Nakai T, Sugimoto R, Park K H, Matsuoka S, Mori K, Nishioka T, Maruyama K
Faculty of Applied Biological Science, Hiroshima University, Higashihiroshima, Japan.
Dis Aquat Organ. 1999 Jun 23;37(1):33-41. doi: 10.3354/dao037033.
The present study describes the in vitro and in vivo survival of Lactococcus garvieae bacteriophages and the potential of the phage for controlling experimental L. garvieae infection in yellowtail. Anti-L. garvieae phages persisted well in various physicochemical (water temperature, salinity, pH) and biological (feed, serum and alimentary tract extracts of yellowtail) conditions, except for low acidity. In the in vivo, the phage PLgY-16 was detected in the spleens of yellowtail until 24 h after intraperitoneal (i.p.) injection, or the phage was recovered from the intestine of yellowtail 3 h after the oral administration of phage-impregnated feed but undetectable 10 h later. Simultaneous administration of live L. garvieae and phage enhanced recovery of the phage from the spleen or intestine. The survival rate was much higher in yellowtail that received i.p. injection of the phage after i.p. challenge with L. garvieae, compared with that of control fish without phage injection. When fish were i.p. injected with phage at different hours after L. garvieae challenge, higher protective effects were demonstrated in fish that received phage treatment at the earlier time. Protection was also obtained in yellowtail receiving phage-impregnated feed, in which fish were challenged by an anal intubation with L. garvieae. Anal-intubated L. garvieae were detected constantly in the spleens of the control fish, while they were detected sporadically and disappeared from the phage-treated fish 48 h later. On the other hand, orally administered phage was detected at high plaque-forming units from the intestines and spleens of the phage-treated fish until 48 h later. These results indicate that intraperitoneally or orally administered anti-L. garvieae phage prevented fish from experimental L. garvieae infection, suggesting potential use of the phage for controlling the disease.
本研究描述了加氏乳球菌噬菌体在体外和体内的存活情况，以及该噬菌体控制黄尾鱼实验性加氏乳球菌感染的潜力。除低酸度环境外，抗加氏乳球菌噬菌体在各种物理化学条件（水温、盐度、pH值）和生物条件（黄尾鱼的饲料、血清和消化道提取物）下均能良好存活。在体内实验中，腹腔注射后，噬菌体PLgY - 16在黄尾鱼脾脏中可检测到24小时，或在口服含噬菌体饲料3小时后从黄尾鱼肠道中回收，但10小时后无法检测到。同时给予活的加氏乳球菌和噬菌体可提高噬菌体从脾脏或肠道中的回收率。与未注射噬菌体的对照鱼相比，在用加氏乳球菌进行腹腔攻击后再腹腔注射噬菌体的黄尾鱼存活率要高得多。当在加氏乳球菌攻击后的不同时间给鱼腹腔注射噬菌体时，早期接受噬菌体治疗的鱼表现出更高的保护效果。给黄尾鱼投喂含噬菌体饲料也能获得保护，这些鱼通过肛门插管接受加氏乳球菌攻击。在对照鱼的脾脏中持续检测到经肛门插管的加氏乳球菌，而在接受噬菌体治疗的鱼中，48小时后偶尔检测到并消失。另一方面，在噬菌体治疗的鱼的肠道和脾脏中，直到48小时后仍能检测到高噬菌斑形成单位的口服噬菌体。这些结果表明，腹腔或口服给予抗加氏乳球菌噬菌体可预防黄尾鱼的实验性加氏乳球菌感染，提示该噬菌体在控制该病方面具有潜在用途。
