Vol.:(0123456789) 1 3 Archives of Virology (2019) 164:105–116 https://doi.org/10.1007/s00705-018-4054-9 ORIGINAL ARTICLE Isolation, identifcation, and classifcation of a novel rhabdovirus from diseased Chinese rice‑feld eels (Monopterus albus) Wenzhi Liu 1  · Yuding Fan 1  · Zhong Li 1  · Jianqing Zhao 1  · Yong Zhou 1  · Nan Jiang 1  · Jia Zeng 1,2  · Kenneth Cain 3  · Lingbing Zeng 1 Received: 7 June 2018 / Accepted: 23 September 2018 / Published online: 4 October 2018 © Springer-Verlag GmbH Austria, part of Springer Nature 2018 Abstract In 2017, a clinical disease outbreak resulted in substantial mortality of adults and larvae of cultured Chinese rice-feld eels (Monopterus albus) on a farm in Hubei, Central China. A rhabdovirus was isolated from moribund specimens, and typical clinical symptoms associated with an outbreak included an enlarged and swollen head. This difered from previous observa- tions. Histological changes included necrosis and cavities of various sizes within the brain and kidney. Homogenized tissues of diseased Chinese rice-feld eels were screened for viral isolation using six diferent fsh cell lines. A rhabdovirus was isolated following observation of cytopathic efect (CPE) in a gibel carp brain (GiCB) cell line and confrmed by RT-PCR. Electron microscopy showed large numbers of rhabdovirus-shaped particles in the cytoplasm of the brain cells of the diseased Chinese rice-feld eels and in the infected GiCB cell line. This virus has been named “Chinese rice-feld eel rhabdovirus” (CrERV), and the complete nucleotide sequence of CrERV was cloned. This rhabdovirus is composed of 11,545 nucleo- tides with the following genomic organization: 3′-N-P-M-G-L-5′. The genes are separated by conserved gene junctions, and phylogenetic analysis of the L sequence revealed that CrERV forms a separate branch with Siniperca chuatsi rhabdovirus (SCRV) and hybrid snakehead rhabdovirus C1207 (HSHRV-C1207). This is the frst report of the complete sequence of CrERV from the Chinese rice-feld eel in China. Introduction The Chinese rice-feld eel, Monopterus albus (family, Syn- branchidae; order, Synbranchiformes), is a major economic freshwater species in China and other Asian countries [1]. It can breathe air and crawl over land [2]. The Chinese rice- feld eel has recently become a target species for aquaculture in China due to its rapid growth and adaptability to cage- culture conditions [3]. Previous studies on Chinese rice-feld eels have focused on sex reversal characteristics [4], artifcial rearing tech- niques for larvae [5], and dietary nutritional requirements [6]. However, production of larvae and adults remains un- industrialized, and artifcial rearing of Chinese rice-feld eels has been impacted by mortality events due to unknown causes [7]. Nutrition, breeding density, and water quality contribute to the low survival rates of the Chinese rice-feld eel larvae [7, 8]. Moreover, previous studies have shown that parasitic, bacterial, and viral infections can cause seri- ous losses in adult eels under intensive culture conditions [9–11]. In China, specifc diseases that afect both Chinese rice-feld eel larvae and adults are yet to be reported. In the summer of 2017, a farm that produces Chinese rice-feld eels in Hubei, Central China, reported a massive mortality (90–100%) event that resulted in signifcant eco- nomic losses. Despite dietary changes and administration of various treatments, the mortality rate remained high. Examination of Chinese rice-feld eels showed limited evi- dence of parasitic or bacterial disease, and therefore samples of moribund eels were screened for viral isolation. It was determined that a rhabdovirus was the causative agent of the Handling Editor: William G Dundon. Wenzhi Liu and Yuding Fan and contributed equally to this paper. * Lingbing Zeng zlb@yf.ac.cn 1 Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China 2 College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China 3 Department of Fish and Wildlife Sciences and the Aquaculture Research Institute, University of Idaho, Moscow, ID 83843-1136, USA