Zhang Jingdan, Xu Huizhong, Yang Hu, Li Jia, Xiao Shuai, Hu Shengbiao, Yan Fu, Xia Liqiu, Zhang Youming
State Key Laboratory of Developmental Biology of Freshwater Fishes, Hunan Provincial Key Laboratory of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha, China.
Helmholtz International Lab for Anti-Infectives, Shandong University-Helmholtz Institute of Biotechnology, State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
Virus Res. 2021 Dec;306:198581. doi: 10.1016/j.virusres.2021.198581. Epub 2021 Sep 21.
Plesiomonas shigelloides is an important fish pathogen that causes significant losses in aquaculture. Phage therapy is a new approach to overcome the problem of multidrug-resistant bacteria. Herein, a virulent phage of P. shigelloides was isolated from the intestines of grass carp. This phage belongs to the Siphoviridae family and was designated PSP01. The optimal multiplicity of infection of PSP01 was 1 with a latent period of 30 min and a lytic period of 140 min. Good activity was observed over a wide range of temperatures (-20 °C-50 °C), pH values (3-12), and NaCl concentrations (0.1-3.5%). The phage PSP01 lysis cassette is composed of 3 genes, HolPSP, LysPSP-1 and LysPSP-2. Expression of HolPSP or LysPSP-2 in Escherichia coli resulted in bacterial lysis, and a synergistic effect was observed when the HolPSP and LysPSP-1 proteins were co-expressed. In-frame deletion uncovered an important role of the transmembrane domain (TMD) in HolPSP and the signal peptide (SP) in LysPSP-2 for bacterial lysis function. The protective effects of phage PSP01 were investigated by intraperitoneal injection into grass carp infected with P. shigelloides, showing a 33.3% increase in the survival rate of the infected grass carp. Pathological analysis of the spleens from the infected grass carp revealed alleviation of the pathological symptoms. In conclusion, isolation and bacterial lysis investigations of phage PSP01 provide a new tool for the control of fish pathogens and possesses potential for aquaculture applications.
类志贺邻单胞菌是一种重要的鱼类病原体，会给水产养殖造成重大损失。噬菌体疗法是一种克服多重耐药细菌问题的新方法。在此，从草鱼肠道中分离出一种类志贺邻单胞菌的烈性噬菌体。该噬菌体属于长尾噬菌体科，被命名为PSP01。PSP01的最佳感染复数为1，潜伏期为30分钟，裂解期为140分钟。在广泛的温度（-20℃至50℃）、pH值（3至12）和NaCl浓度（0.1%至3.5%）范围内均观察到良好的活性。噬菌体PSP01裂解盒由3个基因组成，即HolPSP、LysPSP-1和LysPSP-2。HolPSP或LysPSP-2在大肠杆菌中的表达导致细菌裂解，当HolPSP和LysPSP-1蛋白共表达时观察到协同效应。框内缺失揭示了跨膜结构域（TMD）在HolPSP中的重要作用以及信号肽（SP）在LysPSP-2中的细菌裂解功能。通过腹腔注射到感染类志贺邻单胞菌的草鱼体内来研究噬菌体PSP01的保护作用，结果显示感染草鱼的存活率提高了33.3%。对感染草鱼脾脏的病理分析表明病理症状有所减轻。总之，噬菌体PSP01的分离和细菌裂解研究为控制鱼类病原体提供了一种新工具，并具有水产养殖应用潜力。
