Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China.
Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, PR China.
Virus Res. 2015 Jul 2;205:45-53. doi: 10.1016/j.virusres.2015.05.010. Epub 2015 May 19.
Singapore grouper iridovirus (SGIV) encodes a number of microRNAs (miRNAs) during infection. Among these, SGIV-miR-13 has robust expression at early stage after SGIV inoculation, raising a huge possibility that it participates in the viral infection. In the present study, we found that SGIV-miR-13 overexpression led to a significant reduction in viral load in cultured fish cells with SGIV infection, as demonstrated by less level of viral transcripts, viral-induced cytopathic effect (CPE) and assembled viral particles. In silico analysis showed that SGIV-miR-13 maps antisense to the coding region of SGIV major capsid protein (SGIV-MCP), suggesting it to be a potential target of SGIV-miR-13. Coincidently, SGIV-miR-13 showed an inverted expression profile with SGIV-MCP during SGIV infection, and luciferase reporter assay further demonstrated SGIV-MCP as the direct target of SGIV-miR-13. Functionally, overexpression of SGIV-miR-13 inhibited, whereas knockdown of SGIV-miR-13 restored the expression of SGIV-MCP during viral infection, resulting in altered viral progeny emergences. In conclusion, our data suggest that SGIV-miR-13 functions in a negative regulatory mechanism to restrict early viral replication, and thus prevents excessive cellular antiviral responses during SGIV infection. The detailed investigation of SGIV encoded miRNAs may provide new insights into the mechanism of iridovirus pathogenesis.
新加坡石斑鱼虹彩病毒（SGIV）在感染过程中编码许多 microRNAs（miRNAs）。其中，SGIV-miR-13 在 SGIV 接种后早期具有强大的表达，这极大地表明它参与了病毒感染。在本研究中，我们发现 SGIV-miR-13 的过表达导致感染 SGIV 的培养鱼类细胞中的病毒载量显著降低，这表现为病毒转录物、病毒诱导的细胞病变效应（CPE）和组装的病毒颗粒水平降低。计算机分析表明，SGIV-miR-13 与 SGIV 主要衣壳蛋白（SGIV-MCP）的编码区反义，表明它可能是 SGIV-miR-13 的潜在靶标。巧合的是，SGIV-miR-13 在 SGIV 感染过程中与 SGIV-MCP 表现出相反的表达模式，荧光素酶报告基因检测进一步证明 SGIV-MCP 是 SGIV-miR-13 的直接靶标。功能上，SGIV-miR-13 的过表达抑制了，而 SGIV-miR-13 的敲低则恢复了病毒感染过程中 SGIV-MCP 的表达，导致病毒后代的出现发生改变。总之，我们的数据表明，SGIV-miR-13 作为一种负调控机制，在限制早期病毒复制方面发挥作用，从而防止在 SGIV 感染期间过度的细胞抗病毒反应。对 SGIV 编码的 miRNAs 的详细研究可能为虹彩病毒发病机制提供新的见解。
