Anti-melanization mechanism of the white spot syndrome viral protein, WSSV453, via interaction with shrimp proPO-activating enzyme, PmproPPAE2
Anti-melanization mechanism of the white spot syndrome viral protein, WSSV453, via interaction with shrimp proPO-activating enzyme, PmproPPAE2
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DOI：
10.1099/jgv.0.000729
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发表时间：
2017-04-01
影响因子：
3.8
通讯作者：
Tassanakajon, Anchalee
中科院分区：
文献类型：
--
作者：
Sutthangkul, Jantiwan;Amparyup, Piti;Tassanakajon, Anchalee
酚氧化酶原激活系统（prophenoloxidase activating，proPO）激活宿主黑化反应，抑制宿主黑化反应是病原体逃避病原体的重要策略之一。最近，对虾病原体，白色斑点综合征病毒（WSSV），被发现抑制虾斑节对虾的黑化。病毒蛋白WSSV 453以前被证明与PO激活酶2（PmPPAE 2）相互作用，并报道参与抑制WSSV感染后的虾黑化反应。在这里，我们表征了WSSV 453如何抑制黑化。WSSV 453是一种非结构病毒蛋白，首次在WSSV感染后6小时（hpi）在虾血细胞中检测到，并于24 hpi在虾血浆中检测到。我们生产了斑节对虾proPO系统的三种组分的重组蛋白：PmproPPAE 2、PmproPO 1和PmproPO 2。功能分析表明，活性PmPPAE 2处理PmproPO 1和2产生功能PO。WSSV 453与PmproPPAE 2的孵育剂量依赖性地降低了PmPPAE 2对PmPO 1或PmPO 2的活性。相反，WSSV 453对活化的PmPPAE 2没有影响。在感染后第2天，将活性PmPPAE 2添加到WSSV感染的虾血浆中也挽救了PO活性。总之，这些结果表明WSSV的抗黑化活性是由于WSSV 453，其与PmproPPAE 2相互作用并干扰其活化为活性PmPPAE 2。
Inhibition of the host melanization reaction, activated by the prophenoloxidase activating (proPO) system, is one of the crucial evasion strategies of pathogens. Recently, the shrimp pathogen, white spot syndrome virus (WSSV), was found to inhibit melanization in the shrimp Penaeus monodon. The viral protein WSSV453 was previously shown to interact with PO-activating enzyme 2 (PmPPAE2) and reported to be involved in suppressing the shrimp melanization response after WSSV infection. Here, we characterized how WSSV453 inhibits melanization. WSSV453 is a non-structural viral protein, which was first detected in shrimp haemocytes at 6 hours post-infection (hpi) by WSSV and in shrimp plasma at 24 hpi. We produced recombinant proteins for three components of the P. monodon proPO system: PmproPPAE2, PmproPO1 and PmproPO2. Functional assays showed that active PmPPAE2 processed PmproPO1 and 2 to produce functional PO. Incubation of WSSV453 with PmproPPAE2 dose-dependently reduced PmPPAE2 activity toward PmPO1 or PmPO2. In contrast, WSSV453 had no effect on activated PmPPAE2. The addition of active PmPPAE2 to WSSV-infected shrimp plasma at day 2 post-infection also rescued PO activity. Taken together, these results indicate that the anti-melanization activity of WSSV is due to WSSV453, which interacts with PmproPPAE2 and interferes with its activation to active PmPPAE2.