Fowl Aviadenovirus (FAdV-11) as the causative agent of a vertical outbreak of inclusion body hepatitis in commercial broiler breeders in Brazil

Abstract

Inclusion body hepatitis (IBH), caused by Fowl Aviadenovirus (FAdV), is a significant disease affecting chickens worldwide. FAdV-11 associated with IBH was identified in 9-day-old commercial broiler breeders in Brazil. The chicks exhibited a sudden increase in daily mortality, accompanied by nonspecific clinical signs, in one house on the farm. The cumulative mortality rate reached 11.13 % by 15 days of age. Macroscopically, the liver was markedly enlarged and pale red with a distinct lobular pattern. Histologically, the liver showed mild to severe multifocal coalescent vacuolar degeneration and necrosis, with hepatocyte nuclei diffusely enlarged and containing large basophilic inclusion bodies. Additionally, the heart exhibited a diffuse, moderate infiltration of lymphocytes and plasma cells, with focal thrombosis in the epicardium. FAdV was detected in liver samples using specific primers for the hexon gene (52 K-fw and 52 K-rv) in a polymerase chain reaction (PCR) assay. Sequencing of the hypervariable region of this gene (Hex L1) for phylogenetic analysis revealed FAdV-D species serotype 11. To our knowledge, this is the first report of FAdV-D serotype 11 as the causative agent of a vertical outbreak of inclusion body hepatitis in broiler breeders in Brazil.

Keywords

• Breeder rearing
• Adenoviridae
• Avian health
• Liver
• IBH
• Basophilic inclusion bodies