Choi Yu-Ri, Kim Sang-Won, Shang Ke, Park Jong-Yeol, Zhang Jun-Feng, Jang Hyung-Kwan, Wei Bai, Cha Se-Yeoun, Kang Min
Department of Veterinary Infectious Diseases and Avian Diseases, College of Veterinary Medicine and Center for Poultry Diseases Control, Jeonbuk National University, Iksan, South Korea.
Front Vet Sci. 2022 Feb 24;9:844903. doi: 10.3389/fvets.2022.844903. eCollection 2022.
Avian reoviruses (ARVs) are ubiquitous in domestic poultry with 80% of them being non-pathogenic and they are frequently found in clinically healthy birds. ARVs have also been known to be the etiological agents of viral arthritis (VA), tenosynovitis, myocarditis, runting-stunting syndrome (RSS), and respiratory and enteric disease in chickens. Significant economic losses during the process of poultry husbandry are due, in part, to unmitigated ARV infections throughout the poultry industry. Recently, many isolates shared genetic similarities between those recovered from wild birds and those recovered from poultry. One explanation may be that there is a degree of spillover and spillback of ARVs between the two groups. However, studies on the role of wild birds in the epidemiology and pathogenicity of ARVs are insufficient. Here, we describe the pathogenicity in specific pathogen-free (SPF) chickens of ARV originating from wild birds. The challenge experiment was conducted in six groups including a negative control group, a positive control group (reference strain of S1133), and four groups (A15-157, A18-13, A18-205, A19-106) infected with ARVs from wild birds. The 7-day-old SPF chickens were inoculated with 10TCID ARV to evaluate the clinical signs, changes in weight gain, gross lesions, histological changes, virus replication, and serum antibody levels. The peak of clinical signs was from 3 to 5 days post infection (dpi). In addition, the death of one chicken was found in the group infected with the A18-13 isolate. Reduced body weight was also found in chickens infected with ARVs from wild birds compared to the negative control group. All the ARVs infection groups showed noticeable swelling of the footpad. In addition, ARVs were detected in the bursa, tendon, and hock joint by reverse transcription-polymerase chain reaction (RT-PCR) in all infected groups at 5 and 15 dpi. Histopathological observations revealed acute inflammatory responses on the synovium covering the joint surfaces (arthritis) and tendon sheaths (tenosynovitis), as well as bursa atrophy and lymphocyte depletion. The analysis of the humoral response was performed by ELISA assay, and chickens infected with ARVs showed seroconverted. In conclusion, this study described the typical severe disease of acute VA and tenosynovitis in SPF chickens infected with ARVs derived from wild birds. This study confirmed the pathogenicity of ARVs infection in SPF chickens for the first time, and these results enrich our understanding of the pathogenicity of ARVs derived from wild birds.
禽呼肠孤病毒（ARVs）在家禽中普遍存在，其中80%为非致病性病毒，且常在临床健康的禽类中发现。ARVs也被认为是鸡病毒性关节炎（VA）、腱鞘炎、心肌炎、矮小综合征（RSS）以及呼吸道和肠道疾病的病原体。家禽养殖过程中出现的重大经济损失，部分原因是整个家禽行业中ARV感染未得到缓解。最近，许多分离株在从野生鸟类中分离得到的毒株和从家禽中分离得到的毒株之间具有遗传相似性。一种解释可能是两组之间存在一定程度的ARVs溢出和回溢。然而，关于野生鸟类在ARVs流行病学和致病性中作用的研究并不充分。在此，我们描述了源自野生鸟类的ARV在无特定病原体（SPF）鸡中的致病性。在六个组中进行了攻毒实验，包括一个阴性对照组、一个阳性对照组（S1133参考毒株）以及四个感染源自野生鸟类的ARVs的组（A15 - 157、A18 - 13、A18 - 205、A19 - 106）。对7日龄的SPF鸡接种10TCID的ARV，以评估临床症状、体重增加变化、大体病变、组织学变化、病毒复制和血清抗体水平。临床症状的高峰期出现在感染后3至5天（dpi）。此外，在感染A18 - 13分离株的组中发现有一只鸡死亡。与阴性对照组相比，感染源自野生鸟类的ARVs的鸡体重也有所减轻。所有ARVs感染组均出现明显的脚垫肿胀。此外，在感染后5天和15天，通过逆转录 - 聚合酶链反应（RT - PCR）在所有感染组的法氏囊、肌腱和跗关节中均检测到ARVs。组织病理学观察显示，覆盖关节表面的滑膜（关节炎）和腱鞘（腱鞘炎）出现急性炎症反应，同时伴有法氏囊萎缩和淋巴细胞耗竭。通过ELISA检测进行体液免疫反应分析，感染ARVs的鸡出现了血清转化。总之，本研究描述了感染源自野生鸟类的ARVs的SPF鸡中典型的急性VA和腱鞘炎严重疾病。本研究首次证实了ARVs感染对SPF鸡的致病性，这些结果丰富了我们对源自野生鸟类的ARVs致病性的认识。
