神經壞死病毒(NNV)的爆發一直是導致石斑魚高死亡率的主要問題，且在NNV誘導的逆境下，體內穩態(homeostasis)的平衡會被破壞並使蛋白質失去功能。而為了維持宿主體內穩態，在真核生物中，有兩個主要蛋白質管理系統包括熱休克反應及自噬作用，但在病毒感染過程中石斑魚如何介導兩種穩態反應仍尚不清楚。因此在本研究中，分別利用HSF1和LC3作為各自的標記來了解這兩者之間的交互關係。在獲得及失去功能的實驗中，發現熱休克反應會控制自噬作用反應，但當自噬作用足夠時則會對熱休克反應形成負向回饋，顯示熱休克反應和自噬作用能夠彼此協調。而在病毒逆境下，熱休克(36°C)或大量表現HSF1b具有較高的病毒RNA2表現會促進NNV複製；但在雷帕黴素處理或大量表現LC3則會減少病毒量，這顯示兩者在對抗NNV感染時的作用則相反。另一方面，熱休克反應和自噬作用間的交互作用則會拮抗NNV CP的表達，顯示兩種反應間的平衡會決定感染的嚴重程度。因此綜合上述結果，熱休克反應的抑制結合自噬作用的活化可能在對抗NNV感染上可以提供更好的防護效果。而這些發現也幫助我們了解防禦機制間的協調作用，進而提高石斑魚存活率並減少其經濟損失。

The outbreak of nervous necrosis virus (NNV) has been the major problem that causes high mortality in groupers. Under NNV induced stress, the balance of homeostasis is disrupted and proteins become dysfunctional. In order to maintain host homeostasis, there are two main protein quality control in eukaryotes: heat shock response (HSR) and autophagy. However, it still remains unknown how groupers mediate two homeostatic responses during viral infection. In this study, HSF1 and LC3 are used as markers to determine the interaction between both responses. Through gain and loss of function experiments, HSR controlled autophagy but sufficient autophagy was negatively fed back to HSR, showing that HSR and autophagy regulated each other. Under stress of NNV infection, heat shock (36°C) or overexpression of HSF1b promoted NNV replication with higher viral RNA2 expression, but rapamycin treatment or overexpression of LC3 reduced the viral load, indicating that two responses had opposite roles against NNV infection. On the other hand, the interaction between HSR and autophagy counteracted the degree of NNV CP expression, suggesting that the severity of an infection depended on the balance of these two responses. Taken together, HSR inhibition combined with autophagy activation may provide better protection against NNV infection. These findings also help us understand the coordination between the defense mechanisms to improve the grouper survival and reduce the economic loss.

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