Virus‐Derived Genes for Insect‐Resistant Transgenic Plants (original) (raw)
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Baculoviruses: Emerging Frontiers for Viral Biocontrol of Insect Pests of Agricultural Importance
Accumulated evidences gathered over recent decades demonstrated that Baculoviruses (Occlusion body forming nucleopolyhedroviruses and the host specific granuloviruses) have proven Biocontrol activities on insect and pests of agricultural importance while being non-pathogenic to humans. These studies have laid the foundations for the launch of several trials phases using Baculoviruses on specific insect pests for their efficacy as viral Biocontrol agents. After a brief overview of the biology of Baculoviruses, this review focuses on the studies which unraveled the Biocontrol properties of these agents and supported their use as biopesticides of insect pests resistant to chemical pesticides. Furthermore, this review emphasizes the development of more complex Baculovirus treatment strategies aimed at enhancing formation of occlusion bodies, accelerated virus replication of infective budded forms in insect hosts and improvement of direct lethal effects in several insect developmental forms as necessary tools for increased efficacy in viral Biocontrol of insect pests of agricultural importance. However, the review also addressed the key challenges that
Applied Entomology and Zoology, 2000
A baculovirus virulence-associated protein, enhancin, was engineered for production in a bacuiovirus-insect cell expression system and used for transformation of tobacco plants. A recombinant Autogmpha calijbrnica nucleopolyhedrovirus (AcNPV) with the enhancin gene from 7)'ichoplusia ni granulovirus, AcEnh26, was propagated in Sf9 cells. The infected cultured cells combined with either AcNPV occlusion bodies (OBs) or Elpodoptera exigua NPV (SeNPV) OBs were fed to 3rd stadium Iarvae of S. exigua. Feeding larvae with AcEnh26-infected cells resulted in a 21-fold and 10-fold enhancement of infection by AcNPV and SeNPV, respectively, compared to controls. When a similar feeding assay was performed with engineered tobacco plants, a 10-fold enhancement of AcNPV infection was observed, but a marked enhancement of SeNPV infection was not observed. Thus, the engineering and expression of the baculovirus enhancin gene in homologous and heterologous organisms allowed us to analyze its effects on NPV infection of larvae which demonstrated its viral enhancement function.
Baculovirus vector-mediated expression of heterologous genes in insect cells
J Biosciences, 1994
The baculovirus expression system employing Autagrapha californica nuclear polyhidrosis virus and Spodoptera frugiperda insect cells in culture has proved very popular for high level expression of heterologous genes: In this system, transcription of the foreign gene is usually driven by the hyperactive and temporally regulated polyhedrin gene promoter. Replacement of the polyhedrin gene, which encodes a 29-kDa occlusion protein (non-essential for viral replication), with a gene of interest leads to an occlusion negative phenotype which serves as a visual marker to select for recombinant viruses. Simultaneous expression of multiple genes can also be achieved. The heterologous proteins synthesized in this system are antigenically, immunologically and functionally identical in most respects to their native counterparts. This mini-review will aim at summarizing the potentials and utility of the baculovirus expression vector system and will address some important questions relating to the biology of this system.
Baculovirus studies in new, indigenous lepidopteran cell lines
Indian journal of experimental biology, 2002
Eight lepidopteran cell lines were established recently and their susceptibility to different insect viruses was studied. Two Spodoptera litura cell lines from the larval and pupal ovaries, were found highly susceptible to S. litura nuclear polyhedrosis virus (SLNPV, 5-6 x 10(6) NPV/ml). The Helicoverpa armigera cell line from the embryonic tissue was highly susceptible to H. armigera NPV (HaNPV, 6.3 x 10(6) NPV/ml). These in vitro grown SLNPV and HaNPV caused 100% mortality to respective 2nd instar larvae. The susceptibility of the cryo-preserved cell lines to respective baculoviruses (SLNPV/HaNPV) was studied and no significant difference in their susceptibility status was observed. The cultures could grow as suspension culture on shakers and may find application for in vitro production of wild type/recombinant baculoviruses as bio-insecticides. S. litura and Bombyx mori cell lines from larval ovaries, were highly susceptible to Autographa californica NPV (5.5 x 10(6) NPV/ml) and ...
Identification of pif-2, a third conserved baculovirus gene required for per os infection of insects
Journal of General Virology, 2003
Infection of cultured insect cells with Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV) resulted in the generation of mutants with major genomic deletions. Some of the mutants lacked the ability to infect S. exigua larvae per os. The gene(s) responsible for this phenotype in SeMNPV was mapped within a contiguous sequence encoding ORFs 29-35. In this paper we have shown that SeMNPV ORFs 15-35 (including genes encoding cathepsin, chitinase, GP37, PTPT-2, EGT, PKIP-1 and ARIF-1) are not essential for virus replication in cell culture or by in vivo intrahaemocoelic injection. By site-specific deletion mutagenesis of a full-length infectious clone of SeMNPV (bacmid) using ET recombination in E. coli, a series of SeMNPV bacmid mutants with increasing deletions in ORFs 15-35 was generated. Analyses of these mutants indicated that a deletion of SeMNPV ORF35 (Se35) resulted in loss of oral infectivity of polyhedral occlusion bodies. Reinsertion of ORF35 in SeMNPV bacmids lacking Se35 rescued oral infectivity. We propose the name pif-2 for Se35 and its baculovirus homologues (e.g. Autographa californica MNPV ORF22), by analogy to a different gene recently characterized in Spodoptera littoralis NPV, which was designated per os infectivity factor (pif). Similar to the p74 gene, which encodes an essential structural protein of the occlusion-derived virus envelope, pif and pif-2 belong to a group of 30 genes that are conserved among the Baculoviridae.
Baculovirus and Insect Cell Expression Protocols
Methods in molecular biology, 2016
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