Characterization of a megalocytivirus from cultured rock bream, Oplegnathus fasciatus (Temminck & Schlege), in China

• Published in: Aquaculture Research
• Main Authors: Zhang, Min, Xiao, Zhi-zhong, Hu, Yong-hua, Sun, Li, Sun, L (reprint author), Chinese Acad Sci, Inst Oceanol, Key Lab Expt Marine Biol, 7 Nanhai Rd, Qingdao 266071, Peoples R China.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2012
• Subjects: Iridovirus; Megalocytivirus; Oplegnathus Fasciatus (Temminck & Schlege); Scophthalmus Maximus l; Fisheries; Scophthalmus maximus; Turbot
• Online Access: http://ir.qdio.ac.cn/handle/337002/12296; https://doi.org/10.1111/j.1365-2109.2011.02861.x

Megalocytivirus belongs to the Iridoviridae family and is known to affect finfish. Megalocytivirus epizootics have been reported to occur in several cultured fish species in China; however, no megalocytivirus associated with rock bream, Oplegnathus fasciatus (Temminck & Schlege), has been documented. In this study, we characterized for the first time a megalocytivirus, rock bream iridovirus (RBIV)-C1, detected in cultured rock bream in a fish farm in China that had been inflicted with a high-mortality disease outbreak. Sequence analysis of three conserved genes showed that RBIV-C1 shares over 90% overall identities with a number of known megalocytiviruses. Electron microscopic examination revealed RBIV-C1 as hexagonal particles similar to those reported for megalocytiviruses. In vivo infection study indicated that, following inoculation into rock bream, RBIV-C1 induced 100% mortality and upregulated the expression of Mx, IL-1 beta and IL-8. The infected fish exhibited pathological signs similar to those observed in naturally diseased fish. Furthermore, studies in a turbot (Scophthalmus maximus L.) model indicated that RBIV-C1 induced acute infection in turbot that led to 100% mortality. These results indicate that RBIV-C1 is highly virulent to rock bream as well as turbot and that RBIV-C1 is closely related to a number of previously reported megalocytivirus and likely a genetic variant of the latter.