Fu Jingyun, Li Ying, Zhao Lihong, Wu Chunguang, He Zengguo
College of Medicine and Pharmacy, Ocean University of China, Qingdao, China.
Marine Biomedical Research Institute of Qingdao Co., Ltd., Qingdao, China.
Front Microbiol. 2023 May 12;14:1105924. doi: 10.3389/fmicb.2023.1105924. eCollection 2023.
Phage therapy was taken as an alternative strategy to antibiotics in shrimp farming for the control of species of and which cause substantial mortality and significant economic losses. In this study, a new phage vB_ValM_PVA8 (PVA8), which could efficiently infect pathogenic isolates of and , was isolated from sewage water and characterized by microbiological and genomic analyses. The phage was characterized to be a member of the family with elongated head and contractile tail by transmission electron microscopy. Genome sequencing showed that PVA8 had a 246,348-bp double-stranded DNA genome with a G + C content of 42.6%. It harbored totally 388 putative open reading frames (ORFs), among them 92 (23.71%) assigned to functional genes. Up to 27 transfer RNA (tRNA) genes were found in the genome, and the genes for virulence, antibiotic resistance, and lysogeny were not detected. NCBI genomic blasting results and the phylogenetic analysis based on the sequences of the large terminase subunits and the DNA polymerase indicated that PVA8 shared considerable similarity with phage V09 and bacteriophage KVP40. The phage had a latent period of 20 min and a burst size of 309 PFUs/infected cell with the host , and it was stable over a broad pH range (4.0-11.0) and a wide temperature span (-80°C to 60°C), respectively, which may benefit its feasibility for phage therapy. In addition, it had the minimum multiplicity of infection (MOI) of 0.0000001, which revealed its strong multiplication capacity. The shrimp cultivation lab trials demonstrated that PVA8 could be applied in treating pathogenic infection disease of shrimp with a survival rate of 88.89% comparing to that of 34.43% in the infected group, and the pond application trails confirmed that the implementation of PVA8 could rapidly yet effectively reduce the level of the . Taken together, PVA8 may be potential to be explored as a promising biological agent for control in aquaculture farming industry.
噬菌体疗法被视为虾类养殖中抗生素的替代策略，用于控制引起大量死亡和重大经济损失的弧菌属和发光杆菌属物种。在本研究中，从污水中分离出一种新的噬菌体vB_ValM_PVA8（PVA8），它可以有效感染弧菌属和发光杆菌属的致病分离株，并通过微生物学和基因组分析对其进行了表征。通过透射电子显微镜观察，该噬菌体被鉴定为长尾噬菌体科的成员，具有细长的头部和可收缩的尾部。基因组测序表明，PVA8有一个246,348 bp的双链DNA基因组，G + C含量为42.6%。它总共含有388个推定的开放阅读框（ORF），其中92个（23.71%）被分配到功能基因。在基因组中发现了多达27个转运RNA（tRNA）基因，未检测到毒力、抗生素抗性和溶原性相关基因。NCBI基因组比对结果以及基于大末端酶亚基和DNA聚合酶序列的系统发育分析表明，PVA8与弧菌噬菌体V09和噬菌体KVP40有相当大的相似性。该噬菌体对宿主弧菌的潜伏期为20分钟，裂解量为309个噬菌斑形成单位/感染细胞，并且分别在较宽的pH范围（4.0 - 11.0）和较宽的温度跨度（-80°C至60°C）内稳定，这可能有利于其用于噬菌体疗法的可行性。此外，它的最小感染复数（MOI）为0.0000001，这表明其强大的增殖能力。对虾养殖的实验室试验表明，PVA8可用于治疗虾的致病性弧菌感染疾病，与感染组34.43%的存活率相比，其存活率为88.89%，池塘应用试验证实，施用PVA8可以迅速而有效地降低弧菌水平。综上所述，PVA8有可能被开发为水产养殖业中控制弧菌的一种有前景的生物制剂。
