Viral nervous necrosis (VNN) is one of the most important problems in sea bass culture. Although there have been many studies on detection and molecular characterization of betanodavirus, the causative agent of VNN, there has been little focus on understanding its prevalence to create epidemiological maps. The purpose of this study was to investigate the prevalence of betanodavirus in active sea bass hatcheries and on selected farms in Turkey by RT-qPCR. A total of 2460 samples, including fertilized eggs, prelarvae, postlarvae, fry, and fingerlings, were collected from 16 hatcheries to cover all production stages. A total of 600 sea bass were also collected from 20 farms. Betanodavirus was detected in one hatchery (1/16) in fingerling-sized sea bass, and the prevalence of betanodavirus at the hatchery level was calculated to be 6.25%. Betanodavirus was also detected on one farm (1/20) in fingerling-sized sea bass, and the prevalence of betanodavirus at the farm level was calculated to be 5%. Virus isolation initially could not be achieved in E-11 cells, but later, SSN-1 cells were used successfully. Partial genome sequence analysis of the RNA1 and RNA2 segments of the viruses revealed that they were of the red-spotted grouper nervous necrosis virus genotype, which is endemic in the Mediterranean basin. The absence of mortality related to VNN in the hatcheries and on the farms, the healthy appearance of the sea bass, the low viral load detected, and the results of retrospective epidemiological studies indicated that the infection was subclinical. Not detecting betanodavirus in other age groups where biosecurity was implemented indicates that there was no active infection. In light of these findings, it can be concluded that there was no betanodavirus circulating in hatcheries, and the virus might have been of seawater origin.

病毒性神经坏死（VNN）是鲈鱼养殖中最重要的问题之一。尽管对 VNN 的病原体 Betaodavirus 的检测和分子特征进行了许多研究，但很少关注了解其流行情况以创建流行病学图。本研究的目的是通过 RT-qPCR 调查活跃的鲈鱼孵化场和土耳其选定养殖场中贝诺达病毒的流行情况。从 16 个孵化场共采集了 2460 份样本，包括受精卵、前期幼体、后期幼体、鱼苗和鱼种，涵盖所有生产阶段。还从 20 个农场收集了 600 条鲈鱼。贝诺达病毒在一个孵化场 (1/16) 的鱼种大小的鲈鱼中检测到，计算得出孵化场的贝诺达病毒流行率为 6.25%。在一个养殖场（1/20）的鱼种大小的鲈鱼中也检测到了贝诺达病毒，计算得出养殖场一级贝诺达病毒的流行率为 5%。最初无法在 E-11 细胞中实现病毒分离，但后来成功使用了 SSN-1 细胞。病毒的 RNA1 和 RNA2 片段的部分基因组序列分析表明，它们属于地中海盆地流行的红斑石斑鱼神经坏死病毒基因型。孵化场和养殖场中没有与 VNN 相关的死亡率、鲈鱼的健康外观、检测到的低病毒载量以及回顾性流行病学研究结果表明感染是亚临床的。在实施生物安全措施的其他年龄组中未检测到 Betaodavirus 表明没有活动性感染。