| Summary: | 碩士 === 國立成功大學 === 生物科技研究所 === 89 === Baculoviruses mainly infect insects in nature. Because of the relatively slow speed of killing of natural baculoviruses, in comparison with the synthetic chemical insecticides, has restricted their wide spread use in agriculture. The recent development of faster acting genetically modified baculoviruses has provided the opportunity to improve this imperfection. Recombinant baculovirus represents a valuable tool that has the great potential for effective integration into the pest-management system. Recombinant baculoviruses with the insertion of essential host physical regulatory genes or toxin genes into the viral genomes have been reported in recent years, such as juvenile hormone gene, north algerian scorpion neurotoxin, and itch mite’s paralytic neurotoxin.
In this thesis four new candidate genes were chosen as the inserted genes including alkaline lipase (alp), dnase (kdn), and two chitinase (schiA and schiA/BD) genes. In previous experiments, these proteins have been proved to help wild-type baculovirus, Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) to infect larvae. We have constructed four recombinant baculoviruses harboring alp, kdn, schiA and schiA/BD, respectively to compare expression of this baculoviruses. Bioassays of the cytotoxicity on insect cells and larva-killing effects of wild-type AcMNPV and the recombinant viruses were compared. Results showed that recombinant virus vAckdn with DNase has higher virulence and higher speed of killing effects than those of AcMNPV. While recombinant viruses containing alkaline lipase and chitinase did not have significant higher toxicity in SF9 cell than the AcMNPV. The toxicity to larvae, recombinant baculovirus vAcalp with alkaline lipase has a moderate higher efficiency of killing in Plutella xyllostella than the AcMNPV. While these results, it is possible that genetically modified baculoviruses can be used as highly efficient biopesticides in agriculture.
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