As an opportunistic pathogen, Aeromonas veronii can cause hemorrhagic septicemia of various aquatic animals. In our present study, a dominant strain SJ4, isolated from naturally infected mandarin fish (Siniperca chuatsi), was identified as A. veronii according to the morphological, physiological, and biochemical features, as well as molecular identification. Intraperitoneal injection of A. veronii SJ4 into S. chuatsi revealed clinical signs similar to the natural infection, and the median lethal dosage (LD₅₀) of the SJ4 to S. chuatsi in a week was 3.8 × 10⁵ CFU/mL. Histopathological analysis revealed that the isolate SJ4 could cause cell enlargement, obvious hemorrhage, and inflammatory responses in S. chuatsi. Detection of virulence genes showed the isolate SJ4 carried act, fim, flgM, ompA, lip, hly, aer, and eprCAL, and the isolate SJ4 also produce caseinase, dnase, gelatinase, and hemolysin. In addition, the complete genome of A. veronii SJ4 was sequenced, and the size of the genome of A. veronii SJ4 was 4,562,694 bp, within a G + C content of 58.95%, containing 4079 coding genes. Nine hundred ten genes encoding for several virulence factors, such as type III and VI secretion systems, flagella, motility, etc., were determined based on the VFDB database. Besides, 148 antibiotic resistance-related genes in 27 categories related to tetracyclines, fluoroquinolones, aminoglycosides, macrolides, chloramphenicol, and cephalosporins were also annotated. The present results suggested that A. veronii was etiological agent causing the bacterial septicemia of S. chuatsi in this time, as well as provided a valuable base for revealing pathogenesis and resistance mechanism of A. veronii.

维罗尼气单胞菌作为机会致病菌，可引起多种水生动物出血性败血症。本研究从自然感染的鳜鱼( Siniperca chuatsi )中分离得到的优势菌株SJ4，根据形态、生理生化特征以及分子鉴定，鉴定为A. veronii 。腹腔注射A. veronii SJ4至S. chuatsi ，显示出与自然感染相似的临床症状， SJ4对S. chuatsi一周的半数致死剂量(LD _{50 )为3.8 × 10} ⁵  CFU/mL。组织病理学分析表明，分离株SJ4可引起鳅细胞增大、明显出血和炎症反应。毒力基因检测显示，分离株SJ4携带act、fim、flgM、ompA、lip、hly、aer和eprCAL，并且分离株SJ4还产生酪蛋白酶、DNA酶、明胶酶和溶血素。此外，还对维罗尼A. veronii SJ4全基因组进行了测序，维罗尼A. veronii SJ4基因组大小为4,562,694 bp，G+C含量为58.95%，包含4079个编码基因。九百十个基因，编码多种毒力因子，例如III型和VI型分泌系统、鞭毛、运动性等。，是根据VFDB数据库确定的。此外，还注释了四环素类、氟喹诺酮类、氨基糖苷类、大环内酯类、氯霉素类、头孢菌素类等27类148个抗生素耐药相关基因。本研究结果提示维罗尼曲霉是引起本次舒氏沙门氏菌细菌性败血症的病原菌，也为揭示维罗尼曲霉的发病机制和耐药机制提供了有价值的依据。