Gross K A, Morrison R N, Butler R, Nowak B F
Tasmanian Aquaculture and Fisheries Institute and Aquafin CRC, School of Aquaculture, University of Tasmania, Launceston, Tasmania, Australia.
J Fish Dis. 2004 Jan;27(1):47-56. doi: 10.1046/j.1365-2761.2003.00514.x.
Previous studies have indicated that Atlantic salmon, Salmo salar L., affected by amoebic gill disease (AGD) are resistant to re-infection. These observations were based upon a comparison of gross gill lesion abundance between previously infected and naïve control fish. Anecdotal evidence from Atlantic salmon farms in southern Tasmania suggests that previous infection does not protect against AGD as indicated by a lack of temporal change in freshwater bathing intervals. Experiments were conducted to determine if previous infection of Atlantic salmon with Neoparamoeba sp. would provide protection against challenge and elucidate the immunological basis of any protection. Atlantic salmon were infected with Neoparamoeba sp. for 12 days then treated with a 4-h freshwater bath. Fish were separated into two groups and maintained in either sea water or fresh water for 6 weeks. Fish were then transferred to one tank with a naïve control group and challenged with Neoparamoeba sp. Fish kept in sea water had lower mortality rates compared with first time exposed and freshwater maintained fish, however, these data are believed to be biased by ongoing mortalities during the sea-water maintenance phase. Phagocyte function decreased over exposure time and freshwater maintained fish demonstrated an increased ability to mount a specific immune response. These results suggest that under the challenge conditions herein described, antigen exposure via infection does not induce protection to subsequent AGD.
先前的研究表明，受阿米巴鳃病（AGD）影响的大西洋鲑（Salmo salar L.）对再次感染具有抵抗力。这些观察结果是基于对先前感染的鱼和未感染的对照鱼之间鳃部病变总数的比较得出的。来自塔斯马尼亚岛南部大西洋鲑养殖场的传闻证据表明，先前的感染并不能预防AGD，这一点从淡水浸泡间隔时间没有随时间变化可以看出。进行了实验，以确定大西洋鲑先前感染新帕拉变形虫（Neoparamoeba sp.）是否能提供抵御攻击的保护作用，并阐明任何保护作用的免疫学基础。将大西洋鲑感染新帕拉变形虫12天，然后进行4小时的淡水浸泡处理。将鱼分成两组，分别在海水或淡水中饲养6周。然后将鱼转移到一个装有未感染对照组的水箱中，并用新帕拉变形虫进行攻击。与首次暴露的鱼和饲养在淡水中的鱼相比，饲养在海水中的鱼死亡率较低，然而，这些数据被认为受到海水饲养阶段持续死亡的影响而存在偏差。吞噬细胞功能随暴露时间下降，饲养在淡水中的鱼表现出更强的产生特异性免疫反应的能力。这些结果表明，在本文所述的攻击条件下，通过感染进行的抗原暴露不会诱导对后续AGD的保护作用。
