Abstract
Hydropericardium hepatitis syndrome (HHS) is a lethal disease caused by Fowl adenovirus serotype 4(FAdV-4) that mainly infects 3- to 6-week-old broiler chicks. In 2015, an infectious disease characterized similar symptom to HHS in broilers outbroke in commercial duck flocks in Shandong province. FAdV-4 was isolated from naturally infected ducks and determined by polymerase chain reaction (PCR) amplification and DNA sequence analysis. In order to investigate the effect of FAdV-4 infection on muscovy ducks, we determined and characterized the FAdV-4 Isolate, and assessed its pathogenicity. In this study, HHS was respectively reproduced in 5-week-old muscovy duck by intramuscular injection and intranasal inoculation of allantoic fluid containing FAdV-4, ducks in the negative control group were inoculated with allantoic fluids of healthy duck embryos in the same manner. Clinical symptoms, gross and microscopic lesions, cytokines and antibodies, blood biochemical indices were detected and recorded for 12 days after infection. Typical hydropericardium and hepatitis was observed in experimental muscovy duck in the 3rd day post-inoculation (dpi). FAdV-4 can be replicated in tissues and cause pathological damage, especially in the liver and immune organs. Most of the immune-related cytokines and antibodies levels are up-regulated and then decreased, which may be caused by the initial infection and the normal immune response, later the virus caused the immunosuppression and led to the decrease of levels. To the best of our knowledge, this is the first systematic trial of the pathogenicity of FAdV-4 in muscovy ducks mainly based on the serological test, which will provide new insights into the study of the disease.
Highlights
Fowl adenoviruses (FAdVs) is non-enveloped double stranded DNA-viruses, which was grouped into 5 species (FAdV-A to FAdV-E) with 12 serotypes (FAdV-1 to 12) (Hess, 2000)
Hydropericardium hepatitis syndrome caused by FAdV-4 was first detected and isolated from broilers in Eastern China during 2012 to 2013 (Zhao et al, 2015) and this disease was first detected from Cherry Valley ducks at 2015 (Chen et al, 2017)
Hydropericardium hepatitis syndrome (HHS) has resulted in enormous economic loss for poultry industry (Asthana et al, 2013)
Summary
Fowl adenoviruses (FAdVs) is non-enveloped double stranded DNA-viruses, which was grouped into 5 species (FAdV-A to FAdV-E) with 12 serotypes (FAdV-1 to 12) (Hess, 2000). The Pathogenicity of FAdV-4 Strain in Muscovy Ducks of 30–70%. Outbreaks of HHS caused by FAdV-4, and the disease have occurred all over the world (Mase et al, 2010; Schachner et al, 2018). Previous study indicated that FAdV-4 isolates can cause HHS and significant mortality in broilers and goose (Toro et al, 2000; Ivanics et al, 2010). In 2015, an infectious disease, which mainly infected 25–40 day-old ducklings, characterized similar symptom to HHS, outbroke in commercial duck flocks in Shandong province. According to lately published report, this disease was confirmed to be caused by FAdV-4 (Chen et al, 2017). One FAdV-4 strain which isolated from recent outbreaks was characterized by phylogenetic assays and pathogenic analysis. 4-week-old ducks were infected with FAdV-4 by different routes to investigate the effect of FAdV-4 on muscovy ducks
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