Genotyping and pathogenicity of fowl adenovirus isolated from broiler chickens in Egypt

Abstract

Background Over the past 10 years, inclusion body hepatitis outbreaks, essentially from commercial broiler flocks, have been detected in different geographic regions highlighting the wide distribution of FAdVs around the world resulting in serious economic losses due to increased mortalities as well as poor performance within poultry farms in Assiut province, Egypt. Thus, this study was achieved to detect fowl adenovirus in broiler chicken flocks in Assiut province, Egypt and to recognize the pathogenicity of the isolated virus. Results The phylogeny of the L1 loop of the hexon gene exposed that the isolated virus clustered and belonged to the reference strains serotype D FAdV. The isolated virus is closely related to inclusion body hepatitis (IBH) strains causing extensive economic losses. The pathogenicity study of the virus showed typical macroscopic lesions with 6% mortality; furthermore, histopathological inspection exhibited severe hepatitis and degenerative changes after 5d from infection in the immune system. Conclusion Results in this research support the primary pathogenicity and mortality caused by FADV serotype 2 (IBH) alone without immunosuppressive agents thus robust control measures should be implanted against FAdV to evade the serious economic losses in poultry farms.

Attenuation and molecular characterization of fowl adenovirus 8b propagated in a bioreactor and its immunogenicity, efficacy, and virus shedding in broiler chickens

“…IBH pathogenesis may involve sudden death with no obvious clinical signs [ 6 ]. Surviving chickens may have pale comb and wattle, insensitivity, abnormal position, occasional nervous signs, and reduced growth [ 5 ]. Lesions that are frequently observed include pale, friable, hemorrhagic liver, hemorrhages in the thigh and kidney, and congestion in the ventriculus and spleen [ 6 ].…”

“…Lesions that are frequently observed include pale, friable, hemorrhagic liver, hemorrhages in the thigh and kidney, and congestion in the ventriculus and spleen [ 6 ]. Histopathological changes may include basophilic and/or eosinophilic intranuclear inclusion bodies in the liver and pancreas, inflammatory infiltration in organs [ 5 , 7 ], and lymphoid depletion in the thymus, bursa of Fabricius, and spleen [ 8 ].…”

“…Fowl adenovirus (FAdV) serotype 8b belongs to Group E of the genus aviadenovirus in the family Adenoviridae [1,2] and is an etiologic agent of inclusion body hepatitis (IBH) in broiler chickens that are 3-7 weeks of age and cause mortality of 2%-30% [3][4][5]. IBH pathogenesis may involve sudden death with no obvious clinical signs [6].…”