Insecticidal activity of a recombinant baculovirus containing an antisense c-myc fragment

Expression, delivery and function of insecticidal proteins expressed by recombinant baculoviruses

Since the development of methods for inserting and expressing genes in baculoviruses, a line of research has focused on developing recombinant baculoviruses that express insecticidal peptides and proteins. These recombinant viruses have been engineered with the goal of improving their pesticidal potential by shortening the time required for infection to kill or incapacitate insect pests and reducing the quantity of crop damage as a consequence. A wide variety of neurotoxic peptides, proteins that regulate insect physiology, degradative enzymes, and other potentially insecticidal proteins have been evaluated for their capacity to reduce the survival time of baculovirus-infected lepidopteran host larvae. Researchers have investigated the factors involved in the efficient expression and delivery of baculovirus-encoded insecticidal peptides and proteins, with much effort dedicated to identifying ideal promoters for driving transcription and signal peptides that mediate secretion of the expressed target protein. Other factors, particularly translational efficiency of transcripts derived from recombinant insecticidal genes and post-translational folding and processing of insecticidal proteins, remain relatively unexplored. The discovery of RNA interference as a gene-specific regulation mechanism offers a new approach for improvement of baculovirus biopesticidal efficacy through genetic modification.

Identification of a single-nucleocapsid baculovirus isolated from Clanis bilineata tsingtauica (Lepidoptera: Sphingidae)

A nucleopolyhedrovirus isolated from infected larvae of Clanis bilineata tsingtauica was characterized. Electron microscopical studies on the ultrastructure of C. bilineata nucleopolyhedrovirus (ClbiSNPV) occlusion bodies (OBs) showed several virions (up to 16) with a single nucleocapsid packaged within a single viral envelope. The diameter of the OBs was 0.77-1.7 mum with a mean of 1.13 +/- 0.19 mum. The complete sequence of the ClbiSNPV polyhedrin (polh) gene contained 741 nucleotides, predicting a protein of 246 amino acids. Phylogenetic analyses using the complete sequence of the polh genes indicated that ClbiSNPV clusters with Group II NPVs. This is the first record of a baculovirus from C. bilineata.

Genetically modified baculoviruses: a historical overview and future outlook

The concept of using genetic engineering to improve the natural insecticidal activity of baculoviruses emerged during the 1980s. Both academic and industrial laboratories have since invested a great deal of effort to generate genetically modified (GM) or recombinant baculoviruses with dramatically improved speeds of kill. Optimal production methodologies and formulations have also been developed, and the safety and ecology of the recombinant baculoviruses have been thoroughly investigated. Unfortunately, the initial excitement that was generated by these technologies was tempered when industry made a critical decision to not complete the registration process of GM baculoviruses for pest insect control. In this chapter, we summarize the developments in the field from a historical perspective and provide our opinions as to the current status and future potential of the technology. We will argue that GM baculoviruses are valuable and viable tools for pest insect control both alone and in combination with wild-type viruses. We believe that these highly effective biopesticides still have a bright future in modern agriculture as public awareness and acceptance of GM organisms, including GM baculoviruses, increases.