Elevated level of renal xanthine oxidase mRNA transcription after nephropathogenic infectious bronchitis virus infection in growing layers

Lin, Huayuan; Huang, Qiqi; Guo, Xiaoquan; Liu, Ping; Liu, Weilian; Zou, Yuelong; Zhu, Shuliang; Deng, Guangfu; Kuang, Jun; Zhang, Caiying; Cao, Huabin; Hu, Guoliang

The nephropathogenic infectious bronchitis virus was preserved by the clinical veterinary science laboratory of Jiangxi Agricultural University. The virus was propagated in 10-day-old specific pathogen-free (SPF) embryonating chicken eggs. Briefly, serial 10-fold dilutions (10 −1 to 10 −10 ) of the virus were prepared in sterile physiological saline and used to infect SPF embryonating chicken eggs. The 10 −5 embryo median lethal dose 50 was calculated according to the formula of Reed and Muench [26] . Each chicken in the infected group was intranasally inoculated with 0.2 mL of 10 −5 median embryo infectious doses of nephropathogenic infectious bronchitis virus at 35 days of age. Chickens in the control group were intranasally inoculated with 0.2 mL of sterile physiological saline as virus-free controls. Chickens were examined daily for signs of infection after inoculation. Clinical signs were observed at 7 days post-inoculation (dpi) in most infected chickens. We then collected blood and organ samples at 8, 15 and 22 dpi (12 blood samples were collected from each group every time). Sera were separated by centrifugation for 5 min at 2,500 × g, then stored at −20 o C for analysis. Organ samples (kidney) were individually collected into the freezing tubes and snap frozen in liquid nitrogen. Subsequently, snap-frozen organs were stored at −80 o C immediately until RNA extraction. All experiments were conducted after institutional approval of the animal Care and Use Committee of Jiangxi Agricultural University.