Fu Yuting, Mao Can, Wan Jianfei, Sun Qianqian, Yu Fangzhao, Sun Jie, Wu Jiang, Li Yong, Dong Chuanfu
State Key Laboratory of Biocontrol (SKLBC, Guangzhou)/Southern Marine Science and Engineering Guangdong Laboratory (SML, Zhuhai), School of Life Sciences of Sun Yat-Sen University, Guangzhou, China.
Institute of Aquatic Economic Animals and Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou, China.
J Fish Dis. 2025 Jun 20:e14161. doi: 10.1111/jfd.14161.
Scale drop disease virus (SDDV) is a distinct member of the genus Megalocytivirus within the family Iridoviridae, which was recently identified as a causative agent of yellowfin seabream Acanthopagrus latus ascitic diseases (YFSBAD). Here, a molecular surveillance of SDDV in pond-cultured yellowfin seabream was conducted during 2021 to 2023 in Zhuhai, the most significant breeding region for this fish species in China. A total of 73 batches of naturally diseased yellowfin seabream samples were collected for SDDV detection. As a result, 31 samples were confirmed SDDV positive by conventional PCR detection, among which 9 additional SDDVs were isolated by using MFF-1 cell line, and 4 isolates were further validated by monoclonal antibody-based immunofluorescence assays. Multiple alignment and phylogenetic analysis revealed that these isolates shared the identical mcp sequences and were clustered within the same clade. Additionally, the complete genome sequence of a new SDDV isolate (SDDV-ZH918/23) was determined and annotated. The result shows that SDDV-ZH918/23 consists of 131,741 bp and encodes 143 putative open reading frames. The genome collinearity analysis demonstrated very high nucleotide similarity among all SDDV isolates distributed in China and other Asian countries. Unexpectedly, a 152 bp deletion mutant was also found in two SDDV isolates. Collectively, our study once again demonstrates that SDDV acts as an emerging etiological agent in farmed yellowfin seabream, and a partial deletion mutant of the SDDV genome was first recorded.
鳞片脱落病病毒（SDDV）是虹彩病毒科中巨细胞病毒属的一个独特成员，最近被确定为黄鳍鲷腹水病（YFSBAD）的病原体。在此，于2021年至2023年期间在中国黄鳍鲷最重要的养殖区域珠海，对池塘养殖的黄鳍鲷进行了SDDV的分子监测。总共收集了73批自然发病的黄鳍鲷样本用于SDDV检测。结果，通过常规PCR检测确认31个样本SDDV呈阳性，其中利用MFF - 1细胞系又分离出9株SDDV，并且通过基于单克隆抗体的免疫荧光试验进一步验证了4株分离株。多重比对和系统发育分析表明，这些分离株具有相同的主要衣壳蛋白（mcp）序列，并聚集在同一进化枝内。此外，还测定并注释了一株新的SDDV分离株（SDDV - ZH918/23）的完整基因组序列。结果显示，SDDV - ZH918/23由131,741 bp组成，编码143个推定的开放阅读框。基因组共线性分析表明，分布在中国和其他亚洲国家的所有SDDV分离株之间具有非常高的核苷酸相似性。出乎意料的是，在两株SDDV分离株中还发现了一个152 bp的缺失突变体。总体而言，我们的研究再次证明SDDV是养殖黄鳍鲷中一种新出现的病原体，并且首次记录了SDDV基因组的部分缺失突变体。
