China Animal Husbandry and Veterinary Medicine ›› 2021, Vol. 48 ›› Issue (12): 4628-4640.doi: 10.16431/j.cnki.1671-7236.2021.12.031

• Preventive Veterinary Medicine • Previous Articles     Next Articles

Effects of Different Origins of Infectious Bronchitis Virus on Immune Function in SPF Chicken

MA Zhanbang1,2, XU Liwen1,2, WANG Fangfang1,2, ZHANG Lili1,2, HOU Yutong1,2, HAN Zongxi2, MA Deying1   

  1. 1. College of Animal Science and Technology, Northeast Agricultural University, Harbin 150030, China;
    2. National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, China
  • Received:2021-05-27 Online:2021-12-20 Published:2021-12-02

Abstract: This experiment was conducted to investigate the host innate immune response to different origins of Infectious bronchitis virus (IBV) infection in SPF chicken.One hundred and forty one-day-old SPF White Leghorn chickens were randomly divided into four groups, including three challenge groups and one control group.The challenge groups were inoculated 3 IBVs (including chicken originated IBV virulent strain, chicken originated IBV attenuated strain, and pheasant originated IBV strain) by intranasal eye drops, and the control group was mock inoculated with phosphate-buffered saline (PBS) by the same route.From each of these infected groups five chickens were humanely sacrificed to collected their bursa of Fabricius, kidney and trachea at 12 hour post infection (hpi), 36 hpi, 72 hpi, 7 day post infection (dpi) and 14 dpi.The remaining chickens in each group were continuously observed for clinical symptoms, morbidity and mortality before being killed.The expression of IBV viral load, Toll-like receptors (TLRs) and some cytokines of interleukin (IL) and interferon(IFN) were evaluated by Real-time quantitative PCR.The results showed that SPF chickens infected with chicken origined IBV virulent strain developed clinical sympotoms, the infected SPF chickens showed depression, wing ptosis and other classical symptoms.A total of 7 chickens died during the period of infection (5-10 d), the mortality was 20%.In contrast, for chickens infected with pheasant origined IBV strain, chicken origined IBV attenuated strain and control group, no respiratory clinical signs and no gross lesions were observed during the experimental period.Chickens infected with chicken origined IBV virulent strain demonstrate enlarged kidneys, urate deposits and variegated lesions.Viral loads were detected in bursa of Fabricius, spleen, kidney and trachea of chicken infected with chicken originated IBV virulent.In addition, viral loads were detected in some tissues of the chicken originated IBV attenuated group, but were not detected in the tissues of control and pheasant origined IBV group.The expressions of TLR1, TLR2, TLR3, TLR5, TLR7 and TLR15 genes in bursa of Fabricius were dramatically up-regulated in chicken originated IBV virulent strain group at 72 hpi compared with other groups (P<0.05), IL-6 and IFN-β were released to participate in stronger antiviral immune response at 72 hpi.In chicken originated IBV attenuated strain challenged group, the expressions of TLR2, TLR3, TLR15, TLR21, IL-6 and IL-18 genes in kidney were significantly increased at 7 dpi (P<0.05).The expression of IFN-γ gene in bursa of Fabricius was significantly up-regulated at 36 hpi after infection with pheasant originated IBV strain (P<0.05).In summary, chicken originated IBV virulent strain was highly pathogenic to SPF chicken, the chicken origined IBV virulent strain could dramatically up-regulated the expression of immune-related cytokines in SPF chicken.The above results revealed that the different pathogenicity of IBV virus from different origins to SPF chickens was related to the different immune response.

Key words: Infectious bronchitis virus (IBV); immune mechanism; Toll-like receptor; cytokines

CLC Number: