Molecular characterization of aviadenovirus serotypes and pathogenicity of the identified adenovirus in broiler chickens

Inclusion body hepatitis (IBH) is an economically significant viral disease that primarily affects broiler chickens. At least 12 different aviadeno-virus serotypes are responsible for causing IBH. This study aimed to use polymerase chain reaction (PCR) and phylogenetic analysis to characterize fowl adeno-virus isolates that were in circulation from 2019 to 2021 and investigate the pathogenicity of the isolated strains in commercial broiler chickens. Suspected liver samples were molecularly identified using hexon gene targeting by PCR, and viruses were isolated using chick embryo liver cell culture. For serotype identifi-cation, the fowl adenovirus-positive samples were subjected to hexon gene sequencing and phylogenetic analysis. The pathogenicity of two isolates was tested in commercial chickens via the oral route. The phylo-genetic analysis of the hexon gene showed that the isolated viruses clustered with serotype 8a species E. On testing the pathogenicity of the isolates based on necropsy and histopathological examination, no mor-tality was observed; however, lesions were observed in the liver, kidney, heart, pancreas, bursa, and lung specimens with intermittent virus shedding at differ-ent time points throughout the experimental period. Further research on the likelihood of vaccine produc-tion is warranted to limit disease-related losses.

Automated summary

This study characterized fowl adenovirus isolates in circulation from 2019 to 2021 using PCR and phylogenetic analysis, and investigated their pathogenicity in commercial broiler chickens. The isolated viruses clustered with serotype 8a species E, and caused lesions in various organs during the experimental period.