养殖大菱鲆蟹栖异阿脑虫感染及其危害

从养殖大菱鲆（Scophthalmus maximus）患病鱼体中分离出一种寄生性纤毛虫，通过活体观察、碳酸银法染色和扫描电镜对其形态学进行特征分析。经鉴定，该纤毛虫为蟹栖异阿脑虫（Mesanophrys carcini Groliere ＆ Leglise，1977），隶属于寡膜纲、盾纤目、嗜污科、异阿脑虫属。患病鱼常表现为静伏池底，体色变暗，活力弱，摄食差，生长减慢，并发生急、慢性死亡。最明显的特征是病灶部位变白，略有浮肿，触摸柔软。流行病学特征显示，在大菱鲆的苗期、养成期、亲鱼培育期均可发生纤毛虫感染，幼鱼期发生率较高，发病水温14-20℃，盐度12～40。组织病理学观察分析表明，病灶组织处以盾纤虫为主要入侵微生物，常伴有细菌存在，但没有发现病毒性细胞病变和霉菌等其他寄生生物。     

Effects of clioquinol on the scuticociliatosis‐causing protozoan Miamiensis avidus in olive flounder Paralichthys olivaceus

Scuticociliatosis is a devastating and intractable protozoal disease in olive flounder, leading to a significant loss throughout the year. This study aimed to investigate a systemically effective antiscuticociliatosis agent for olive flounder for better absorption into the infected internal organs. The in vitro and in vivo antiscuticociliatosis effects of clioquinol (CQ) were examined after screening 30 biocidal agents against the highly pathogenic scuticociliate Miamiensis avidus. CQ was the most potent in vitro drug of those tested against cultured M. avidus. CQ was the least toxic in healthy olive flounder among the drugs that exhibit high potencies. In olive flounder, a single intramuscular injection of 40 mg/kg CQ significantly reduced mortality caused by artificial infection with M. avidus, and 10–20 mg/kg CQ increased fish survival times. CQ was also effective in naturally infected scuticociliatosis. Ciliate cell numbers were lower when CQ was injected in most organs, including the brain. CQ was well absorbed by the internal organs after intramuscular injection. This study suggests that CQ can be considered as a potential antiscuticociliatosis agent for systemic administration in olive flounder.     

Antigenic differences of the scuticociliate Miamiensis avidus from Japan

In Japan and Korea, outbreaks of scuticociliatosis have frequently occurred in Japanese flounder, Paralichthys olivaceus . Morphological observations and small subunit rRNA gene sequences have shown that the causative agent of scuticociliatosis in the flounder is Miamiensis avidus (syn. Philasterides dicentrarchi ). In this study, we elucidated the antigenic differences between six Japanese M. avidus isolates as an initial step toward developing an effective vaccine against the disease. Four Japanese flounder isolates (IyoI, Nakajima, JF05To and Mie0301 isolates), one spotted knifejaw, Oplegnathus punctatus, isolate (SK05Kyo), and one ridged-eye flounder, Pleuronichthys cornutus , isolate (RF05To) were subjected to serological analysis. Antisera against IyoI, SK05Kyo, Nakajima and Mie0301 isolates were raised in rabbits and used for immobilization assays and Western blotting. Immobilization assays showed that the six isolates could be divided into three groups, tentatively designated serotype I for IyoI, JF05To, RF05To, SK05Kyo, serotype II for Nakajima and serotype III for Mie0301. Western blotting results supported these three serotypes, with marked similarities in the banding profiles of IyoI, JF05To, RF05To and SK05Kyo isolates, which were distinct from the Nakajima and Mie0301 isolates. Three isolates, IyoI, Nakajima and Mie0301 that were selected as representatives of each serotype, were highly pathogenic to Japanese flounder by experimental infection. Based on these findings, we propose that there are at least three M. avidus serotypes in Japan.