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Studies on host-parasite relationship and control of Cryptocaryon irritans using artificial culture technique

人工培养技术研究刺激白点虫的宿主-寄生虫关系及防治

基本信息

批准号：
18380112
负责人：
YOSHINAGA Tomoyoshi
金额：
$ 10.73万
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 (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2009
项目状态：
已结题

项目摘要

We conducted a series of studies on Cryptocaryon irritans, the parasitic ciliate causing white spot disease of marine fish, using an in vitro culture technique for the ciliate, which we had developed. For analyses of host-parasite relationship between the parasite and fish, we examined the cultured fish cells that were used as feed of the parasite and transformed by the parasite in the medium used for in vitro culture, with morphology, DNA electrophoresis of genemic DNA and a detection method of apoptosis (TUNNEL method). Results obtained by the examination strongly indicated that the parasite cause apoptosis in fish cells and utilizing apoptotic cells as food. We developed an in vitro screening method of drug candidates for the disease utilizing the culture method. Using the method, we assayed in vitro efficacies of anti-protozoal drugs used for human and domestic animals and found that ionophoric antibiotics had killing effect on the parasite. After determining the safe concentration of oral administration of two ionphoric antibiotics, or sodium salinomycin and sodium semduramicin, in Japanese flounder, Paralichthys olivaceus, we examined the effects of oral administration of the two antibiotics on the parasitic stage of C. irritans in Japanese flounder and found killing effect and growth-inhibiting effect in the former antibiotic. Based on the these findings, we examined the efficacy of salinomycin for prevention and treatment of white spot disease of marine fish, in which we fed flounders artificial food pellets supplemented with salynomycin at 200ppm. In the experiment, salynomycin significantly retarded death of flounder, indicating the drug can be a very good candidate drug for future medication of the disease.

我们利用我们开发的纤毛虫体外培养技术，对引起海水鱼类白斑病的寄生纤毛虫——刺激白点虫进行了一系列研究。为了分析寄生虫与鱼类之间的宿主-寄生虫关系，我们对作为寄生虫饲料并在体外培养的培养基中经寄生虫转化的培养鱼细胞进行形态学、基因DNA电泳和细胞凋亡检测方法（TUNNEL法）进行检查。检查结果强烈表明该寄生虫引起鱼细胞凋亡并利用凋亡细胞作为食物。我们开发了一种利用培养方法对该疾病候选药物进行体外筛选的方法。利用该方法，我们测定了用于人和家畜的抗原虫药物的体外疗效，发现离子载体抗生素对寄生虫具有杀灭作用。在确定了牙鲆(Paralichthys olivaceus)口服两种离子型抗生素盐霉素钠和赛杜霉素钠的安全浓度后，我们研究了两种抗生素口服给药对牙鲆C. irritans寄生阶段的影响，发现前者具有杀灭作用和生长抑制作用。基于这些发现，我们检查了盐霉素对预防和治疗海水鱼类白斑病的功效，其中我们向比目鱼喂食添加了200ppm盐霉素的人工颗粒饲料。在实验中，沙利霉素显着延缓了牙鲆的死亡，表明该药物可以成为未来治疗该疾病的非常好的候选药物。