桿狀病毒表現醣類結合蛋白提升殺蟲活性之研究

Enhancing the insecticidal potential of baculovirus by overexpressing the mammalian β-galactosyl binding protein galectin-1

林家揚(Chia-Yang Lin)

指導教授 ： 黃榮南

共同指導教授 ： 吳岳隆(Yueh-Lung Wu)

國立臺灣大學/生物資源暨農學院/昆蟲學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202201876

摘要

在傳統農業模式下，化學農藥導致過多的環境問題，取而代之興起生物性農藥(Bio-pesticide)，生物性農藥不僅具有相當高的專一性，也不會有環境汙染的問題，基於環境和生態保護的理念，生物性農藥一直是農業上的發展重點。在生物性農藥中，病毒為其中一個不可或缺的重要角色，害蟲在病毒感染後會出現生長異常、食慾不振等病徵，並且病毒會在寄主害蟲死亡之後進一步的擴散出去，繼續感染其它寄主，達到永續、長期控制害蟲族群的目的。現行用於蟲害防治上，最普遍的節肢動物病毒為加州苜蓿夜蛾核多角體病毒Autographa californica multiple nucleopolyhedrovirus (AcMNPV)，具有感染多種鱗翅目害蟲的能力，雖此核多角體病毒在生物防治上具有相當程度的潛力，但在實際田間應用卻有效率過低的瓶頸，加上田間的環境因素和作物種類不同的影響，有效防治需要的時間可能會更長，因此很多關於核多角體病毒在防治上的研究都試著縮短其作用時間。為了增強該病毒的防治應用潛力，我們利用桿狀病毒的表現系統 (Baculovirus expression vector system)來表現Galectin-1蛋白質。Galectin-1是一種 β-半乳糖苷的結合蛋白(beta-galactoside-binding protein)，可以結合鱗翅目害蟲中腸內的圍食膜，導致圍食膜上出現孔洞而瓦解，出現停止進食且最終致死的現象。我們的試驗結果顯示帶有galectin-1基因重組的核多角體病毒對多種鱗翅類害蟲的防治成效顯著的提升，基因改造的重組病毒能夠在較短的時間內將寄主殺死，而病毒感染後未立即死亡的寄主，其取食能力也大幅下降，達到降低經濟危害之目的。試驗結果也顯示 Galectin-1主要透過抑制寄主免疫系統而提升桿狀病毒之致病能力，寄主細胞感染重組病毒後，其免疫相關基因的表現量有顯著的下降，此一結果證實Galectin-1重組的桿狀病毒具有抑制昆蟲免疫系統的能力，使得寄主變得更加虛弱，也更容易被其他病原菌二次侵入，顯示Galectin-1能夠有效地增強桿狀病毒之防治效率。

關鍵字

桿狀病毒 ； 蛋白質表現 ； Galectin-1 ； 生物防治 ； 圍食膜 ； 免疫系統

並列摘要

Developing bio-pesticides is an important area of research in agriculture for which viruses are an essential tool. Infection by entomological pathogenic viruses kills agricultural pests, and viral progenies are disseminated to infect more pests, eventually achieving long-term pest control in the field. Of the current virus-based pest control models, Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is the most studied bio-pesticide. AcMNPV belongs to the family Baculoviridae and can infect many lepidopterans. Although AcMNPV has been previously demonstrated as a potential pest-control agent, its long infection cycle has made field application challenging. To overcome this hurdle, we generated a Galectin-1 recombinant baculovirus. Galectin-1 is a mammalian -galactoside-binding protein that could bind to the peritrophic matrix in the midgut of pest lepidopterans and induces perforation of the membrane. Hosts infected with this recombinant virus exhibited reduced appetite and died sooner in both laboratory and small-scale field studies, suggesting that the overexpression of Galectin-1 can more efficiently eliminate pest hosts. Moreover, the immune system of hosts infected with recombinant baculovirus carrying the galectin-1 gene was significantly suppressed, making hosts more vulnerable to secondary infection. To our knowledge, this is the first study explored the effect of Galectin-1 on insect immune systems and demonstrated that the potential of baculovirus for pest control can be improved by overexpressing mammalian Galectin-1.

並列關鍵字

baculovirus ； Galectin-1 ； β-galactosyl binding protein ； bio-control ； immune system

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