Experimental infection reveals transmission of tilapia lake virus (TiLV) from tilapia broodstock to their reproductive organs and fertilized eggs
Experimental infection reveals transmission of tilapia lake virus (TiLV) from tilapia broodstock to their reproductive organs and fertilized eggs
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DOI：
10.1016/j.aquaculture.2019.734541
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发表时间：
2020-01-15
期刊：
影响因子：
4.5
通讯作者：
Mohan, Chadag Vishnumurthy
中科院分区：
文献类型：
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作者：
Ha Thanh Dong;Senapin, Saengchan;Mohan, Chadag Vishnumurthy
在我们先前的研究中，罗非鱼的早期发育阶段，包括受精卵，被测试为TiLV阳性（Dong等人，2017年a）。因此，我们假设受感染的亲鱼能够将病毒传播到它们的生殖器官，然后传播到受精卵。为了验证这一假设，采用肌肉注射法对尼罗罗非鱼（Oreochromis niloticus）亲鱼进行了实验感染，并以未感染的亲鱼作为对照组。在感染后第6天，无菌收集来自每个繁殖对的卵和精液用于体外受精。在受精后3、12和64 h，通过PCR、ISH和细胞培养对受精卵进行TiLV检测。同时，对每只亲鱼的血液、血清、肝脏和生殖器官进行TiLV分析。结果显示，通过PCR、ISH和细胞培养，从感染亲鱼中收集的所有组织（肝脏、血液、卵巢和睾丸）均检测出TiLV阳性。原位杂交显示，在肝脏血管周围的肝细胞、卵巢卵母细胞周围的结缔组织和膜以及睾丸血管附近的结缔组织中均可见强阳性信号。这些发现表明，TiLV导致罗非鱼亲鱼全身感染，病毒能够传播到生殖器官，最有可能通过血液循环系统。随后，通过PCR和ISH检测感染亲鱼产生的受精卵对TiLV呈阳性，显示受精卵内的病毒位置。本研究结果表明，TiLV可以垂直传播。因此，我们建议孵化场和增殖中心使用TiLV测试阴性亲鱼生产无TiLV罗非鱼种子。
Early developmental stages of tilapia, including fertilized eggs were tested positive for TiLV in our previous study (Dong a al., 2017a). We, therefore, hypothesized that infected broodstock is able to pass the virus to their reproductive organs and then to the fertilized eggs. In order to prove this hypothesis, Nile tilapia (Oreochromis niloticus) broodstock were experimentally infected with TiLV by intramuscular injection and non-infected broodstock were used as control group. At day 6 post infection, eggs and semen from each breeding pair were aseptically collected for in vitro fertilization. Fertilized eggs at 3, 12 and 64 h post-fertilization were subjected to detection of TiLV by PCR, ISH, and cell culture. In parallel, blood, serum, liver and reproductive organs from each broodstock were subjected to TiLV analysis. The results revealed that all collected tissues (liver, blood, ovary and testis) from infected broodstock tested positive for TiLV by PCR, ISH, and cell culture. ISH revealed strong positive signals in hepatocytes surrounding blood vessels in the liver, connective tissue and membrane surrounding the oocytes in the ovary and the connective tissue close to blood vessels in the testis. These findings suggested that TiLV causes systemic infection in tilapia broodstock with the virus being able to spread into the reproductive organs, most likely through the blood circulatory system. Subsequently, the fertilized eggs produced by infected broodstock tested positive for TiLV by PCR and ISH revealed location of the virus inside the fertilized eggs. The results of this study suggested that TiLV can be transmitted vertically. We thus recommend for hatchery and multiplication center to use TiLV-tested negative broodstock for the production of TiLV-free tilapia seeds.