Zhang Yuxia, Wang Xiaoli, Wang Yongming, Sun Jiazhi, Dong Wenwen, Meng Kai, Li Guiming, Yuan Xiaoyuan
Poultry Institute, Shandong Academy of Agricultural Sciences, Jinan, China.
Shandong Provincial Key Laboratory of Livestock and Poultry Breeding (PKL2024B15), Jinan, China.
Front Microbiol. 2025 Aug 29;16:1652106. doi: 10.3389/fmicb.2025.1652106. eCollection 2025.
() is a significant bacterial pathogen responsible for serositis, perihepatitis, and encephalitis in waterfowl. Although infections have been extensively reported in ducks, geese, and turkeys, cases in chickens are rarely documented. However, recent evidence indicates that it has emerged as a growing threat to chickens in China in recent years.
In this study, we collected 120 clinical samples from 30 chicken farms across Shandong and Henan provinces (2023 to 2024) and conducted a comprehensive etiological investigation involving bacterial isolation, antibiotic susceptibility test and genomics analysis. The pathogenic of two strains (JN01 and BZ), belonging to serotypes 1 and 10, was evaluated.
Our findings revealed as the primary causative agent of the outbreak, with 28 strains successfully isolated. Serotypes 1 and 10 were identified as the predominant epidemic types, while serotypes 7 and 6 appeared sporadically. All isolates exhibited varying degrees of resistance to 15 commonly used antibiotics. Pathogenicity assessment via chicken embryo lethality assay demonstrated that JN01 strain displayed lower virulence than the BZ strain. Experimental infection of specific-pathogen-free (SPF) chickens with a challenge dose of 1 × 10 CFU per chicken successfully reproduced clinical symptoms, with high bacterial loads detected in joint cavities and brains at 10 days post-inoculation. The complete genome of the isolated JN01 was 2,284,590 bp, as determined by third-generation sequencing. Phylogenetic analysis of the whole-genome sequence showed that JN01 is most closely related to strains isolated from ducks within the same clade. Notably, strains from different hosts, including chicken, duck, goose, and tadorna, did not form distinct independent branches but were intermixed throughout the evolutionary tree.
Our findings demonstrated exhibits remarkable host adaptability to chickens. Both the age-dependent susceptibility and clinical manifestations in boilers are essentially consistent with those observed in ducks. The serotypes prevalent in chicken flocks share both similarities and differences with those in duck flocks. Notably, its lethality to chickens is significantly lower than that to ducks. These findings enhance our understanding of the epidemiology and pathogenicity of from chicken, providing a scientific foundation for targeted disease prevention and control measures.
（）是一种重要的细菌病原体，可导致水禽发生浆膜炎、肝周炎和脑炎。虽然在鸭、鹅和火鸡中已广泛报道有感染情况，但鸡感染的病例鲜有记录。然而，最近的证据表明，近年来它已成为中国鸡群中日益严重的威胁。
在本研究中，我们从山东和河南的30个养鸡场（2023年至2024年）收集了120份临床样本，并进行了全面的病因调查，包括细菌分离、药敏试验和基因组分析。评估了两株属于血清型1和10的菌株（JN01和BZ）的致病性。
我们的研究结果表明（）是此次疫情的主要病原体，成功分离出28株菌株。血清型1和10被确定为主要流行类型，而血清型7和6偶有出现。所有分离株对15种常用抗生素均表现出不同程度的耐药性。通过鸡胚致死试验进行的致病性评估表明，JN01菌株的毒力低于BZ菌株。用每只鸡1×10 CFU的攻击剂量对无特定病原体（SPF）鸡进行实验性感染，成功再现了临床症状，接种后10天在关节腔和脑中检测到高细菌载量。通过第三代测序确定，分离出的JN01的完整基因组为2,284,590 bp。对全基因组序列的系统发育分析表明，JN01与同一进化枝中从鸭分离出的菌株关系最为密切。值得注意的是，来自不同宿主（包括鸡、鸭、鹅和麻鸭）的菌株并未形成明显的独立分支，而是在整个进化树中相互混杂。
我们的研究结果表明（）对鸡具有显著的宿主适应性。肉仔鸡中与年龄相关的易感性和临床表现与鸭中观察到的基本一致。鸡群中流行的血清型与鸭群中的血清型既有相似之处也有不同之处。值得注意的是，它对鸡的致死率明显低于对鸭的致死率。这些发现加深了我们对鸡源（）的流行病学和致病性的理解，为针对性的疾病预防和控制措施提供了科学依据。
