[Immunosuppression effect of co-infection with MDRV and H9 AIV on thymus in muscovy ducks].
OBJECTIVE
To study the immunosuppression effect on the thymus of muscovy ducks after infected with muscovy duck reovirus (MDRV) and H9 influenza virus (AIV).


METHODS
After 8-day-old birds were infected with MDRV or H9 AIV, or both, the morbidity and mortality were totaled, the morphology and ultra-structure of the thymus were observed, proliferation ability of thymus cell were detected and the virus distrubition were detected by RT-PCR.


RESULTS
After H9 AIV infection, The morbidity was low (10%) and without death. No obvious pathological change was observed on the thymus, whereas the proliferation ability of thymus cell was obviously suppressed. After MDRV infection, The birds grew slow, the morbidity was 80% and mortality was 50%. Thymus was atrophy appearing local necrosis and proliferation ability of thymus cell was obviously suppressed. After co-infection with MDRV and H9 AIV, the birds grew even slower growth. The morbidity was 90% and mortality was 70%. The thymus was atrophy appearing the lymphopenia and local necrosis and proliferation ability of thymus cell was also more obviously suppressed than MDRV infection. Virus duration time and detection ratio in co-infection group were more than in AIV and MDRV group.


CONCLUSIONS
H9 AIV could lead to minor immunosuppression and MDRV could cause serious immuno-suppression. H9 AIV could aggravate the immunosuppression of thymus after co-infected with MDRV, so MDRV and H9 AIV infection had synergic effect on immunosuppression of the thymus.
Institute of Animal Husbandry and Veterinary Medicine, Fujian Academy of Agriculture Sciences, Fuzhou 350013, China. lfq1976@163.com
Fengqiang
F
Lin
Chunliang
C
Gao
Shaoying
S
Chen
Xiaoli
X
Zhu
Xiaoxia
X
Cheng
Shao
S
Wang
Shilong
S
Chen
Xi
X
Cai
Zhaolong
Z
Li
Chunquan
C
Ma
Jiarong
J
Zhao
D000818:Animals; D060085:Coinfection / Q000276:immunology* / Q000401:mortality / Q000473:pathology / Q000821:virology; D004372:Ducks; D016867:Immunocompromised Host; D009980:Influenza A virus / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D005585:Influenza in Birds / Q000276:immunology* / Q000401:mortality / Q000473:pathology / Q000821:virology; D018165:Orthoreovirus / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D011201:Poultry Diseases / Q000276:immunology* / Q000401:mortality / Q000473:pathology / Q000821:virology; D012088:Reoviridae Infections / Q000276:immunology* / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D013950:Thymus Gland / Q000276:immunology* / Q000473:pathology / Q000821:virology