Hoai Truong Dinh, Nishiki Issei, Yoshida Terutoyo, Nakai Toshihiro
Faculty of Agriculture, University of Miyazaki, Gakuen kibanadai nishi 1-1, Miyazaki 889-2192, Japan.
Dis Aquat Organ. 2018 Mar 22;128(1):81-86. doi: 10.3354/dao03212.
Three lytic phages (PLgW-1, PLgY-16, and PLgY-30) were previously used for phage-typing Lactococcus garvieae, a bacterial pathogen of various marine fish species, and were demonstrated to be potential therapeutants for infections caused by L. garvieae. The morphology, host range, and efficacy of these phages have not been investigated in detail, however. The current study examined the lysis spectrum of these 3 phages against 16 different genotypes of L. garvieae and the influence of a bacterial capsule on phage efficacy, to aid in developing an effective treatment for lactococcosis in fish. Morphological analysis by transmission electron microscopy revealed that all 3 phages belonged to the family Siphoviridae and had a minor difference in morphology. These phages lysed a high proportion of their bacterial host (93.7% of the different L. garvieae genotypes). In addition, the efficacy of the plating assays was affected by both the phages and their bacterial host, in which phage efficacy was clearly affected by a bacterial capsule. The results of this study may be useful for developing appropriate strategies to use these phages to control various genotypes of L. garvieae causing disease in marine fish.
此前，三种裂解性噬菌体（PLgW - 1、PLgY - 16和PLgY - 30）被用于对加氏乳球菌进行噬菌体分型，加氏乳球菌是多种海洋鱼类的细菌病原体，并且已证明这些噬菌体是治疗由加氏乳球菌引起的感染的潜在治疗剂。然而，尚未对这些噬菌体的形态、宿主范围和效力进行详细研究。本研究检测了这三种噬菌体对16种不同基因型加氏乳球菌的裂解谱以及细菌荚膜对噬菌体效力的影响，以帮助开发一种有效的鱼类乳球菌病治疗方法。通过透射电子显微镜进行的形态学分析表明，所有三种噬菌体均属于长尾噬菌体科，并且在形态上存在微小差异。这些噬菌体可裂解很大比例的细菌宿主（93.7%的不同加氏乳球菌基因型）。此外，平板试验的效力受噬菌体及其细菌宿主的影响，其中噬菌体效力明显受细菌荚膜的影响。本研究结果可能有助于制定适当的策略，利用这些噬菌体来控制在海洋鱼类中引起疾病的各种基因型加氏乳球菌。
