Jintasakul Valalak, Pattano Jiranan, Preeprem Sutima, Mittraparp-Arthorn Pimonsri
Division of Biological Science, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90110, Thailand.
Center of Research and Innovation Development of Microbiology for Sustainability (RIMS), Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla, 90110, Thailand.
Virol J. 2025 Jan 30;22(1):21. doi: 10.1186/s12985-025-02637-6.
Vibrio parahaemolyticus is a marine bacterium causing seafood-associated gastrointestinal illness in humans and acute hepatopancreatic necrosis disease (AHPND) in shrimp. Bacteriophages have emerged as promising biocontrol agents against V. parahaemolyticus. This study characterizes Vibrio phage VPK8, focusing on host specificity, efficiency of plating (EOP) variability across V. parahaemolyticus isolates from diverse sources and other Vibrio species, morphology, genomic features, and bacteriolytic potential.
Vibrio phage VPK8 was isolated from blood cockles in Thailand using a mixed-host approach and purified via the double-layer agar method. Host specificity was evaluated using spot assays and EOP measurements against 120 Vibrio strains, including AHPND-associated, clinical, and seafood isolates. Phage morphology was characterized by transmission electron microscopy (TEM), while genomic features were analyzed using next-generation sequencing. Lytic characteristics, including latent period and burst size, were determined through one-step growth curves, and bacterial growth reduction was evaluated over a 24-h.
Vibrio phage VPK8 is a lytic phage with a 42,866 bp linear double-stranded genome, G + C content of 49.4%, and 48 coding sequences. Phylogenetic analysis grouped it within the Autographiviridae family, showing 95.96% similarity to Vibrio phage vB_VpaP_MGD1. Viral proteomic analysis placed VPK8 within the Pseudomonadota host group. Spot assays indicated broad lytic activity, but EOP analysis revealed high infectivity in clinical and seafood V. parahaemolyticus isolates, as well as some V. cholerae and V. mimicus strains. TEM revealed an icosahedral head (~ 60 nm) and a short tail. At a multiplicity of infection of 0.01, VPK8 exhibited a latent period of 25 min, a burst size of 115, and effectively inhibited the reference host V. parahaemolyticus PSU5124 within 6 h, maintaining its lytic activity and stability for over 24 h.
This study provides a detailed characterization of Vibrio phage VPK8 which exhibits targeted infectivity with high EOP in clinical and seafood V. parahaemolyticus isolates, as well as selected Vibrio species. Its stable lytic performance, rapid replication, and genomic safety suggest its potential for phage-based applications. Further studies should explore its in vivo efficacy and the genetic features contributing to phage resistance mechanisms, enhancing its potential applicability in managing Vibrio-related diseases.
副溶血性弧菌是一种海洋细菌，可导致人类食用海鲜后出现胃肠道疾病，并引发虾类的急性肝胰腺坏死病（AHPND）。噬菌体已成为对抗副溶血性弧菌的有前景的生物防治剂。本研究对副溶血性弧菌噬菌体VPK8进行了表征，重点关注宿主特异性、来自不同来源的副溶血性弧菌分离株及其他弧菌属物种的平板效率（EOP）变异性、形态、基因组特征和溶菌潜力。
采用混合宿主法从泰国的血蚶中分离出副溶血性弧菌噬菌体VPK8，并通过双层琼脂法进行纯化。使用点滴试验和EOP测量法对120株弧菌菌株进行宿主特异性评估，这些菌株包括与AHPND相关的、临床的和海鲜分离株。通过透射电子显微镜（TEM）对噬菌体形态进行表征，同时使用下一代测序技术分析基因组特征。通过一步生长曲线确定包括潜伏期和裂解量在内的裂解特性，并在24小时内评估细菌生长的减少情况。
副溶血性弧菌噬菌体VPK8是一种裂解性噬菌体，其线性双链基因组大小为42,866 bp，G+C含量为49.4%，有48个编码序列。系统发育分析将其归入自配病毒科，与副溶血性弧菌噬菌体vB_VpaP_MGD1的相似性为95.96%。病毒蛋白质组分析将VPK8归入假单胞菌宿主组。点滴试验表明其具有广泛的裂解活性，但EOP分析显示，它对临床和海鲜来源的副溶血性弧菌分离株以及一些霍乱弧菌和拟态弧菌菌株具有高感染性。TEM显示其头部为二十面体（约60 nm），尾部较短。在感染复数为0.01时，VPK8的潜伏期为25分钟，裂解量为115，并在6小时内有效抑制了参考宿主副溶血性弧菌PSU5124，其裂解活性和稳定性可维持超过24小时。
本研究对副溶血性弧菌噬菌体VPK8进行了详细表征，该噬菌体对临床和海鲜来源的副溶血性弧菌分离株以及选定的弧菌属物种表现出具有高EOP的靶向感染性。其稳定的裂解性能、快速复制和基因组安全性表明其在基于噬菌体的应用中的潜力。进一步的研究应探索其体内疗效以及导致噬菌体抗性机制的遗传特征，以增强其在管理弧菌相关疾病中的潜在适用性。
