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Studies on infection cycles of newly emerging and re-emerging diseases of fishes

鱼类新发和再发疾病感染周期的研究

基本信息

批准号：
14206024
负责人：
OGAWA Kazuo
金额：
$ 28.2万
依托单位：
THE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14206024/
关键词：
emerging disease Neoheterobothrium birnavirus cold water disease white spot disease microsporidium wild fish cultured fish

项目摘要

1.Field investigation of the flounder birnavirus and VHSV among wild marine fishes showed that aquabirnavirus was isolated from horse mackerel, Japanese flounder and dark banded rockfish, and that VHSV was detected from Japanese flounder and sand lance. All isolates of VHSV except one belonged to Genogroup 3 (American genogroup). VHSV was easily transmitted by water-borne route from infected to uninfected fish, suggesting that the infection cycle completed between wild and cultured flounder.2.Occurrences of Neoheterobothrium hirame in 0-and 1-year-old Japanese flounder in Miyako Bay, Iwate Prefecture and Obama Bay, Fukui Prefecture were surveyed. In both areas, infection levels in both wild and released flounders were high in winter and low in summer and were several fold higher in Obama than in Miyako.3.Twenty three isolates of Flavobacterium psychrophilum, the causative bacterium of cold-water disease, were found in wild freshwater fishes (crucian carp, dace and ayu). We tried to apply the 5 isolates of bacteriolytic phages from ayu farms as biological control of cold-water disease.4.Sedimentation velocity and time required for the cyst formation of the protomont of Cryptocaryon irritans was determined. The determined values indicate that the parasite cyst is formed on the sea bed and the infection cycle of the parasite occurs between the sea bottom and the net-cage. Furthermore, it is suggested that the outbreak of the parasite is related to tide.5.Development of Kabatana takedai was suppressed by low temperature, but recurred by increase of temperature, suggesting that a release of latently infected fish results in spread of the disease. The unknown infective stage, ca. 40μm in size, was shown to originate in the dam located in an upper stream of the Chitose hatchery and invade fish perorally.

1.野外海鱼比目鱼病毒和VHSV调查结果显示，从马鲛鱼、比目鱼和黑带岩鱼中分离到比目鱼病毒，从比目鱼和沙枪鱼中检测到VHSV。除1株VHSV分离株属于基因3（美洲基因组）外，其余均为VHSV分离株。VHSV很容易通过水媒途径从感染的鱼传播到未感染的鱼，表明感染周期在野生和养殖比目鱼之间完成。调查了岩手县宫古湾和福井县奥巴马湾0 ~ 1岁日本比目鱼中平名新异硼酸菌的发生情况。在这两个地区，野生比目鱼和放生比目鱼的感染水平在冬季高，在夏季低，奥巴马比宫古高出几倍。从野生淡水鱼（鲫鱼、鲮鱼和阿鱼）中分离出23株致病菌嗜冷黄杆菌。我们尝试将5株产自阿玉养殖场的溶菌噬菌体作为冷水病的生物防治。测定隐核虫刺激囊前囊形成所需的沉降速度和时间。测定值表明，寄生虫囊形成于海底，寄生虫的感染周期发生在海底与网箱之间。此外，认为寄生虫的爆发与潮汐有关。低温抑制了竹台鱼的发展，但温度升高会使其复发，这表明释放潜伏感染的鱼会导致疾病的传播。未知感染期大小约为40μm，起源于位于Chitose孵化场上游的大坝，并经口侵入鱼类。