Review of the sequential development of Loma salmonae (Microsporidia) based on experimental infections of rainbow trout (Oncorhynchus mykiss) and Chinook salmon (O tshawytscha)
Review of the sequential development of Loma salmonae (Microsporidia) based on experimental infections of rainbow trout (Oncorhynchus mykiss) and Chinook salmon (O tshawytscha)
复制标题
DOI：
10.14411/fp.2005.009
复制
发表时间：
2005-05-01
影响因子：
1.6
通讯作者：
Speare, DJ
中科院分区：
文献类型：
--
作者：
Kent, ML;Speare, DJ
沙门氏菌(Loma salmonae，Putz，Hoffman et Dunbar，1965)是一种常见的鲑科鱼类的鳃寄生虫，几乎所有属的物种都对其敏感。感染在淡水和咸水中都会发生。沙门氏菌可通过摄入孢子或受感染的组织直接传播。寄生虫感染各种器官的血管壁，但鳃是感染的主要部位。最初的感染发生在肠道，暴露后4-6周，通过标准组织学很容易在鳃中检测到异种瘤。在鳃内异种瘤形成之前，在心脏内皮细胞中发现了几个孢子形成前阶段的寄生虫。对早期感染的超微结构研究表明，游动的血细胞将分体运输到鳃，并且分生细胞发生在支柱细胞和鳃内皮下的其他细胞中。异种瘤在这些细胞中发展，导致肥大的宿主细胞充满孢子。Xenoma最终破裂，并与严重的炎症有关，在巨噬细胞中发现游离孢子。在感染的这一阶段，寄生虫的致病性最强，导致严重的脉管炎和临床疾病。虹鲑鱼(Oncorhynchus Mykis)和奇努克鲑鱼(Oncorhynchus Tshawytscha)都能从感染中恢复，但在奇努克鲑鱼没有异种瘤后，游离孢子会在肾和脾的吞噬细胞中存活数月。从感染中恢复的鱼对寄生虫表现出很强的免疫力，可持续到一岁。鱼容易通过其他途径感染孢子；同居、肛门灌洗、肌肉注射、腹膜内注射和血管内注射。自体感染可能发生在异种瘤破裂后血管内的孢子释放。沙门氏菌感染的最适温度为15-17摄氏度，允许范围为11-20摄氏度。
Loma salmonae (Putz, Hoffman et Dunbar, 1965) is a common gill parasite of salmonids, and essentially all species in the genus Oncorhynchus are susceptible. Infections occur in both fresh and salt water. Loma salmonae is directly transmissible by ingestion of spores or infected tissue. The parasite infects the wall of blood vessels of various organs, but the gill is the primary site of infection. Initial infection occurs in the intestine, and xenomas are easily detected in the gills by standard histology at 4-6 wk post-exposure. A few presporogonic stages of the parasite are found in the heart endothelium prior to xenoma formation in the gills. Ultrastructure studies of early infections demonstrated that wandering blood cells transport the meronts to the gills, and that merogony occurs in pillar cells and other cells underlying the gill endothelium. Xenomas develop in these cells, resulting in hypertrophied host cells filled with spores. Xenomas ultimately rupture, and are associated with severe inflammation in which free spores are found in macrophages. The parasites are most pathogenic during this phase of the infection, resulting in severe vasculitis and clinical disease. Both rainbow trout (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus tshawytscha) recover from infections, but free spores persist in kidney and spleen phagocytes for many months after xenomas are absent in Chinook salmon. Fish that have recovered from the infection show strong immunity against the parasite, lasting up to I year. Fish are susceptible to infection by other routes of exposure by spores; co-habitation, anal gavage, and intramuscular, intraperitoneal and intravascular injection. Autoinfection probably occurs following release of spores in blood vessels after xenomas rupture. The optimal temperature for L. salmonae infections is 15-17 degrees C, with a permissive range of 11-20 degrees C.