Inactivation of the ecdysteroid UDP-glucosyltransferase (egt) gene of Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) improves its virulence towards its insect host |
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Authors: | Francisco J. R. Pinedo, Fl vio Moscardi, Teresa Luque, Julie A. Olszewski,Bergmann M. Ribeiro |
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Affiliation: | a Laboratório de Microscopia Eletrônica e Virologia, Departamento de Biologia Celular, Universidade de Brasília, CEP 70910-900, Brasília, DF, Brazil;b Embrapa-Soja, C.P. 231, CEP 86001-970, Londrina, Paraná, Brazil;c Department of Biological Sciences, Imperial College of Science, Technology and Medicine, London SW7 2AZ, UK |
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Abstract: | Some baculovirus have been genetically modified for the inactivation of their ecdysteroid glucosyltransferase (egt) gene, and these viruses were shown to kill infected larvae more rapidly when compared to wild-type virus infections. We have previously identified, cloned, and sequenced the egt gene of Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV). Here we present data regarding the construction of an egt minus (egt−) AgMNPV and its virulence towards its insect host. We have inserted an hsp70-lacZ (3.7 kb) gene cassette into the egt gene open reading frame (ORF) and purified a recombinant AgMNPV (vAgEGTΔ-lacZ). Bioassays with third-instar A. gemmatalis larvae showed that viral occlusion body (OB) production were consistently lower from infections with vAgEGTΔ-lacZ compared to the wild-type virus. A mean of 20.4×108 OBs/g/larva and 40.7×108 OBs/g/larva was produced from vAgEGTΔ-lacZ and AgMNPV infections, respectively. The mean lethal concentration which killed 50% of insects in a treatment group (LC50) for the 10th day after virus treatment (DAT) was 3.9-fold higher for the wild-type virus compared to vAgEGTΔ-lacZ. The recombinant virus killed A. gemmatalis larvae significantly faster (ca. 1–2.8 days), than the wild-type AgMNPV. Therefore, the vAgEGTΔ-lacZ was more efficacious for the control of A. gemmatalis larvae (in bioassays) compared to wild-type AgMNPV. |
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Keywords: | Baculovirus Anticarsia gemmatalis Velvetbean caterpillar Genetic engineering Biological control Ecdysteroid glucosyltransferase |
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