International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan.
Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung, Taiwan.
J Fish Dis. 2020 Jul;43(7):757-774. doi: 10.1111/jfd.13173. Epub 2020 May 17.
Photobacteriosis, caused by Photobacterium damselae subsp. piscicida (Phdp), is a serious disease in marine fish species worldwide. To date, the epidemiological characterization of this pathogen in Taiwan remains limited. In this study, we collected 39 Phdp isolates obtained from different farmed fish for phenotypic and genotypic analysis. Phenotype bioassays using API-20E and API-20NE systems showed that the Phdp is a homogeneous group. However, genotyping using the pulsed-field gel electrophoresis (PFGE) technique revealed genetic variability among Phdp isolates when 13 and 11 different PFGE band patterns were obtained with SmaI and NotI as restriction enzymes, respectively. Phylogenetic analysis using 16S rDNA and the Fur gene clustered Taiwanese isolates and other species of P. damselae in the same clade. In contrast, the ToxR phylogenetic tree, a powerful discriminatory marker, separated the two subspecies. Furthermore, the virulence-associated genes, AIP56, P55, PDP_0080, Sod and Irp1, were detected from all isolates. Virulence testing with nine representative isolates in cobia (Rachycentron canadum) and Asian sea bass (Lates calcarifer) showed that some were highly pathogenic with 80%-100% mortality rates. This study provides epidemiological data of Phdp infections in farmed fish in Taiwan, which is necessary to develop comprehensive prevention and control strategies for the disease.
发光杆菌病由发光杆菌亚种鱼致病性（Phdp）引起，是世界范围内海水养殖鱼类的一种严重疾病。迄今为止，该病原体在台湾的流行病学特征描述仍然有限。在本研究中，我们收集了来自不同养殖鱼类的 39 株 Phdp 分离株，用于表型和基因型分析。使用 API-20E 和 API-20NE 系统进行的表型生物测定表明，Phdp 是一个同质群体。然而，使用脉冲场凝胶电泳（PFGE）技术进行的基因分型显示，当分别使用 SmaI 和 NotI 作为限制酶时，Phdp 分离株之间存在遗传变异，获得了 13 和 11 种不同的 PFGE 带型。使用 16S rDNA 和 Fur 基因进行的系统发育分析将台湾分离株和其他发光杆菌亚种聚类在同一进化枝中。相比之下，ToxR 系统发育树，一种强大的鉴别标记，将两个亚种分开。此外，所有分离株均检测到与毒力相关的基因 AIP56、P55、PDP_0080、Sod 和 Irp1。在九株代表性分离株对军曹鱼（Rachycentron canadum）和亚洲鲈鱼（Lates calcarifer）的致病性试验中，一些分离株具有高致病性，死亡率为 80%-100%。本研究提供了台湾养殖鱼类中 Phdp 感染的流行病学数据，这对于制定该疾病的综合防控策略是必要的。
