College of Life Science and Engineering, Foshan University, 528531, Foshan, China.
Key Lab of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, China.
Sci Rep. 2019 May 10;9(1):7231. doi: 10.1038/s41598-019-43660-2.
Avian influenza virus subtype H9N2 is identified in chickens with respiratory disease while Bacillus cereus (B. cereus) has been frequently isolated from chicken feed in China. However, the roles of co-infection with these two pathogens remain unclear. In the present study, SPF chicks were intragastrically administered with 10 CFU/mL of B. cereus for 7 days and then inoculated intranasally with 100 EID of H9N2 three days later. Alternatively, chickens were initially inoculated with H9N2 and then with B. cereus for one week. Post administration, typical respiratory distress persisted for 5 days in both co-infection groups. Gizzard erosions developed in the groups B. cereus/H9N2 and B. cereus group on 7 day while in group H9N2/B. cereus on 14 day. More importantly, both air-sac lesions and lung damage increased significantly in the co-infection group. Significant inflammatory changes were observed in the B. cereus group from day 7 to day 21. Moreover, higher loads of H9N2 virus were found in the co-infected groups than in the H9N2 group. Newcastle Disease Virus (NDV) specific antibodies were decreased significantly in the H9N2/B. cereus group compared to the B. cereus and the B. cereus/H9N2 groups. Nonspecific IgA titers were reduced significantly in the B. cereus group and the H9N2/B. cereus group compared to the control group. In addition to this, lower lymphocyte proliferation was found in the con-infection groups and the H9N2 group. Hence, feed-borne B. cereus contamination potentially exacerbates gizzard ulceration and aggravates H9N2-induced respiratory distress by inhibiting antibody-mediated immunity and pathogen clearance. Thus controlling the B. cereus contamination in poultry feed is immediately needed.
鸡感染 H9N2 亚型禽流感病毒和食源性蜡样芽胞杆菌（Bacillus cereus，B. cereus）是常见的鸡呼吸道疾病的病因，但这两种病原体共同感染时的作用尚不清楚。本研究中，SPF 雏鸡连续 7 天每天经口灌胃 10CFU/mL 的 B. cereus 后，3 天后经鼻腔接种 100 EID 的 H9N2 病毒，或先滴鼻接种 H9N2 病毒，1 周后再经口灌胃 B. cereus。攻毒后，两种共同感染组雏鸡均出现典型的呼吸窘迫症状，持续 5 天。B. cereus/H9N2 组和 B. cereus 组于攻毒后第 7 天出现肌胃糜烂，H9N2/B. cereus 组于第 14 天出现肌胃糜烂。更重要的是，共同感染组气囊病变和肺部损伤明显增加。B. cereus 组从第 7 天到第 21 天观察到明显的炎症变化。此外，与单独感染 H9N2 病毒的雏鸡相比，共同感染组雏鸡的 H9N2 病毒载量更高。与 B. cereus 组和 B. cereus/H9N2 组相比，H9N2/B. cereus 组雏鸡的新城疫病毒（Newcastle Disease Virus，NDV）特异性抗体显著降低。与对照组相比，B. cereus 组和 H9N2/B. cereus 组的非特异性 IgA 滴度显著降低。此外，共同感染组和 H9N2 组的淋巴细胞增殖能力降低。因此，食源性 B. cereus 污染可能通过抑制抗体介导的免疫和病原体清除来加重肌胃溃疡和 H9N2 诱导的呼吸窘迫。因此，立即需要控制家禽饲料中的 B. cereus 污染。
