• International Journal of Industrial Entomology and Biomaterials
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• 제1권2호
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• pp.177-181
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• 2000

Spilarctia obliqua(Wlk.) is a serious pest of mulberry which is naturally affected by its nucleopolyhedrosis virus (SoNPV) in field conditions. The polyhedral occlusion bodies (POB's) were hexahedron under scanning and transmission electron microscope and measured 0.42${\mu}{\textrm}{m}$ to 0.67 ${\mu}{\textrm}{m}$ in diameter. The symptoms of NPV infected S. obliqua larvae resembled with that of other NPVs' infected lepidopterous larvae. The pathogenicity and potentiality of this virus against S. obliqua was tested in the laboratory conditions and the results showed 100% mortality in larvae inoculated with SoNPV at 6.23${\times}10^5$ POBs/ml. Therefore, SoNPV appears to have a high potential as a microbial biocontrol agent against S. obliqua larvae.

• International Journal of Industrial Entomology and Biomaterials
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• 제28권1호
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• pp.10-18
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• 2014

Baculoviruses base vectors come to be regarded as methods for in vivo gene delivery and transient expression to the silkworm. In the case of silkworm, B. mori, two types of baculoviruses, AcNPV (Autographa californica nuclear polyhedrosis virus) and BmNPV (Bombyx mori nuclear polyhedrosis virus), are potentially applicable as vectors. Recently, AcNPV showed promising results with some silkworm strains despite different host-specificities. We searched for a highly-permissive silkworm strain in the B. mori stocks of Kyungpook National University that could produce high levels of recombinant protein. Seventy strains were screened using the recombinant AcNPV/BmA3-Luc virus. Based on the measured luciferase activity, the strains could be divided into three groups, high-, middle-, and low-permissive strains, according to their relative recombinant protein expression levels. At 48 hours post-injection, the luciferase activity in the high-permissive strains was 500-fold greater than that of the low-permissive strains. At 72 hours post-injection, a significant elevation in luciferase activity was observed in the hemocytes of all strains. Then, based on the above results, the High Permissive Strain (HPS) S10 and the Low Permissive Strain (LPS) S39 were pick up and was carried out Dot blotting, RT-PCR and Real time PCR.

• 한국응용곤충학회지
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• 제59권4호
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• pp.451-454
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• 2020

양잠은 경북 상주지역의 주요 곤충 산업 가운데 하나이다. 본 연구는 이 지역에서 2020년도에 발생한 바이러스병을 보고한다. 약 20% 이상의 누에(Bombyx mori) 유충이 설사 및 조직용해를 보이면서 대부분 4-5령충 시기에 치사하였다. 병든 개체들에 대해 누에핵다각체바이러스(B. mori nucleopolyhedrosis virus: BmNPV)에 특이적 PCR 진단 기법을 적용한 결과 양성반응을 나타냈다. 병든 개체로부터 조직 추출액을 엽침지법으로 건전한 개체에 처리한 결과 동일한 병징을 확인하였다. 다시 이 바이러스 추출물을 Sf9 세포주에 처리한 결과 세포질에 다수의 바이러스 다각체를 관찰할 수 있었다. 이러한 결과는 상주지역 양잠농가에 발생한 누에 유충 치사는 BmNPV에 의한 바이러스병에 기인된 것으로 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제31권4호
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• pp.529-539
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• 2021

The beet armyworm, Spodoptera exigua, is a serious insect pest infesting various vegetable crops. Two infectious insect viruses, baculovirus and iflavirus, are known to induce epizootics in S. exigua populations. Indeed, some laboratory colonies have appeared to be covertly infected by these viruses. Diagnostic PCR tests detected two different viruses: Spodoptera exigua multiple nucleopolyhedrosis virus (SeMNPV) and iflaviruses (SeIfV1 and SeIfV2). Viral extract from dead larvae of S. exigua could infect Sf9 cells and produce occlusion bodies (OBs). Feeding OBs to asymptomatic larvae of S. exigua caused significant viral disease. Interestingly, both SeIfV1 and SeIfV2 increased their titers at late larval stages. Sterilization of laid eggs with 1% sodium hypochloride significantly reduced SeMNPV titers and increased larval survival rate. Double-stranded RNA (dsRNA) specific to SeIfV1 or SeIfV2 significantly reduced viral titers and increased larval survival rate. To continuously feed dsRNA, a recombinant Escherichia coli HT115 expressing SeIfV1-dsRNA was constructed with an L4440 expression vector. Adding this recombinant E. coli to the artificial diet significantly reduced the SeIfV1 titer and increased larval survival. These results indicate that laboratory colony collapse of S. exigua is induced by multiple viral infections. In addition, either suppression of SeMNPV or SeIfV infection significantly increased larval survival, suggesting a cooperative pathogenicity between baculovirus and iflavirus against S. exigua.