Mirzazadeh Amin, Grafl Beatrice, Abbasnia Mohammad, Emadi-Jamali Sobhan, Abdi-Hachesoo Bahman, Schachner Anna, Hess Michael
Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
Clinic for Poultry and Fish Medicine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria.
Front Vet Sci. 2021 Feb 1;8:635186. doi: 10.3389/fvets.2021.635186. eCollection 2021.
Adenoviral gizzard erosion (AGE) in broilers is an emerging infectious disease with negative impact on flock productivity. Despite of known primary etiological role of fowl adenovirus serotype 1 (FAdV-1) in AGE, there are a limited number of field reports worldwide, possibly because the disease is less noticeable and clinically difficult to assess. The present study documents an outbreak of AGE in 16-day-old broiler chickens on a farm in the north of Iran and the reproduction of the disease in an experimental setting. In the field, a sudden onset of mortality was noticed in affected broilers resulting in 6% total mortality and decreased weight gain leading to approximately 1-week delay to reach the target slaughter weight. Necropsy findings in dead broilers revealed black colored content in crop, proventriculus and gizzard together with severe gizzard erosions characterized by multiple black-brown areas of variable size in the koilin layer and mucosal inflammation. Microscopic examination revealed necrotizing ventriculitis marked with severe dissociation of koilin layer and degeneration of glandular epithelium with infiltration of mononuclear inflammatory cells. FAdV-1 was isolated from affected gizzards. Phylogenetic analysis of the hexon loop-1 (L1) sequence of the isolated virus showed 100% identity with pathogenic FAdV-1 strains previously reported from broiler chickens with AGE. Subsequently, an study infecting day-old commercial layer chickens with the field isolate demonstrated characteristic lesions and histopathological changes of AGE together with decreased weight gain in the infected birds. For the first time, the progress of a natural outbreak of AGE in Iran is described and experimental reproduction of the disease is demonstrated. The findings highlight the economic impact of the disease for regional poultry production due to mortality and impaired weight gain of the affected broilers.
肉鸡腺病毒引起的肌胃糜烂（AGE）是一种新出现的传染病，对鸡群生产性能有负面影响。尽管已知禽腺病毒1型（FAdV-1）在AGE中起主要病原作用，但全球范围内的现场报告数量有限，可能是因为该病不太明显且临床上难以评估。本研究记录了伊朗北部一个农场16日龄肉鸡发生的AGE疫情，以及在实验环境中该病的再现情况。在现场，受影响的肉鸡突然出现死亡，总死亡率达6%，体重增加减少，导致达到目标屠宰体重的时间延迟约1周。对死亡肉鸡的尸检结果显示，嗉囊、腺胃和肌胃中有黑色内容物，同时肌胃有严重糜烂，表现为角质膜层有多个大小不一的黑褐色区域以及黏膜炎症。显微镜检查显示坏死性肌胃炎，其特征为角质膜层严重分离、腺上皮变性以及单核炎性细胞浸润。从受影响的肌胃中分离出了FAdV-1。对分离病毒的六邻体环1（L1）序列进行系统发育分析，结果显示与先前报道的患有AGE的肉鸡的致病性FAdV-1菌株具有100%的同一性。随后，一项用现场分离株感染1日龄商品蛋鸡的研究表明，感染鸡出现了AGE的特征性病变和组织病理学变化，同时体重增加减少。本研究首次描述了伊朗AGE自然疫情的进展情况，并证明了该病的实验性再现。这些发现突出了该病对区域家禽生产的经济影响，原因是受影响肉鸡的死亡和体重增加受损。
