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Gizzard erosion and ulceration syndrome (GEUS) is caused by a fowl adenovirus serotype 1 (FAdV-1) and was first reported in laying hens in Japan in 1993. This syndrome has emerged as an epizootic in Morocco since 2014, causing significant economic losses for the poultry industry, but no involvement of a FAdV has been confirmed. Thus, the objective of this work was to assess GEUS cases that occurred in the country and to determine the role of FAdVs in their occurrence. Investigations were based on a retrospective reassessment of tissue sections and paraffin blocks of gizzards and livers from GEUS cases between 2014 and 2021 coupled with a prospective search of cases in 2022. Gizzards and livers were fixed in 10% neutral buffered formalin for histopathologic examinations according to standard methods and stored at -20 C for molecular analysis. After deparaffinizing, 10-µm-thick tissue sections along with fresh organs were subjected to DNA extraction using a commercial kit. A primer pair specific for the Hexon gene of FAdVs was used in conventional PCR; in contrast, for real-time PCR, a primer pair targeting the 52K gene was employed. In total, 24 flock cases with characteristic GEUS were assessed between 2014 and 2022. They were nine broiler cases aged between 11 and 39 days, 11 layer cases with an age between 17 and 29 wk, two cases in meat-type breeders aged 10 and 27 wk, and two flock cases of turkey poults aged 22 and 23 days. In most cases, microscopic lesions were consistent with an ulcerative and lymphoplasmocytic ventriculitis, and pathognomonic viral intranuclear inclusion bodies within degenerate epithelial cells were identified in four broiler flock cases, four layer cases, and one case in breeders and hence were highly suggestive of a FAdV infection. Among these nine cases that were positive at the histopathologic examination, six cases were found to be FAdV-PCR positive; another four cases were negative to histology but FAdV-PCR positive. Furthermore, a sequencing analysis was conducted, providing the initial evidence of the implication of FAdV-1 from species A as the cause of GEUS in Moroccan poultry. Additionally, a phylogenetic analysis was executed to facilitate a comparison between the strains investigated in this study and those identified in diverse geographic regions and across various time periods.

The present study was conducted in order to isolate, identify and characterize fowl aviadenovirus associated with inclusion body hepatitis (IBH) in three poultry farms (two of broiler chickens and one of breeder broiler chickens) in Morocco during 2015. Liver samples collected from affected three poultry farms were examined by histopathological examination. Tissue samples showing necrosis of hepatocytes associated with basophilic intranuclear inclusion bodies were homogenized and submitted to FAdV isolation in chicken embryo fibroblast (CEF) cell cultures and in SPF embryonated eggs. The cytopathic effect (CPE) was observed in the second passage with swelling and rounding of infected cells. The inoculated embryos were hemorrhagic and showed hepatitis with the presence of basophilic intra-nuclear inclusion bodies within hepatocytes. The presence of the virus was confirmed by conventional polymerase chain reaction based on hexon gene from all investigated samples. Moreover, phylogenetic analysis of the hexon gene revealed that FAdVs isolated from different affected poultry belonged to FAdV 11 serotype of the D genotype group. This work is the first isolation in cell culture and SPF embryonated eggs of FAdV from Moroccan broilers and breeder broiler chickens with IBH., Competing Interests: We confirm that no competing interests exist. The funding from Biopharma does not alter our adherence to PLOS ONE policies on sharing data and materials.