探討高溫(32℃)抑制白點症病毒於白蝦之複製分子機制

Abstract

中文摘要 水溫升高至 32℃ 時蝦類因白點症病毒 (White spot syndrome virus) 感染的死亡率可大幅降低，但其機制尚未完全明瞭，惟推論可能與高溫下抑制白點症病毒的關鍵調控因子有關。按本實驗室先前的研究指出，草蝦於高溫感染白點症病毒後，醛脫氫酶（NAD-dependent aldehyde dehydrogenase；ALDH）與蛋白酶體第四 α 亞基（Proteasome alpha 4 subunit）的蛋白質表現量會明顯上升。另外，目前的研究亦發現，蝦內熱休克蛋白 70 (Heat shock protein 70；HSP70) 的 mRNA 在高溫病毒感染後其表現量亦會增高，為了探討上述蛋白質是否為高溫抑制白點症病毒的關鍵調控因子，本實驗利用RNA靜默化技術 (RNA interference, RNAi)，使上述特定基因的轉錄表現量下降，並於注射雙股 RNA 48 小時後，注射感染白點症病毒。檢測病毒量之結果發現：注射 aldh 及 hsp70 雙股 RNA 的高水溫 (32℃) 感染組，其病毒量在感染 48 小時後相較於控制組有明顯上升；注射proteasome雙股RNA之高水溫感染組，其病毒量相對於控制組則無明顯變化。反轉錄聚合酶鏈鎖反應 (RT-PCR) 的分析結果也確認實驗組基因在高溫狀況下確實可被靜默化，因此推測 ALDH 與 HSP 70 可能為宿主於高溫時抑制白點病毒複製之關鍵因子，但其詳細機制仍待深入探討。

Abstract Water temperature is one of the most important factors of environment. High temperature (32-33℃) has been proven to reduce the mortality in WSSV infected shrimps, but the mechanism still remains unclear. In previous researches, two-dimensional gel electrophoresis analysis revealed two proteins, NAD-dependent aldehyde dehydrogenases (ALDH) and proteasome alpha 4 subunit that were markedly up-regulated after WSSV infected shrimps at 32℃. Moreover, as referring to heat treatments, it has to be mentioned the heat shock protein family. Heat shock protein family has been considered as one of the most important indicators for heat shock treatments. We then used gene-specific (aldh, proteasome, and heat shock protein 70) dsRNA to silence these genes and found that the high temperature-induced suppression of WSSV was prevented when aldh and hsp70 were silenced. Our results therefore suggest that HSP70 and ALDH might be critical for the suppression of WSSV replication at 32℃.