Pathogenicity and Complete Genome Characterization of Fowl Adenoviruses Isolated from Chickens Associated with Inclusion Body Hepatitis and Hydropericardium Syndrome in China.

Jing Zhao,Guo-Zhong Zhang,Yan-Xin Hu,Qi Zhong,Ye Zhao,Joanne Devlin

doi:10.1371/journal.pone.0133073

Abstract

In this study, we determined and genetically characterized three fowl adenoviruses isolated from chickens with inclusion body hepatitis (IBH) and hydropericardium syndrome (HPS) in China and assessed their pathogenicity. The full genome of HBQ12, BJH13 and JSJ13 was found to be 44,081, 43,966 and 43,756 nucleotides long, respectively. Sequence alignment and phylogenetic analysis revealed that strain HBQ12 and BJH13 were clustered together belonging to fowl adenoviruses D species and serotyped as FAdV-11, whereas strain JSJ13 was classified into fowl adenoviruses C species and serotyped as FAdV-4. To our knowledge, this is the first report of FAdV-4 strain circulating in China. The pathogenicity test showed that mortality for chickens infected with HBQ12 and JSJ13 within 21 days post infection (dpi) was 8.6% and 28.6%, respectively. Necropsy displayed mild or severe hepatitis and hydropericardium at 3 and 5 dpi as well as dead chickens. Viral DNA was detected in almost all tissues sampled from dead chickens. These results revealed that fowl adenovirus strains HBQ12 and JSJ13 are capable of causing IBH and HPS in chickens, indicating that preventive measures against FAdV infection on poultry farms should be implemented in China.

Highlights

Adenoviruses (AdVs) are non-enveloped double stranded DNA-viruses, which belong to the family Adenoviridae
Most cases were observed in broilers of 3 to 5 weeks of age, and occasionally in layers and breeder pullets aged 10 to 20 weeks. Mortality reported during these outbreaks varied from a slight increase to over 30% in severe cases and fowl adenoviruses (FAdVs) were isolated from all the cases, but the molecular and pathogenic characterization of these viruses involved in inclusion body hepatitis (IBH) or hydropericardium syndrome (HPS) outbreaks were still unknown
In recent years, increasing clinical cases of FAdV infections have been concerned and many FAdV strains related to IBH, HPS or gizzard erosions (GE) have been isolated from most cases in many countries [7, 15,16,17]

Summary

Introduction

Adenoviruses (AdVs) are non-enveloped double stranded DNA-viruses, which belong to the family Adenoviridae. Chickens can be infected by fowl adenoviruses (FAdVs), belonging to the genus Aviadenovirus, egg drop syndrome (EDS) virus (duck adenovirus A, genus Atadenovirus) and turkey hemorrhagic enteritis (HE) virus (turkey adenovirus A, genus Siadenovirus). The most notable diseases associated with FAdVs-infection in chicken are the inclusion body hepatitis (IBH), the hydropericardium syndrome (HPS) and the gizzard erosions (GE) [4,5,6]. Classical IBH affects mostly 3–5 weeks old chickens and is characterized by mortality approaching 10% and hepatic necrosis with microscopic eosinophilic or basophilic intranuclear inclusion bodies in hepatocytes [7, 8]. Most HPS are caused by FAdV serotype 4 (FAdV-4), characterized by accumulation of transparent or straw-colored fluid in the pericardial sac, nephritis, and hepatitis with a high mortality of 30–70% [9, 10]. GE is induced by several serotypes of FAdVs and frequently found in slaughtered broiler chickens [11,12,13]

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