探討登革病毒在埃及斑蚊體內成熟之分子調控機制

蚊子是許多疾病的傳播媒介，例如：瘧疾、登革熱、屈躬病、西尼羅熱、黃熱病以及茲卡病毒等。當中，登革熱為現今非常重要的議題，根據世界衛生組織統計顯示，全世界每年大約有3.9億的案例，其中約有9000萬的人口具有臨床症狀，而在台灣2014至2015年之間，即有超過5萬件的感染案例。由於目前仍無有效的藥物及疫苗上市，因此，如何預防病媒蚊的叮咬以及控制病媒蚊的數量，為當前防治蚊媒傳染疾病最重要的研究課題。根據先前研究文獻指出，人體中的一個蛋白質轉化酶 (proprotein convertases, Furin)對於登革病毒成熟的過程中扮演非常重要的角色，經序列比對後，我們發現埃及斑蚊的Vitellogenin convertase (VgC)與Furin具有高度的同源性，而VgC於蚊子吸血後大量表現並參與卵巢發育。因此，本研究以埃及斑蚊為研究模式，探討VgC對於登革病毒成熟的影響。首先，分別給予蚊子正常血液與含有病毒的血液，結果顯示VgC的表現量皆會上升，因此我們推測登革病毒本身並不會影響VgC的表現，而是可能直接利用蚊子吸血後表現的VgC來幫助病毒的成熟。此外，免疫螢光染色法的分析結果顯示，VgC與登革病毒之位置非常接近或是重疊，表示登革病毒有機會與VgC接觸。接著，我們利用Furin inhibitor抑制VgC之活性，發現經Furin inhibitor處理的埃及斑蚊，Vg蛋白質表現量有顯著的下降，由此可確認Furin inhibitor的效用，再者，我們更進一步探討抑制VgC之後，對於登革病毒成熟過程之影響，結果顯示注射Furin inhibitor的組別，其登革病毒的precursor membrane (prM)蛋白質表現量有明顯的上升，表示不成熟的登革病毒顆粒比例相對增加。本研究證實VgC對於登革病毒在成熟過程中所扮演的重要角色，本結果將對於未來在病媒傳播病毒之研究上有重要的幫助。

關鍵字

埃及斑蚊；登革病毒； Furin ； Vg convertase (VgC) ； prM

並列摘要

Mosquitoes are one of the fatal animals in the world and they act as vectors to carry and spread disease to humans, including malaria, dengue fever, West Nile fever, chikungunya and Zika. Among these diseases, dengue fever is an emerging threat in the world. In Taiwan, over 50 thousand cases have been reported in 2014 and 2015. However, there are no effective medication and vaccine for dengue fever available. Thus, developing strategies to fight against mosquito-borne diseases is urgently needed. Previous studies indicated that human Furin, a proprotein convertases, plays an important role in dengue virus (DENV) maturation. We identified a Vitellogenin convertase (VgC) in the mosquito Aedes aegypti to be highly homologous to Furin. VgC has been described to be involved in the production of vitellogenin (Vg) during mosquito vitellogenesis. The aim of this study is to investigate the effect of VgC on DENV maturation. We showed that the VgC transcript was highly expressed after a normal and an infectious blood meal, suggesting that DENV may make use of blood meal-induced VgC for replication. In addition, VgC was found to co-localize with DENV after infection, suggesting that DENV had opportunity to use VgC. Next, we used furin inhibitor to study the effect of VgC in viral replication. To confirm the efficiency of furin inhibitor, we examine the expression of vitellogenin post furin inhibitor treatment. Furthermore, the expression of precursor membrane (prM) protein of DENV was increased after furin inhibitor treatment, indicating that VgC was responsible for DENV maturation. Our results provide new insights into the understanding of DENV and vector interaction which may help to devise a new strategy to eradicate DENV program.

並列關鍵字

Aedes aegypti ； Dengue virus ； Furin ； Vg convertase (VgC) ； prM

參考文獻

Anders, R.F., Adda, C.G., Foley, M., and Norton, R.S. (2010). Recombinant protein vaccines against the asexual blood stages of Plasmodium falciparum. Hum Vaccin 6, 39-53.

Bale, J.F., Jr. (2012). Emerging viral infections. Semin Pediatr Neurol 19, 152-157.

Center for Disease Control and Prevention. (2013). Parasites-Lymphatic filariasis.

Diseases Related to Travel -Yellow fever

Chen, J.S., and Raikhel, A.S. (1996). Subunit cleavage of mosquito pro-vitellogenin by a subtilisin-like convertase. Proc Natl Acad Sci U S A 93, 6186-6190.

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探討登革病毒在埃及斑蚊體內成熟之分子調控機制

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