ACTA VETERINARIA ET ZOOTECHNICA SINICA ›› 2018, Vol. 49 ›› Issue (1): 164-172.doi: 10.11843/j.issn.0366-6964.2018.01.019

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Distribution of Duck Hepatitis A Virus Type 3 in Artificial Infected Ducklings and Analysis of the Relationship between Histopathological Changes and Expression of Cytokines in the Livers

ZHU Yu-dong1,2, WANG Ming-shu1,2,3, CHENG An-chun1,2,3*, ZHU De-kang1,2,3, JIA Ren-yong1,2,3, LIU Ma-feng1,2,3, CHEN Shun1,2,3, ZHAO Xin-xin1,2,3, YANG Qiao1,2,3, WU Ying1,2,3, CHEN Xiao-yue1,3   

  1. 1. Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China;
    2. Sichuan Key Laboratory of Animal Diseases and Human Health, Sichuan Agricultural University, Chengdu 611130, China;
    3. College of Veterinary Medicine, Sichuan Agricultural University, Chengdu 611130, China
  • Received:2017-08-17 Online:2018-01-23 Published:2018-01-23

Abstract:

This experiment was conducted to explore the dynamic distribution of type 3 duck hepatitis A virus (DHAV-3) and the relationship between the induction of histopathological, antiviral cytokines and pro-inflammatory cytokines in 7-day-old ducklings. One week old ducklings were infected with DHAV-3. At 1, 3, 6, 9, 12, 24, 48, 72 and 96 h after infection, 11 tissue samples of blood, liver, spleen, pancreas, kidney, lung, brain, thymus, bursa of Fabricius, Harderian glands and duodenum were collected randomly from three ducklings, and then detected. The virus load was detected by TaqMan real-time one-step RT-PCR and the pathological damage changes of liver was observed by optical microscope, the transcription of anti-viral cytokines (IFN-α, IFN-β and IFN-γ) and pro-inflammatory cytokines (IL-1β, IL-2 and IL-6) in liver were detected by real-time RT-PCR at different time points. The links between these changes were analyzed. The results showed that the virus can be detected in all tissues of 1-week-old ducklings in 1 h after infection. The highest load of virus in tissues was at 24-48 h after infection, except that the highest of blood and pancreas were at 12 h and 96 h after infection respectively. The three organs with the highest viral load were liver, spleen and kidney (1011.15, 1010.37 and 1010.30 copies·g-1). Liver main histopathological changes were vacuoles at 3-12 h, and 24-48 h for the necrotic changes. The transcription of 6 cytokines in the liver reached the highest level at 24-48 h (except for IL-1β at 12 h) after infection. After 48 h of infection, the transcription level of the cytokines decreased with the decrease of the virus content in the liver and was positively correlated with the severity of liver disease. DHAV-3 has extensive tissue tropism in ducklings. Liver, spleen and kidney are the main target organ of virus attack. The cytokines in the liver are highly likely to play an important role in inhibiting viral proliferation and repairing tissue damage.

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