groups and artificially infected with MDRV, H9 subtype A1V alone or both, respectively. The pathogenicity of the viruses were evaluated by histopathologic examination of the bursa and proliferation ability of bursa cell, and antibody responses were tested in some ofmuscovy ducks from each group which immunized with H5N1 subtype Re-5 AIV vaccine post the virus infection. The results shown that the morbidity of ducks was low （10%） and no death in AIV infected group, but proliferation ability of bursa cells were obviously suppressed. Ducks infected with MDRV caused 70% morbidity and 40% mortality. Moreover, co-infection was inducedseriously the immune suppression and caused 100% morbidity and 80% mortality. Proliferation ability of bursa cells and immunc responses to Re-5 AIV vaccine was also more obviously suppressed than that of other groups and the virus lasted longer in ducks than that of A1V and MDRV infection alone. Above all, infection with H9 A1V was able to aggravate the immunosuppression due to MDRV infection, therefore, co-infection of MDRV and H9 AIV had synergy effect on depressing immune responses. Our datarevealed that MDRV played an important role in the occurrence and epidemic of waterfowl influenza.