A Plant Virus Ensures Viral Stability in the Hemolymph of Vector Insects through Suppressing Prophenoloxidase Activation
A Plant Virus Ensures Viral Stability in the Hemolymph of Vector Insects through Suppressing Prophenoloxidase Activation
复制标题
植物病毒通过抑制酚氧化酶原激活来确保媒介昆虫血淋巴中的病毒稳定性
DOI：
10.1128/mbio.01453-20
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发表时间：
2020-07-01
期刊：
影响因子：
6.4
通讯作者：
Cui, Feng
中科院分区：
文献类型：
--
作者：
Chen, Xiaofang;Yu, Jinting;Cui, Feng
大比例的媒介传播的植物病毒在进入唾液腺传播到植物之前在其媒介昆虫的血淋巴中循环。血淋巴中病毒粒子的稳定性在这一过程中至关重要。酚氧化酶原（PPO）是昆虫血淋巴中主要的天然免疫途径之一。植物病毒如何应对其媒介昆虫中的PPO免疫反应仍不清楚。在这里，我们报告的PPO影响水稻条纹病毒（RSV），一个臭名昭著的水稻病毒，在一个载体昆虫，小褐飞虱的血淋巴的稳定性。RSV使用病毒非结构蛋白抑制PPO活化。一旦PO活性水平升高，RSV就被黑化并从血淋巴中消除。我们的工作提供了宝贵的线索，为发展新的战略控制媒介传播的植物病毒。摘要大多数植物病毒需要媒介昆虫传播。病毒在媒介昆虫血淋巴中的稳定性是持久性植物病毒成功传播的先决条件。然而，知识是否酚氧化酶（PPO）的蛋白水解激活影响持久性植物病毒的稳定性仍然难以捉摸。本文研究了水稻条纹病毒（RSV）与褐飞虱PPO级联反应的相互作用。酚氧化酶（PO）活性被RSV抑制约60%。当PPO级联被激活时，我们发现RSV颗粒周围有明显的黑化，并严重损害了血淋巴中的病毒稳定性。PO活性的病毒抑制来自于通过病毒非结构蛋白NS3的结合阻碍PPO的蛋白水解裂解。这些结果表明RSV减弱PPO应答以确保病毒在媒介昆虫血淋巴中的稳定性。我们的研究为控制媒介传播病毒的传播提供了启发性线索。重要性大比例的媒介植物病毒在进入唾液腺传播给植物之前，先在媒介昆虫的血淋巴中循环。血淋巴中病毒粒子的稳定性在这一过程中至关重要。酚氧化酶原（PPO）是昆虫血淋巴中主要的天然免疫途径之一。植物病毒如何应对其媒介昆虫中的PPO免疫反应仍不清楚。在这里，我们报告的PPO影响水稻条纹病毒（RSV），一个臭名昭著的水稻病毒，在一个载体昆虫，小褐飞虱的血淋巴的稳定性。RSV使用病毒非结构蛋白抑制PPO活化。一旦PO活性水平升高，RSV就被黑化并从血淋巴中消除。我们的工作提供了宝贵的线索，为发展新的战略控制媒介传播的植物病毒。
Large ratios of vector-borne plant viruses circulate in the hemolymph of their vector insects before entering the salivary glands to be transmitted to plants. The stability of virions in the hemolymph is vital in this process. Activation of the proteolytic prophenoloxidase (PPO) to produce active phenoloxidase (PO) is one of the major innate immune pathways in insect hemolymph. How a plant virus copes with the PPO immune reaction in its vector insect remains unclear. Here, we report that the PPO affects the stability of rice stripe virus (RSV), a notorious rice virus, in the hemolymph of a vector insect, the small brown planthopper. RSV suppresses PPO activation using viral nonstructural protein. Once the level of PO activity is elevated, RSV is melanized and eliminated from the hemolymph. Our work gives valuable clues for developing novel strategies for controlling the transmission of vector-borne plant viruses. ABSTRACT Most plant viruses require vector insects for transmission. Viral stability in the hemolymph of vector insects is a prerequisite for successful transmission of persistent plant viruses. However, knowledge of whether the proteolytic activation of prophenoloxidase (PPO) affects the stability of persistent plant viruses remains elusive. Here, we explored the interplay between rice stripe virus (RSV) and the PPO cascade of the vector small brown planthopper. Phenoloxidase (PO) activity was suppressed by RSV by approximately 60%. When the PPO cascade was activated, we found distinct melanization around RSV particles and serious damage to viral stability in the hemolymph. Viral suppression of PO activity was derived from obstruction of proteolytic cleavage of PPOs by binding of the viral nonstructural protein NS3. These results indicate that RSV attenuates the PPO response to ensure viral stability in the hemolymph of vector insects. Our research provides enlightening cues for controlling the transmission of vector-borne viruses. IMPORTANCE Large ratios of vector-borne plant viruses circulate in the hemolymph of their vector insects before entering the salivary glands to be transmitted to plants. The stability of virions in the hemolymph is vital in this process. Activation of the proteolytic prophenoloxidase (PPO) to produce active phenoloxidase (PO) is one of the major innate immune pathways in insect hemolymph. How a plant virus copes with the PPO immune reaction in its vector insect remains unclear. Here, we report that the PPO affects the stability of rice stripe virus (RSV), a notorious rice virus, in the hemolymph of a vector insect, the small brown planthopper. RSV suppresses PPO activation using viral nonstructural protein. Once the level of PO activity is elevated, RSV is melanized and eliminated from the hemolymph. Our work gives valuable clues for developing novel strategies for controlling the transmission of vector-borne plant viruses.