|Abstract: ||臺灣為登革熱發生的高風險地區，然而我國目前沒有核准上市的疫苗或藥物，因此為重要的防疫問題。文獻指出紅藻水萃物具有抗氧化、抗發炎及免疫激活等效果。因此本研究旨在探討紅藻門的海木耳 (Sarcodia montagneana) 其水萃物對感染第二型登革病毒 (Dengue virus type 2, DENV2) 的保護效果。以熱水萃取法進行萃取，海木耳水萃物的產率為 60%，且經凝膠滲透層析儀 (Gel permeation chromatography, GPC) 分析，海木耳水萃物主要以 708 kDa 多醣及180 Da 單醣組成。細胞實驗利用 BHK-21 和DENV2 進行病毒斑抑制試驗 (Plaque reduction assay) 及定量即時聚合酶鏈鎖反應 (Quantitative real time polymerase chain reaction, q-PCR) 評估海木耳水萃物 (Sarcodia montagneana water extract, SMw) 是否能降低病毒量，體外實驗結果顯示，500 μg/mL 海木耳水萃物於預防 (Pre-treatment)、共培養 (Co-treatment) 及治療 (Post-treatment) 條件下分別有 93%、99% 及 55% 的病毒斑抑制率。感染組細胞內DENV2 NS5 表現量與時間成正比，而以預防、共培養及治療條件給予 SMw 可顯著降低細胞內DENV2 NS5 表現量，推測海木耳水萃物是藉由吸附宿主表面受器或病毒顆粒達到降低第二型登革病毒感染的效果。動物實驗部分，將 500 μg/mL 海木耳水萃物和 50 PFU 的 DENV2 共培養後，顱內感染十日齡 C3H/HeN 乳鼠可提升 50 % 的乳鼠存活率。另一方面，以預防條件於顱內感染前五日開始餵食海木耳水萃物，結果顯示，餵食5 mg 劑量的乳鼠相較於感染組可延長存活天數，臟器中病毒量也有顯著減少且具有減緩肝損傷的效果，由實驗結果推論，海木耳水萃物具有保護宿主且降低 DENV2 感染的效果。|
Taiwan is a high-risk area where dengue fever occurs. However, there are no approved vaccines or drugs in Taiwan, so it is an important epidemic prevention problem. The literature indicate that the red algae water extract had anti-oxidation, anti-inflammatory and immune activation effects. Therefore, this study was aim to investigate the protective effect of the water extract of Sarcodia montagneana of Rhodophyta on the dengue virus type Ⅱ (DENV2) infection. Extracted by hot water extraction, the yield of Sarcodia montagneana water (SMw) extract is 60%. Use gel permeation chromatography (GPC) to analyze SMw, it was mainly comprise 708 kDa polysaccharide and 180 Da monosaccharide. In vitro, used baby hamster kidney-21 (BHK-21) cell and DENV2 for plaque inhibition assay and quantitative real-time polymerase chain reaction (q-PCR) to assess whether the SMw could reduce the virus burden. The results showed that the SMw (500 μg/mL) has 93%, 99%, and 55% plaque reduction rate in pre-treatment, co-treatment, and post-treatment condition, respectively. The expression of DENV2 NS5 gene in the virus group increased with time, while SMw significantly decreased the intracellular DENV2 NS5 gene expression in pre-treatment, co-treatment, and post-treatment condition. It was supposed that SMw could decrease the infection of DENV2 by absorbing the host surface receptor or virus particles. In vivo, intracranial infection of 10-day-old C3H/HeN suckling mice with mixture of 500 μg/mL SMw and DENV2 could increase the survival rate of 50%. Further, we administered 5 mg SMw on the 5th day before the intracranial infection, and the results showed that fed SMw could extend survival days. The virus load in organs was also significantly reduced and had the effect of improve liver injury. Those results showed that SMw had the effect of protect host and decrease DENV2 infection.