Marine Biology Department, The Leon H. Charney School of Marine Sciences, University of Haifa, Mt. Carmel, 3498838 Haifa, Israel.
Department of Fisheries and Aquaculture, Central Fish Health Laboratory, Ministry of Agriculture and Rural Development, 10803 Nir David, Israel.
Parasitology. 2023 May;150(6):524-530. doi: 10.1017/S0031182023000240. Epub 2023 Mar 10.
Nile × blue tilapia hybrid ( × ) has become an important food fish in intensive freshwater aquaculture. Recently, the parasite (Cnidaria: Myxozoa) was found to infect hybrid tilapia gills at high prevalence, causing immune suppression and high mortality. Here, we explored additional characteristics of –tilapia interaction, which enable efficient proliferation of this parasite inside its specific host. Highly sensitive quantitative polymerase chain reaction (qPCR) and hybridization analyses of fry collected from fertilization ponds provided evidence to an early-life infection of fish by a myxozoan parasite, occurring less than 3 weeks post-fertilization. Because species are highly host-specific, we next compared infection rates in hybrid tilapia and in both its parental species following a 1-week exposure to infectious pond water. Analysis by qPCR and histological sections showed that while blue tilapia was as susceptible to as the hybrid, Nile tilapia appeared to be resistant. This is the first report of differential susceptibility of a hybrid fish its parental purebreds to a myxozoan parasite. These findings advance our understanding of the relationship between and tilapia fish and raise important questions regarding the mechanisms that allow the parasite to distinguish between very closely related species and to infect a specific organ at very early-life stages.
尼勒克 × 蓝罗非鱼杂交种（ × ）已成为集约化淡水水产养殖中的一种重要食用鱼。最近，发现一种寄生虫（刺胞动物门：粘孢子虫）在杂交罗非鱼的鳃中高度流行，导致免疫抑制和高死亡率。在这里，我们探讨了这种寄生虫与宿主的相互作用的其他特征，这些特征使寄生虫能够在其特定宿主内高效增殖。从受精池塘中收集的鱼苗的高灵敏度定量聚合酶链反应（qPCR）和杂交分析提供了证据，证明鱼苗在受精后不到 3 周就受到粘孢子虫寄生虫的早期感染。由于 物种具有高度的宿主特异性，我们接下来比较了在接触传染性池塘水 1 周后，杂交罗非鱼及其双亲种的感染率。qPCR 和组织学切片分析表明，虽然蓝罗非鱼和杂交罗非鱼一样容易感染 ，但尼罗罗非鱼似乎具有抗性。这是首例杂交鱼与其双亲纯种对粘孢子虫寄生虫易感性不同的报道。这些发现增进了我们对 和罗非鱼之间关系的理解，并提出了一些重要问题，即是什么机制使寄生虫能够区分非常相关的物种，并在非常早期的生命阶段感染特定器官。
